Draft Environmental Impact Report Upper York Creek Ecosystem Restoration Project Napa County, California (State Clearinghouse No. 2006092096)
CEQA Lead Agency City of St. Helena 1480 Main Street St. Helena, CA 95474
Contact: Jonathon Goldman Director of Public Works/City Engineer 707-968-2658
A Joint Project of the City of St. Helena, Napa County, California U.S. Army Corps of Engineers, San Francisco District, South Pacific Division
April 20, 2007 Upper York Creek Ecosystem Restoration Draft EIR
City of St. Helena
Upper York Creek Ecosystem Restoration Draft EIR
TABLE OF CONTENTS Page EXECUTIVE SUMMARY ...... ES-1 1 PROPOSED ACTION ...... 1 1.1 Project Description and Objectives ...... 1 1.2 Project Location ...... 1 1.3 Characteristics of the Project Area ...... 3 1.4 Project Background and History ...... 3 1.5 Environmental Process and Timeline ...... 5 1.5.1 Project Sponsors ...... 5 1.5.2 CEQA Lead Agency ...... 5 1.5.3 CEQA Responsible and Trustee Agencies ...... 6 1.5.4 Public Participation and Timeline ...... 6 1.5.5 Timeline for Project Implementation ...... 7 1.6 Regulatory Background for the Project ...... 7 1.6.1 Ecological Permits ...... 7 1.6.2 Fish and Wildlife Coordination Act ...... 9 1.6.3 National Historic Preservation Act ...... 9 1.6.4 Migratory Bird Treaty Act ...... 10 1.6.5 California Global Warming Solutions Act of 2006 ...... 10 2 ALTERNATIVES CONSIDERED FOR THE PROJECT ...... 11 2.1 All Alternatives Considered ...... 11 2.2 Alternatives Analyzed in DEIR ...... 12 2.2.1 No Project ...... 12 2.2.2 Small Notch ...... 12 2.2.3 Full Dam Removal ...... 14 2.2.4 Fish Ladder ...... 14 2.2.5 Summary of Alternatives ...... 15 2.3 Elements Included in All Action Alternatives ...... 16 2.3.1 Habitat Restoration ...... 16 2.3.2 Stabilization of Spring Mountain Road ...... 17 2.3.3 Species of Concern ...... 17 2.3.4 Dewatering ...... 17 2.3.5 Construction Access ...... 17 2.3.6 Sediment Reuse/Disposal ...... 17 3 ENVIRONMENTAL SETTING AND CONSEQUENCES OF PROJECT ALTERNATIVES ...... 23 3.1 Aesthetics ...... 23 3.1.1 Setting ...... 23 3.1.2 Standards ...... 23 3.1.3 No Project Alternative: Impacts and Mitigation Measures ...... 23 3.1.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 25 3.1.5 Full Dam Removal: Impacts and Mitigation Measures ...... 26 3.1.6 Fish Ladder: Impacts and Mitigation Measures ...... 26 3.1.7 Section References ...... 26
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3.2 Air Quality ...... 27 3.2.1 Setting ...... 27 3.2.2 Standards ...... 30 3.2.3 No Project Alternative: Impacts and Mitigation Measures ...... 31 3.2.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures, ...... 33 3.2.5 Full Dam Removal: Impacts and Mitigation Measures ...... 35 3.2.6 Fish Ladder: Impacts and Mitigation Measures ...... 36 3.2.7 Section References ...... 36 3.3 Biological Resources ...... 38 3.3.1 Setting ...... 38 3.3.2 Standards ...... 77 3.3.3 No Project Alternative: Impacts and Mitigation Measures ...... 78 3.3.4 Preferred Alternative - Small Notch: Impacts and Mitigation Measures ...... 86 3.3.5 Full Dam Removal: Impacts and Mitigation Measures ...... 91 3.3.6 Fish Ladder: Impacts and Mitigation Measures ...... 92 3.3.7 Section References ...... 93 3.4 Cultural Resources ...... 97 3.4.1 Setting ...... 97 3.4.2 Standards ...... 98 3.4.3 No Project Alternative: Impacts and Mitigation Measures ...... 98 3.4.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 98 3.4.5 Full Dam Removal: Impacts and Mitigation Measures ...... 99 3.4.6 Fish Ladder: Impacts and Mitigation Measures ...... 99 3.4.7 Section References ...... 99 3.5 Geology, Soils, Landslides, and Seismic Activity ...... 101 3.5.1 Setting ...... 101 3.5.2 Standards ...... 104 3.5.3 No Project Alternative: Impacts and Mitigation Measures ...... 105 3.5.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 105 3.5.5 Full Dam Removal: Impacts and Mitigation Measures ...... 107 3.5.6 Fish Ladder: Impacts and Mitigation Measures, Success Criteria ...... 107 3.5.7 Section References ...... 107 3.6 Global Climate Change ...... 109 3.6.1 Setting ...... 109 3.6.2 Standards ...... 115 3.6.3 No Project Alternative: Impacts and Mitigation Measures ...... 115 3.6.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 116 3.6.5 Full Dam Removal: Impacts and Mitigation Measures ...... 117 3.6.6 Fish Ladder: Impacts and Mitigation Measures ...... 117 3.6.7 Section References ...... 118
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3.7 Hazardous Materials ...... 121 3.7.1 Setting ...... 121 3.7.2 Standards ...... 124 3.7.3 No Project Alternative: Impacts and Mitigation Measures ...... 124 3.7.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 126 3.7.5 Full Dam Removal: Impacts and Mitigation Measures ...... 128 3.7.6 Fish Ladder: Impacts and Mitigation Measures ...... 128 3.7.7 Section References ...... 128 3.8 Hydrology and Hydraulics ...... 130 3.8.1 Setting ...... 130 3.8.2 Standards ...... 137 3.8.3 No Project Alternative: Impacts and Mitigation Measures ...... 137 3.8.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 139 3.8.5 Full Dam Removal: Impacts and Mitigation Measures ...... 141 3.8.6 Fish Ladder: Impacts and Mitigation Measures ...... 142 3.8.7 Section References ...... 143 3.9 Noise ...... 144 3.9.1 Setting ...... 144 3.9.2 Standards ...... 144 3.9.3 No Project Alternative: Impacts and Mitigation Measures ...... 145 3.9.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 146 3.9.5 Full Dam Removal: Impacts and Mitigation Measures ...... 146 3.9.6 Fish Ladder: Impacts and Mitigation Measures ...... 146 3.9.7 Section References ...... 146 3.10 Transportation and Traffic ...... 148 3.10.1 Setting ...... 148 3.10.2 Standards ...... 149 3.10.3 No Project Alternative: Impacts and Mitigation Measures ...... 149 3.10.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 150 3.10.5 Full Dam Removal: Impacts and Mitigation Measures ...... 152 3.10.6 Fish Ladder: Impacts and Mitigation Measures ...... 152 3.10.7 Section References ...... 152 3.11 Water Quality ...... 153 3.11.1 Setting ...... 153 3.11.2 Standards ...... 157 3.11.3 No Project Alternative: Impacts and Mitigation Measures ...... 158 3.11.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures ...... 161 3.11.5 Full Dam Removal: Impacts and Mitigation Measures ...... 161 3.11.6 Fish Ladder: Impacts and Mitigation Measures ...... 161 3.11.7 Section References ...... 162
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4 IMPACTS ANALYSIS ...... 163 4.1 Significant and Unavoidable Impacts ...... 163 4.1.1 No Project Alternative ...... 163 4.1.2 Action Alternatives ...... 163 4.2 Cumulative Impacts ...... 164 4.2.1 Global Climate Change ...... 166 4.2.2 Traffic ...... 166 4.3 Irreversible Impacts ...... 166 4.4 Growth Inducing Effects ...... 166 4.5 Short-term Impacts vs. Long-term Effects ...... 167 4.6 Beneficial Effects and the Environmentally Superior Alternative ...... 167 5 LIST OF PREPARERS AND REVIEWERS ...... 169 5.1 EIR Consultants ...... 169 6 ACRONYMS AND ABBREVIATIONS ...... 170 7 REFERENCES ...... 173
FIGURES
Figure 1. Project Location Map ...... 2 Figure 2. Conceptual Cross Sections of Action Alternatives ...... 13 Figure 3. Plan View of Small Notch...... 19 Figure 4. Plan View of Full Dam Removal...... 20 Figure 5. Plan View of Fish Ladder...... 21 Figure 6. Upper York Creek Reservoir Existing Vegetation and Habitats ...... 41 Figure 7. Lower York Creek Reservoir Existing Vegetation and Habitats ...... 43 Figure 8. Spring Mountain Vinedyard Existing Vegetation and Habitats ...... 45 Figure 9. Current Global, National, and State Greenhouse Gas Emissions ...... 109 Figure 10. California Sources of Greenhouse Gas Emissions ...... 110 Figure 11. Approximate Locations of Overbank Flows in Lower York Creek...... 135 Figure 12. Characteristics of the Upper Watershed Channels...... 135 Figure 13. The York Creek Channel through the City of St. Helena...... 136 Figure 14. Aggraded Channel in the Beringer Winery Reach...... 136
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TABLES
Table ES1. Comparison of Impacts and Mitigation Measures of Project Alternatives ...... 7 Table 1. Corps and City Project Alternatives ...... 12 Table 2. Comparison of Objectives Met in Relation to Each Alternative...... 15 Table 3. Estimated Materials Placement Quantities for Action Alternatives...... 18 Table 4. Air Quality in the San Francisco Bay Area and Napa County ...... 29 Table 5. Upper St. Helena Dam, Expected Project Emissions ...... 30 Table 6. Plant Species Observed within the Project Area ...... 46 Table 7. Fish and Wildlife Species Observed within the Project Area ...... 52 Table 8. Special-Status Plant Species Considered in Project Evaluation ...... 55 Table 9. California Natural Communities Considered in Project Evaluation ...... 63 Table 10. Special-Status Animal Species Considered in Project Evaluation ...... 64 Table 11. Soil Properties ...... 102 Table 12. Historic, Holocene, and Late Quaternary Faults ...... 103 Table 13. Historic and Current Concentrations of Greenhouse Gases...... 111 Table 14. OSHA Permissible Exposure Levels ...... 124 Table 15. Statistically Derived Rainfall Intensities Used to Estimate Peak Stream Flow for the Given Return-Period Storm Event...... 132 Table 16. York Creek Peak Stream Flows associated with Standard Recurrence Intervals at Several Locations in the Watershed...... 133 Table 17. Level of Service (LOS) Classifications ...... 148 Table 18. Existing Traffic on Hauling Routes and Expected Project Impacts ...... 150 Table 19. Asbestos Test Results from York Creek. 9-27-2006. EPA 100.2 Method ...... 155 Table 20. Asbestos Test Results from York Creek*. 1-24-07. EPA 100.2 Method ...... 156 Table 21. Sulfide Test Results from York Creek. 9-27-2006. EPA 376.2 Method ...... 157 Table 22: Water Quality Objectives from the San Francisco Bay Basin Plan for Surface, Cold Water Habitats ...... 158
APPENDICES
Appendix 1. Initial Study, Upper York Creek Restoration Project Appendix 2. Lower York Creek Reservoir Revegetation and Mitigation Plan Appendix 3. Notice of Preparation of a Draft Environmental Impact Report, Upper York Creek Restoration Project Appendix 4. Wetland Delineation for Lower York Creek Reservoir Appendix 5. Cultural Resources Appendix 6. Traffic Study Memo
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Executive Summary
The proposed action is the Upper York Creek Ecosystem Restoration Project at the Upper York Creek Dam and Reservoir (UYCD), also referred to as the Upper St. Helena Dam. The project sponsors, the City of St. Helena (City) and the U.S. Army Corps of Engineers, San Francisco District, South Pacific Division (Corps), propose to remove or modify the dam and appurtenances, remove accumulated sediment, and restore the local ecology of York Creek. The City is serving as Lead Agency under the California Environmental Quality Act (CEQA) and has prepared this Draft Environmental Impact Report (DEIR). The purpose of the DEIR is to inform public agency decision-makers and the general public of the significant environmental effects of the project, to identify ways to minimize the significant effects, and to describe reasonable alternatives to the project (CCR §15121).
Upper St. Helena Dam is located approximately 1.5 miles upstream of the City of St. Helena on Spring Mountain Road (Figure 1). Constructed in 1900 to expand water capacity for the rapidly growing City of St. Helena and the local wine industry, UYCD was designed with a storage capacity of 10 million gallons. The earthen dam was originally 35 feet high and 140 feet long and was composed of more than 12,000 cubic yards of channel-bed material that, when excavated, formed the upper reservoir. The dam was modified in the 1930s with the installation of a concrete spillway along Spring Mountain Road and a drop-inlet extension to the out-flow culvert. The dam height was raised 15 feet, and the sluice gates were removed. With these alterations, the dam can no longer be operated as a managed water-storage facility, nor is it large enough to provide downstream flood control.
The reservoir traps the annual supply of gravel and fine sediments produced by the watershed above UYCD. Sediment accumulates in the reservoir at a rate of 1,000 to 5,000 cubic yards per year depending on the magnitude of winter storm events. With total sediment storage potential of 28,000 cubic yards of material, the reservoir pool area is filled every 15-20 years. Over 100 years of sediment trapping has altered the geomorphology of York Creek downstream of UYCD and is thought to be a significant contributing factor to the six to eight feet of bed incision that has occurred in the Napa River over the last century (Stillwater Sciences 2002). Regular maintenance of the dam is required, including annual debris removal from the drop-inlet and spillway to maintain storm water passage and periodic removal of accumulated sediment.
Four documented incidents of accidental, catastrophic releases of fine sediment have occurred during maintenance activities at UYCD. These low-flow sediment discharges have resulted in mortality of fish and other aquatic organisms over the entire stretch of York Creek below the dam. York Creek contains the highest quality steelhead spawning and rearing habitat in the central Napa River Basin, and maintenance of this habitat is very important to support overall Napa River steelhead populations (NCRCD 2005). The recurring fish kills, together with the dam being a total barrier to aquatic migration, initiated formal enforcement actions from the California Department of Fish and Game (CDFG) and NOAA Fisheries Service requiring removal of UYCD.
UYCD significantly impacts critical biological resources in the York Creek and Napa River watersheds. The objectives for removing or modifying UYCD are to restore fish passage for steelhead (Oncorhynchus mykiss), reduce potential for future downstream low-flow fine
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sediment releases and their associated fish kills, and allow for the restoration of approximately 3 acres of degraded riparian and aquatic habitat surrounding the dam and reservoir. Maintaining the stability of the adjoining Spring Mountain Road is considered a project constraint that must be addressed adequately to achieve project success (Corps 2006a).
The City first applied to the Corps Regulatory Branch for permission to address the dam in 1993. This application and a revised application in 1994 were determined to be incomplete. In 2000, the City Council resolved that the Upper St. Helena Dam should at least be breached to allow fish passage. The City formed a partnership with the Corps Civil Works Branch in 2001 that initiated planning for implementation of the Upper York Creek Ecosystem Restoration Project. As part of the larger fish-passage restoration project, removal of a City water-diversion structure 0.5 miles downstream of the dam was completed in 2004.
The Corps initially evaluated seven preliminary alternatives in the feasibility study for the Upper York Creek Ecosystem Restoration Project. Three were eliminated early in the analysis as ineffective or inefficient. Both a small and a large notch in the dam were evaluated, but it was determined that geotechnical slope stability constraints outweighed the small gain in floodplain area offered by the large notch alternative. (Corps 2006b)
Based upon the Corps’ recommendations, no project and three action alternatives are evaluated herein. The alternatives analyzed are discussed briefly here and in greater detail in Section 2:
• No Project – The historic Upper St. Helena Dam would not be altered from its current configuration. No ecosystem restoration measures would be implemented. Regular maintenance dredging of the reservoir would be required to offset the continued deposition of materials behind the dam to prevent sediment releases. • Preferred Alternative – Small Notch – A small notch would be cut into the dam to allow for fish passage and habitat connectivity above and below the dam. A 23-foot wide stream channel would be restored. The existing spillway adjacent to Spring Mountain Road would remain intact and be filled with sediment from the project area, and two layers of inclined screw anchors and subdrains would be installed to provide slope stability. • Full Dam Removal – The entire dam, right wall of the spillway (looking downstream), and the drop inlet would be removed. A 23-foot wide restored stream channel with a 30- foot wide floodplain bench would be created through the dam area. Three layers of inclined screw anchors and subdrains would provide slope stability for Spring Mountain Road. • Fish Ladder – This alternative would create a concrete step-pool/weir fish ladder cut into the dam. Fish passage and habitat connectivity would be partially restored. The Fish Ladder Alternative does not allow for natural sediment transport and would require on- going maintenance to prevent it from becoming clogged with sediment and other debris.
A cross sectional rendering and plan views of the three action alternatives are provided in Figures 2-5 in Section 2. For cross-referencing with Corps documents, these alternatives are identified by the Corps as No Project, Alternative 1 (Full Dam Removal), Alternative 2B (Small
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Notch), and Alternative 3 (Fish Ladder). The alternatives are identified by name only in this document; no numbering is used.
Sediment removed from the dam and reservoir will be placed at one or more locations in or near the City of St. Helena, including a private upland vineyard (Spring Mountain Vineyard), Lower York Creek Reservoir, and Clover Flat landfill. Early in the planning process, the City conducted a preliminary investigation to evaluate if material from the restoration project could be useful to address flood control issues at Fulton Lane within the City limits. However, neither the form nor the location of the flood control work has been established, so impacts cannot be assessed at this time. If the City and private landowners reach an agreement on how to address flooding at Fulton Lane, additional environmental review will occur.
The Initial Study (Appendix 1 [PCI 2006]) determined that further analyses of potential impacts to mineral resources, public services, utilities, recreation, land use/planning, and population/ housing were not required. With removal of Fulton Lane as a potential reuse site, no impacts to agricultural resources will occur. In fact, beneficial effects will occur at Spring Mountain Vineyard where materials from the reservoir will be used to amend the currently fallow land.
Full discussion of the following resources, potential impacts from each alternative, and proposed mitigation measures is found in Section 3:
• Aesthetics • Air Quality • Biological Resources • Cultural Resources • Geology, Soils, Landslides, and Seismic Activity • Global Climate Change • Hazardous Materials • Hydrology and Hydraulics • Noise • Transportation and Traffic • Water Quality
Table ES-1 below summarizes impacts of the proposed project’s alternatives as analyzed in the DEIR, identifies the level of significance of each impact before mitigation, recommends feasible and appropriate mitigation measures, and identifies the level of significance after mitigation for each impact. The level of significance is included for each impact based on the following classification system: significant unavoidable impact (SU), potentially significant and unavoidable (PSU), less than significant (LS), and not applicable (N/A). Section 1.6 summarizes compliance with applicable laws and regulations.
The City and the Corps have worked with local, state, and federal agencies and involved the public during the planning process. No significant public controversy regarding the proposed action has emerged to date. The public involvement process and timeline are discussed in Section 1.5.
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Issues to be Resolved for the Action Alternatives The City has identified several issues to be resolved involving implementation of all of the action alternatives, including potentially significant impacts to aesthetics and noise from project activities at the Lower York Creek Reservoir, to historic resources through removal of the 107- year-old dam, and on flooding in the lower York Creek watershed. A summary of these issues and mitigation measures with references to detailed discussion in Section 3 follows. An impact analysis is found in Section 4.
• Potentially significant and unavoidable impact to aesthetics at the Lower York Creek Reservoir. Placement of materials along the shore of the Lower York Creek Reservoir will change the water surface area (AES-NP4 in Section 3.1). A revegetation and mitigation and monitoring plan has been prepared to restore wetland and riparian habitat at the lower reservoir (Appendix 2, Lower York Creek Reservoir Revegetation and Mitigation Plan). Nevertheless, a change in the view of water surface area may be considered significant by neighbors.
• Potentially significant and unavoidable short-term impact from noise at the dam and disposal sites. Project activities will result in a temporary increase in noise at the project sites (NOI-NP2 in Section 3.9). Work will only occur during daylight hours, and efforts will be made to efficiently schedule construction activities to limit impacts to neighbors at the Lower York Creek Reservoir. The long-term benefit to the York Creek ecosystem will outweigh short-term impacts from construction.
• Significant and unavoidable impact to cultural resources through removal of this historic Upper St. Helena Dam and associated structures. The dam is a unique historical resource, significant for its role in the development of the City of St. Helena, and alteration or removal will be a significant impact (CUL-PA1 in Section 3.4). No feasible alternatives could be identified that meet the project objectives to remove the barrier to fish passage and restore habitat connectivity. Therefore, the impact is considered significant and unavoidable in order to improve the aquatic environment of York Creek for steelhead and other species.
• Potentially significant and unavoidable increase in the frequency and severity of flooding in lower York Creek due to sediment aggradation. Lower York Creek through the City has existing flood hazards, with limited areas downstream of Highway 29 regularly experiencing overbank flooding. The 2005 New Years Eve storm, a 25-year event, caused extensive flood damage to wineries, vineyards, and the Culinary Institute of America’s dormitories. Coarse material that has annually been trapped in the Upper York Creek Reservoir would be delivered to the lower reaches of York Creek (H&H-PA1 in Section 3.8). This sediment may accumulate over time in areas of reduced channel competence and locally increase flood hazards. To minimize potential impacts of sedimentation on flood capacity, a channel monitoring program by the City shall be implemented that documents changes in channel cross
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section area on a regular, pre-determined schedule; tracks sediment accumulation at bridges and other critical locations; provides guidance on acceptable levels of aggradation; and establishes a mitigation plan should channel aggradation reach a point that it significantly impacts channel capacity and flooding.
Issues to be Resolved for the No Project Alternative Issues to be resolved in the No Project Alternative include significant and unavoidable impacts to aesthetics, biological resources, global climate change, and noise.
• Potentially significant and unavoidable impact to aesthetics at the Lower York Creek Reservoir. As discussed above in the action alternatives, placement of materials along the shore of the Lower York Creek Reservoir may change the water surface area in a way that is considered significant by neighbors. (See discussion above and in AES-NP4 in Section 3.1.)
• Significant and unavoidable impact to biological resources at the Upper York Creek Reservoir. The No Project Alternative would result in two significant and unavoidable impacts to biological resources (BIO-NP1 and BIO-NP2 in Section 3.3). The Upper St. Helena Dam would continue to act as an unnatural migration barrier to fish and other aquatic species, and the Upper York Creek Dam and Reservoir would continue to disrupt the natural transport of materials and organisms, reducing their availability for downstream habitat and food and adversely affecting aquatic species and habitat. No mitigation can be provided.
• Potentially significant and unavoidable cumulative impact to global climate change. On-going actions to remove sediment and debris will increase carbon dioxide by committing the City to repeated maintenance activities (GCC-NP1 in Section 3.6). The City will seek contractors who use biodiesels and/or other emission-reducing strategies.
• Potentially significant and unavoidable impact from noise at the dam and disposal sites. As with the action alternatives, noise levels will increase due to maintenance activities. (See discussion above and in NOI-NP2 in Section 3.9.)
Additional Issue to be Resolved for the Fish Ladder Alternative In addition to the impacts to aesthetics and noise discussed for the action alternatives above, the Fish Ladder Alternative would result in a significant and unavoidable impact to biological resources. It would also involve a potentially significant cumulative impact to global climate change identified in the No Project Alternative discussion above (GCC-NP1 in Section 3.6).
• Significant, long-term, and unavoidable impact to biological resources. The fish ladder would act as a partial, unnatural, upstream and downstream migration barrier to fish and other aquatic species (BIO-FL1 in Section 3.3). The Corps estimates it
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will provide between 65% and 95% effectiveness for fish passage (Corps 2006a). No mitigation, other than on-going maintenance, is proposed.
Of the alternatives analyzed, the Small Notch is considered environmentally superior because it provides for the highest levels of ecosystem restoration and protection, while providing for greater slope stability than the Full Dam Removal Alternative. Beneficial environmental effects of the Preferred Small Notch Alternative include restored access to 1.7 miles of high quality habitat for steelhead trout; restored habitat connectivity and unimpeded migration for aquatic and terrestrial organisms; elimination of the threat of harmful low-flow fine sediment releases; and reestablished natural sediment transport processes to improve in-stream habitat in York Creek and the Napa River. Long-term impacts associated with the Preferred Small Notch Alternative include removal of an historic structure (Upper St. Helena Dam) and a possibility for changes in existing flood heights due to localized, temporary channel aggradation in lower York Creek. Construction activities are likely to produce short-term significant impacts to noise levels, traffic congestion, and aesthetics at the Upper and Lower York Creek Reservoirs.
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Table ES1. Comparison of Impacts and Mitigation Measures of Project Alternatives
Significance after Mitigation ES1 Discussion Provided in Section 3 NP-No PA-Small FR-Full FL-Fish Impact before Mitigation (Significance before Mitigation) Summary of Mitigation Project Notch Removal Ladder Aesthetics Aesthetic impacts may occur during project activities at the upper Work during daylight only; use detailed LS(B) LS(B) LS(B) LS(B) and lower reservoirs through removal of vegetation and use of construction procedures and specific BMPs. AES-NP1 AES-NP1 AES-NP1 AES-NP1 heavy equipment. (Potentially significant and short-term) Revegetate disturbed areas with native species. During maintenance or construction, placement of materials Limit disturbance and revegetate with native LS(B) LS(B) LS(B) LS(B) removed from the upper reservoir may result in aesthetic impacts species to cover sediment and blend in with AES-NP2 AES-NP2 AES-NP2 AES-NP2 at the lower reservoir. (Potentially significant and short-term) existing vegetation. Temporary aesthetic impacts from transportation of excavated Less than significant impact, none required. LS LS LS LS materials will occur during project activities. (Less than significant AES-NP3 AES-NP3 AES-NP3 AES-NP3 and short-term; see Traffic Section 3.10) Placement of materials along the shore of the lower reservoir may Native vegetation will be installed in accordance PSU PSU PSU PSU result in impacts to views of the water surface area. (Potentially with Appendix 2: Lower York Creek Reservoir AES-NP4 AES-NP4 AES-NP4 AES-NP4 significant, long-term, and unavoidable) Revegetation and Mitigation Plan.
Air Quality Asbestos dust could be released into the air during maintenance Detailed construction procedures and specific LS N/A N/A N/A activities. (Potentially significant and short-term) BMPs. AIR-NP1 (see below) (see below) (see below) Asbestos dust could be released into the air during removal of Detailed construction procedures and specific sediment and/or dam materials at the upper reservoir and during BMPs. N/A LS LS LS placement at reuse/disposition sites. (Potentially significant and (see above) AIR-PA1 AIR-PA1 AIR-PA1 short-term) Hydrogen sulfide (H2S) gas may pose a threat to air quality if it is Equip construction workers with personal H2S released during movement of sediment in the reservoir. monitoring devices. Follow OSHA construction LS LS LS LS (Potentially significant and short-term) safety protocols. If H2S levels exceed safety AIR-NP2 AIR-NP2 AIR-NP2 AIR-NP2 standards, work will stop until H2S dissipates. Project activities could result in an increase small particulate Use BAAQMD Guidelines for PM10 emission matter (PM10) emissions during sediment removal. (Potentially BMPs in SWPPP. Water active construction areas significant and short-term) at least twice daily, and wet sweep paved access LS LS LS LS roads and parking/staging areas daily. Cover trucks AIR-NP3 AIR-NP3 AIR-NP3 AIR-NP3 or require at least 2 feet of freeboard. Use BMPs to limit dust.
ES1 PA = Preferred Alternative N/A = Not Applicable LS(B) = Less than Significant (Beneficial) PSU = Potentially Significant and Unavoidable SU = Significant and Unavoidable
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Significance after Mitigation ES1 Discussion Provided in Section 3 NP-No PA-Small FR-Full FL-Fish Impact before Mitigation (Significance before Mitigation) Summary of Mitigation Project Notch Removal Ladder Biological Resources Upper St. Helena Dam would continue to act as an unnatural Impacts are significant and unavoidable. Mitigation SU migration barrier to fish and other aquatic species. (Significant is not applicable. N/A N/A N/A BIO-NP1 and long-term) The fish ladder would act as a partial, unnatural, upstream and Impacts are significant and unavoidable. Mitigation SU downstream migration barrier to fish and other aquatic species. is not applicable. N/A N/A N/A BIO-FL1 (Potentially significant and long-term) Upper York Creek Dam and Reservoir would continue to disrupt Impacts are significant and unavoidable. Mitigation the natural transport of materials and organisms, reducing their is not applicable. SU N/A N/A N/A availability for downstream habitat and food and adversely BIO-NP2 affecting aquatic species and habitat. (Significant and long-term) Future maintenance dredging or construction activities could Implement dewatering and species protection plan. result in temporary, short-term downstream sediment releases, Perform work during summer low flow conditions in kills of fish and other aquatic species, and destruction of habitat isolation from flowing water. Erosion control LS LS LS LS downstream of the dam. (Potentially significant and short-term) measures in place during construction. Require BIO-NP3 BIO-PA1 BIO-PA1 BIO-PA1 pre-construction training and monitoring by a qualified biologist during project activities. Maintenance dredging could result in direct disturbance, Implement dewatering and species protection plan. displacement, and/or mortality to non-listed aquatic species. Aquatic species relocation. Perform work during (Adverse but less than significant and short-term) summer low flow conditions in isolation from LS flowing water. Sediment control measures in place N/A N/A N/A BIO-NP4 (see below) (see below) (see below) during construction. Require pre-construction training and monitoring by a qualified biologist during project activities. Construction activities could result in direct disturbance, Implement dewatering and species protection plan. displacement, and/or mortality to non-listed aquatic species. Aquatic species relocation. Perform work during (Potentially significant and short-term) summer low flow conditions in isolation from LS LS LS flowing water. Sediment control measures in place N/A (see above) BIO-PA2 BIO-PA2 BIO-PA2 during construction. Require pre-construction training and monitoring by a qualified biologist during project activities. Maintenance dredging/construction activities could result in Pre-construction survey. Require pre-construction LS LS LS LS incidental take of California red-legged frog and foothill yellow- training and monitoring by a qualified biologist BIO-NP5 BIO-PA3 BIO-PA3 BIO-PA3 legged frog. (Potentially significant and short-term) during project activities.
ES1 PA = Preferred Alternative N/A = Not Applicable LS(B) = Less than Significant (Beneficial) PSU = Potentially Significant and Unavoidable SU = Significant and Unavoidable
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Significance after Mitigation ES2 Discussion Provided in Section 3 NP-No PA-Small FR-Full FL-Fish Impact before Mitigation (Significance before Mitigation) Summary of Mitigation Project Notch Removal Ladder Biological Resources (continued) Maintenance dredging or construction activities could result in Pre-construction survey. Require pre-construction direct disturbance, displacement, and/or mortality to special-status training and monitoring by a qualified biologist LS LS LS LS and common bat species. (Potentially significant and short-term) during project activities. Construction limited to BIO-NP6 BIO-PA4 BIO-PA4 BIO-PA4 daylight hours. Maintenance dredging or construction activities could result in both Pre-construction survey. Buffer areas established direct and indirect impacts to nesting birds as a result of nest for active nests. Monitoring by a qualified biologist LS LS LS LS destruction, mortality, and/or disturbance. (Potentially significant during project activities. BIO-NP7 BIO-PA5 BIO-PA5 BIO-PA5 and short-term) Future maintenance dredging or construction activities could result Pre-construction survey. Terrestrial wildlife species LS LS LS LS in direct disturbance, displacement, and/or mortality to terrestrial relocation. Monitoring by a qualified biologist during BIO-NP8 BIO-PA6 BIO-PA6 BIO-PA6 wildlife species. (Adverse but less than significant and short-term) project activities. Disposal of materials at Lower York Creek Reservoir and Implement wetland mitigation including creation, alteration of York Creek could result in the disturbance/loss of restoration, and/or enhancement of habitat. A 5- LS LS LS LS jurisdictional wetlands and/or other waters of the U.S. (Potentially year monitoring program is required to assure BIO-NP9 BIO-PA7 BIO-PA7 BIO-PA7 significant and long-term) success. (See Appendix 2 for details.) Maintenance dredging/construction activities could result in Plant population protective measures in place damage and/or mortality to special-status plant species if they are during project activities. Require pre-construction LS LS LS LS present within the work area. (Potentially significant and short- training. Mitigation and monitoring plan developed BIO-NP10 BIO-PA8 BIO-PA8 BIO-PA8 term) if impacts are unavoidable. Native wetland and riparian vegetation around the upper and lower implementation of revegetation and mitigation plan, reservoirs will be impacted during maintenance dredging or including removal of invasive species. (See construction, resulting in a temporary loss of habitat and Appendix 2 for details.) LS LS LS LS increasing the likelihood of establishment of invasive non-native, BIO-NP11 BIO-PA9 BIO-PA9 BIO-PA9 disturbance-adapted plant species, which could inhibit native vegetation establishment and cause a permanent loss of biotic functions and values. (Potentially significant and short-term) Native upland vegetation will be impacted during maintenance or Minimize vegetation removal. Implement construction. Removal of vegetation can result in temporary loss of revegetation plan and BMPs during construction. plant and wildlife habitat, increased erosion, and establishment of Compliance with City’s Tree Ordinance. LS LS LS LS invasive non-native plants, which could inhibit native vegetation BIO-NP12 BIO-PA10 BIO-PA10 BIO-PA10 establishment and result in a permanent loss of biotic functions and values. (Adverse but less than significant and short-term).
ES1 PA = Preferred Alternative N/A = Not Applicable LS(B) = Less than Significant (Beneficial) PSU = Potentially Significant and Unavoidable SU = Significant and Unavoidable
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Significance after Mitigation ES2 Discussion Provided in Section 3 NP-No PA-Small FR-Full FL-Fish Impact before Mitigation (Significance before Mitigation) Summary of Mitigation Project Notch Removal Ladder Cultural Resources Removal of the of UYCD and associated structures would have a Graphic and written documentation of dam’s significant adverse impact on the historic feeling, design, and significance will be posted on City’s website and SU SU SU association of a resource considered eligible for listing in the displayed in a City building. N/A CUL-PA1 CUL-PA1 CUL-PA1 National Register of Historic Places and the California Register of Historic Resources. (Significant, long-term, and unavoidable)
Geology, Soils, Landslides, and Seismic Activity Potential for project to expose people, property, or sensitive If the City selects the NP or FL Alternative, seismic natural resources to potential substantial adverse effects involving stabilization would be planned and implemented. LS LS N/A N/A strong seismic ground shaking and seismic-related ground failure, Further review under CEQA would be required. GEO–NP1 GEO–NP1 including liquefaction. (Potentially significant) Potential for project to expose people, property, or sensitive Fill existing spillway; install 2 rows of soil anchors natural resources to substantial adverse effects involving slope and subdrains. Monitoring during construction for LS N/A N/A N/A failure due to removal of the dam at the toe of a landslide. slope stability and possible defects; use of GEO–PA1 (see below) (Potentially significant) supplemental stabilization measures if needed. Potential for project to expose people, property, or sensitive Install 3 rows of soil anchors and subdrains. natural resources to substantial adverse effects involving slope Monitoring during construction for slope stability N/A LS N/A N/A failure due to removal of the dam at the toe of a landslide. and possible defects; use of supplemental (see above) GEO–FR1 (Potentially significant) stabilization measures if needed.
Global Climate Change On-going actions to remove sediment and debris will increase Use of biodiesels or other emission-reducing PSU PSU carbon dioxide by committing the City to repeated maintenance strategies. N/A N/A GCC-NP1 GCC-NP1 activities. (Potentially cumulatively significant and long-term) (see below) Action alternatives will generate carbon dioxide over the short Implement revegetation plan to reduce carbon LS(B) LS(B) LS(B) N/A term. (Potentially cumulatively significant and short-term) dioxide output to negative levels. GCC-PA1 GCC-FR1 GCC-FL1
Hazardous Materials Potential for exposure of construction workers to unsafe levels of Equip at least one worker in each construction area LS LS LS LS hydrogen sulfide (H2S). (Potentially significant) with personal H2S monitoring device. Follow OSHA HAZ-NP1 HAZ-NP1 HAZ-NP1 HAZ-NP1 safety protocols. If H2S levels exceed safety standards, work will stop until H2S dissipates.
ES1 PA = Preferred Alternative N/A = Not Applicable LS(B) = Less than Significant (Beneficial) PSU = Potentially Significant and Unavoidable SU = Significant and Unavoidable
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Significance after Mitigation ES3 Discussion Provided in Section 3 NP-No PA-Small FR-Full FL-Fish Impact before Mitigation (Significance before Mitigation) Summary of Mitigation Project Notch Removal Ladder
Hazardous Materials (continued) Potential for standard toxics associated with construction vehicle Detailed construction procedures and specific LS LS LS LS operation to be released into the environment. (Potentially BMPs for spill prevention. HAZ-NP2 HAZ-NP2 HAZ-NP2 HAZ-NP2 significant and short-term) Asbestos may become airborne through earthmoving activities Detailed construction procedures and specific LS LS LS during dam removal creating a health hazard for construction BMPs for dust control. N/A HAZ-PA1 HAZ-PA1 HAZ-PA1 workers. (Potentially significant and short-term)
Hydrology and Hydraulics On-going sedimentation of the Upper York Creek Reservoir may City shall continue the regular removal of sediment LS threaten dam functioning and stability in the NP Alternative. in the reservoir. N/A N/A N/A H&H-NP1 (Potentially significant and long-term) Failure of Upper St. Helena Dam could result in loss of life, City shall have Upper St. Helena Dam evaluated property damage, and/or streambed aggradation. (Potentially for stability and shall implement recommended LS N/A N/A N/A significant and long-term) seismic stabilization measures. (See Mitigation H&H-NP2 GEO-NP4.) Sediment aggradation in lower York Creek may increase the City shall implement channel monitoring program, PSU PSU PSU frequency and severity of flooding. (Potentially significant and causative factors analysis, and program to improve N/A H&H-PA1 H&H-PA1 H&H-PA1 long-term) channel capacity and promote sediment transport. Construction activities may lead to streambank erosion within the Install erosion control measures, including rock project site. (Potentially significant and short-term) and/or bioengineered bank protection to the 100- LS LS LS N/A year flow elevation (Civil Design Appendix (B) of H&H-PA2 H&H-PA2 H&H-PA2 the Final Draft Project Report (Corps 2006a)).
Noise Truck traffic from project activities could temporarily increase Less than significant impact, none required. LS LS LS LS noise levels on Spring Mountain Road. (Less than significant) NOI-NP1 NOI-NP1 NOI-NP1 NOI-NP1 Maintenance or construction activities would temporarily increase Work will occur during daylight hours, and efforts PSU PSU PSU PSU noise at the dam and disposal sites. (Potentially significant, short- will be made to efficiently schedule construction NOI-NP2 NOI-NP2 NOI-NP2 NOI-NP2 term, and unavoidable) activities to limit impacts to neighbors
ES1 PA = Preferred Alternative N/A = Not Applicable LS(B) = Less than Significant (Beneficial) PSU = Potentially Significant and Unavoidable SU = Significant and Unavoidable
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Significance after Mitigation ES4 Discussion Provided in Section 3 Impact before Mitigation (Significance before Mitigation) Summary of Mitigation NP-No PA-Small FR-Full FL-Fish Project Notch Removal Ladder Traffic and Transportation Trucks entering and leaving Spring Mountain Road may cause Contractors shall provide traffic control plan using LS LS LS LS traffic delays. (Potentially significant and short-term) standard Caltrans protocols, including flaggers. TRA-NP1 TRA-NP1 TRA-NP1 TRA-NP1 Emergency vehicles shall be given priority. Trucks moving materials from reservoir to reuse or disposal sites Less than significant impact, none required. LS LS LS LS will contribute to traffic loads on the roads. (Less than significant) TRA-PA1 TRA-PA1 TRA-PA1 TRA-PA1 The project could generate peak hour traffic to roads that exceed Construction traffic will only travel to disposition N/A LS LS N/A acceptable level of service (LOS). (Potentially significant and sites on Spring Mountain Road before 9 am and TRA-PA2 TRA-PA2 short-term) after 3 pm to avoid contributing to peak hour traffic.
Water Quality Water quality in York Creek could be degraded during project The Basin Plan standards shall be used as a LS LS LS LS maintenance or construction activities and result in adverse effects guideline for monitoring and compliance unless WQ-NP1 WQ-NP1 WQ-NP1 WQ-NP1 to downstream aquatic life. (Potentially significant and short-term) more stringent permit conditions are imposed. Monitoring is required upstream and downstream of the project area at least once daily during any activity that could impact water quality. Project activities could result in increased turbidity that adversely Adhere to SWPPP and dewatering and species LS LS LS LS affects water quality downstream of the dam to the Napa River. protection plan. Turbidity shall be monitored to WQ-NP2 WQ-NP2 WQ-NP2 WQ-NP2 (Potentially significant and short-term) verify impacts have been avoided. Naturally-occurring asbestos could be released into York Creek Less than significant impact, none required. LS LS LS LS from sediment movement during maintenance or construction WQ-NP3 WQ-NP3 WQ-NP3 WQ-NP3 activities in the reservoir. (Less than significant) Hydrogen sulfide (H2S) could be released into York Creek from an H2S levels shall be monitored to ensure they do not LS LS LS LS accidental spill during sediment removal. (Potentially significant exceed background upstream of the construction WQ-NP4 WQ-NP4 WQ-NP4 WQ-NP4 and short-term) area. If levels are exceeded, work shall be halted until measurements return to background levels. Monitoring is required upstream and downstream of the project area at least once daily during any activity that could result in the release of H2S.
ES1 PA = Preferred Alternative N/A = Not Applicable LS(B) = Less than Significant (Beneficial) PSU = Potentially Significant and Unavoidable SU = Significant and Unavoidable
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1 Proposed Action
1.1 Project Description and Objectives The Upper York Creek Ecosystem Restoration Project is jointly sponsored by the City of St. Helena (City) and the U.S. Army Corps of Engineers (Corps). The project involves alteration or removal of the Upper St. Helena Dam and restoration of the former reservoir area into a natural creek channel and native riparian corridor. Project objectives include:
• Improved fish passage and habitat connectivity. The project will provide upstream passage to 1.7 miles of spawning and rearing habitat for steelhead (Oncorhynchus mykiss) and habitat connectivity for both anadromous and resident fish and other aquatic and riparian species.
• Reduced future downstream habitat degradation and fish kills. The project will prevent potentially detrimental sediment releases during summer low-flow conditions that have caused fish and aquatic organism kills in the past. It will provide a permanent solution to prevent short-term aquatic habitat impairment associated with possible dam breach/failure.
• Habitat restoration. The project will restore approximately 3 acres of degraded riparian and aquatic habitat within the existing upper dam and reservoir area. Restoration of natural sediment transport processes will occur through the project site, with potential habitat improvement occurring in downstream reaches of York Creek and the Napa River. Disturbed areas in the project site will be revegetated with a palette of multistory native plants. A diversity of habitats for aquatic, riparian, and terrestrial animals will be provided.
1.2 Project Location The proposed project is located on the western edge of the Napa Valley near the City of St. Helena. The Napa River runs north to south on the east side of the City, and several of its tributaries flow through the City eastward from the hills of the Mayacmas Mountains. The primary project site is on York Creek, which is one of these tributaries. The proposed project will take place at the Upper York Creek Dam and Reservoir (Upper St. Helena Dam), which is located at 38º 30’ 48” N, 122º 30’ 9” W, in the SW ¼, Section 26, Range 6 West, Township 8 North, Mt. Diablo Base and Meridian of the USGS St. Helena Quadrangle, St. Helena, Napa County, California (Figure 1). The project area is zoned AW (Agriculture, Watershed or Open Space Lands).
The project area also includes 3 ancillary sites that are under consideration for reuse or disposal of materials removed during project activities: an adjacent private vineyard, Lower York Creek Reservoir (LYCR or lower reservoir), and Clover Flat landfill. Spring Mountain Vineyard (SMV) is accessed from 2805 Spring Mountain Road, which is located approximately 0.5 miles downhill and south of the upper reservoir; there is also an access road approximately 0.5 miles uphill. The lower reservoir is located less than 0.5 miles downhill on the east side of Spring Mountain Road. Clover Flat is located at 4380 Silverado Trail near Calistoga, 8.5 miles north of the main project site.
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1.3 Characteristics of the Project Area York Creek runs approximately 7.24 miles from its headwaters to its confluence with the Napa River (Corps 2006b). It descends steeply over the first portion of its range then flattens out as it crosses the floodplain of the Napa River. It drains a watershed of approximately 4.4 square miles (Watershed Information and Conservancy Center of Napa County). At the site of the upper reservoir, York Creek traverses a steep valley cut from serpentinite and sheared shale. Vegetation is a mixture of redwood forest, mixed evergreen forest, riparian woodland, foothill pine-oak woodland, freshwater wetland, non-native grassland, vineyards, and ruderal areas.
According to the Napa County Resource Conservation District (NCRCD), York Creek is one of the most significant spawning and rearing streams in the Napa River watershed for Central California Coast ESU steelhead, which are listed as threatened under the federal Endangered Species Act. It has been designated as critical habitat for steelhead by NOAA Fisheries Service. The Napa River watershed is considered one of the key anadromous fish streams within the San Francisco Bay (NCRCD 2005).
The Upper St. Helena Dam is a total barrier to fish passage. It is comprised of an earthen structure, 140 feet wide and 50 feet high. The outlet is a standpipe that collects water near the downstream edge of the reservoir and discharges it through a stone culvert in the bottom center of the dam. The reservoir behind the dam is full of sediment (approximately 28,000 cubic yards, essentially eliminating any water storage capacity) and is no longer used to provide water for the City’s needs. The dam itself is made up of approximately 12,000 cubic yards of material. (Corp 2006a)
There are two spillways: the original on the south and a newer, functioning spillway between the reservoir and Spring Mountain Road that was built in 1933. The left wall of the newer spillway (looking downstream) provides structural support to the road, which connects St. Helena to Santa Rosa in Sonoma County.
The reuse site at Spring Mountain Vineyard is a fallow field adjacent to the upper reservoir that will be replanted with grape vines. Lower York Creek Reservoir currently has a storage capacity of approximately 156 acre-feet; it provides untreated water for a portion of the City’s agricultural irrigation and construction water demands. The approved disposal facility being considered is Clover Flat landfill, which is located approximately 8.5 miles from the upper reservoir.
1.4 Project Background and History York Creek was first dammed in 1871. The current dam was built upstream of the original reservoir in 1900 to extend the City’s water delivery system to match its expanding development (Eastman 2003). In 1933, a new concrete overflow spillway was added along the eastern edge of the reservoir and dam immediately adjacent to Spring Mountain Road, the crest of the dam was raised 15 feet to its current height of 50 feet, the standpipe outlet was installed, and other incidental modifications were made.
On July 28, 1992, during routine maintenance of the reservoir outlet, there was an accidental sediment discharge downstream of the dam. This significant release resulted in a silt discharge within the streambed from the face of the dam to York Creek’s confluence with the Napa River.
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The depth of the silt varied from heavy deposits (up to 18 inches) just below the dam and continuing downstream for about 0.5 miles, gradually thinning until only a light covering of fine silt was deposited at the confluence with the Napa River. According to a CDFG letter dated July 30, 1992, this sediment release was the fourth since 1965. In each incidence, “dense anaerobic sediments, high in toxic hydrogen sulfide, were released from the dam and deposited in pools and riffle areas downstream, quickly suffocating and burying all fish and aquatic invertebrates within a mile or more of the dam.”
After this discharge, CDFG filed a complaint with the Napa County District Attorney. In September of 1992, CDFG and the City concluded that the City should remove the existing earthen dam structure on York Creek. An agreement was signed obligating the City to remove the dam, stabilize silt, remove silt that had filtered downstream, and take certain precautions to preserve the stability and natural character of the area.
In October 1993, the City applied to the Corps Regulatory Branch for a federal Clean Water Act Section 404 permit to remove the dam. This application and a revised application in 1994 were determined to be incomplete. At the time of the initial 1993-1994 coordination with the Corps, steelhead in the central California coast Evolutionarily Significant Unit (CCC ESU) were not yet listed pursuant to the federal ESA, and the Corps was not obligated to initiate consultation with NOAA Fisheries Service.
On August 18, 1997, NOAA Fisheries Service listed CCC ESU steelhead as threatened with loss of habitat and threats to their current range. In August of 1998, the City sent a letter to Corps Regulatory Branch requesting that they reactivate the previous permit application for dam removal. This request was declined, citing lack of adequate information to evaluate impacts to the aquatic environment from the project.
In October 2000, a letter was sent from NOAA Fisheries Service law enforcement to the City Manager that provided clarification about the City’s potential liabilities under the ESA if the Upper St. Helena Dam were to remain in place. On November 21, 2000, the City Attorney sent NOAA Fisheries Service, Corps Regulatory Branch, CDFG, and the Napa County District Attorney a letter explaining that it was the City Council’s position that the Upper St. Helena Dam should at least be breached to allow fish passage and that “the downstream diversion structure should be modified so that it is not a barrier or impediment to the passage of steelhead 5.”
Representatives from NOAA Fisheries Service, the City, Department of Water Resources (DWR), CDFG, Corps Regulatory, Corps Civil Works, and the Napa County District Attorney’s Office attended a meeting in early 2001 to discuss the project. DWR representatives stated their intention to assist the City by providing planning and permitting services for the project to modify the diversion structure and to remove the Upper St. Helena Dam. Because in-stream work and dewatering were necessary to correct the adverse effects on steelhead, NOAA Fisheries Service advised that the dam removal or modification project would require formal consultation under Section 7 of the federal ESA.
5 The City removed the lower diversion in 2004. One-half mile of aquatic habitat was opened to the base of the Upper St. Helena Dam. The modifications involved removal of the concrete structure, creation of cascading steps with resting pools, bank stabilization, and revegetation with native species.
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In November of 2001, a meeting was held at the City’s Offices for DWR to give an update on the status of project planning and design. Representatives from NOAA Fisheries Service, the City, DWR, CDFG, Corps Civil Works, and U.S. Fish and Wildlife Service attended. This meeting initiated the partnership between the City and Corps Civil Works for implementation of the ecosystem restoration project that is the subject of this document.
1.5 Environmental Process and Timeline The National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA) require federal agencies and state and local agencies, respectively, to consider and disclose potential impacts to the environment from their actions. The Corps is the Lead Agency under NEPA. On December 15, 2006, the Corps published the Final Draft Detailed Project Report for the Upper York Creek Ecosystem Restoration Project, Napa County, California (Corps 2006a), which presents the findings of the alternatives analysis and the selection of a recommended plan for the Upper York Creek Ecosystem Restoration Project. Because the project involves a federal action, and because no categorical exclusion applies for this type of action, the Corps prepared the Upper York Creek Ecosystem Restoration Project Environmental Assessment, which addresses the direct and indirect environmental effects the proposed action may have upon the human environment (Corps 2006b). Both of these documents and their appendices are available for review on the City’s website at www.ci.st-helena.ca.us/.
Specific details of the conceptual design for the Upper York Creek Ecosystem Restoration Project are found in the above-mentioned documents that were prepared by the Corps as part of the feasibility analysis and NEPA compliance (Corps 2006a and Corps 2006b, respectively). The DEIR and its associated background documentation are also available for review on the City’s website and at the St. Helena Public Library, 1492 Library Lane, St. Helena, CA 94574. Contact information is provided below.
1.5.1 Project Sponsors Non-federal Sponsor City of St. Helena 1480 Main Street St. Helena, CA 94574
Federal Sponsor U.S. Army Corps of Engineers San Francisco District, South Pacific Division 1455 Market Street San Francisco, CA 94103-1398
1.5.2 CEQA Lead Agency City of St. Helena 1480 Main Street St. Helena, CA 94574
Contact Jonathon Goldman, Director of Public Works/City Engineer
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(707) 968-2658 [email protected]
1.5.3 CEQA Responsible and Trustee Agencies In addition to the project sponsors, a number of agencies are responsible for review of the findings of the CEQA Lead Agency. These include:
Bay Area Air Quality Management District California Department of Fish and Game California Regional Water Quality Control Board, San Francisco Bay Region California Office of Historic Preservation Napa County Public Works The Resources Agency
1.5.3.1 Other Commenting Agencies Although the agencies listed below are not mandated by law to review the findings in the DEIR, comments will be solicited and considered from the following and from others upon request:
Caltrans Napa County Resource Conservation District Native American Heritage Commission NOAA’s National Marine Fisheries Service U.S. Army Corps of Engineers, Regulatory Branch U.S. Environmental Protection Agency U.S. Fish and Wildlife Service
1.5.4 Public Participation and Timeline A Notice of Preparation (NOP) of a Draft Environmental Impact Report for the Upper York Creek Ecosystem Restoration Project was published by the State Clearinghouse on September 19, 2006 (SCH# 2006092096; Appendix 3). Public comment closed on October 18, 2006, and no comments were received. The City participated in a public meeting hosted by the Corps on September 21, 2006, where comments were received from the Friends of the Napa River regarding their support for installation of native plantings as part of the restoration project.
In addition to comments from public agencies, the City seeks comments from the general public on this DEIR for the proposed project and its potential impacts. The public comment period will extend from Friday, April 20, 2007, through Monday, June 4, 2007. Comments should be addressed to:
Jonathon Goldman, Director of Public Works/City Engineer City of St. Helena 1480 Main Street St. Helena, CA 94574 (707) 968-2658 [email protected]
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The DEIR and its supporting documentation are available electronically on City’s website at www.ci.st-helena.ca.us/ and at the St. Helena Public Library, 1492 Library Lane, St. Helena, CA 94574.
1.5.5 Timeline for Project Implementation The Corps plans 3 years of construction starting in August 2007 and ending in October 2009. Initiation of pre-construction monitoring is scheduled for July 2007. Monitoring will continue through October 2012. (Corps 2006a)
1.6 Regulatory Background for the Project In addition to NEPA and CEQA, the proposed project is subject to a number of laws and regulations that are designed to protect the environment. A number of ecological permits are required that are summarized below. Compliance with a new California law that addresses global warming and climate change includes analysis of the project’s potential contributions to greenhouse gases in Section 3.6 of this DEIR.
1.6.1 Ecological Permits Work in creeks and rivers in California is regulated by several public agencies, including the Corps, the Regional Water Quality Control Boards (RWQCB), CDFG, and the local city or county where the project takes place (e.g., grading, zoning, or building permits). Potential impacts to listed species are regulated under the state and federal Endangered Species Acts. The Bay Area Air Quality Management District (BAAQMD) has jurisdiction over activities that may result in impacts to air quality. A Storm Water Pollution Prevention Plan (SWPPP) will be prepared and implemented during project activities. The project will require the following ecological permits for implementation:
1.6.1.1 U.S. Army Corps of Engineers §404 Nationwide or Individual Permit Under §404 of the federal Clean Water Act, the Corps regulates discharges of dredged or fill material into any channel that is a navigable water of the U.S. or its tributary or that has real or potential interstate commerce value. A channel is defined as a watercourse that has a bed and bank with an ordinary high water mark (OHWM).6 Functionally, the Corps regulates nearly all creeks and rivers. Nationwide Permits (NWPs) have been developed to allow implementation of projects that meet specific criteria and that do not result in adverse environmental effects; other projects that do not meet the criteria for a NWP must apply for an Individual Permit.
1.6.1.2 Regional Water Quality Control Board §401 Certification Under §401 of the federal Clean Water Act, the Corps is required to meet state water quality regulations prior to granting a §404 permit for work in a creek or river. In California, this is accomplished by application to the local RWQCB for certification that the requirements have been met. This project will occur within the jurisdiction of the San Francisco Bay RWQCB (SFBRWQCB).
6 The ordinary high water mark (OHWM) is described as the elevation delineating the highest water level that has been maintained for a sufficient period of time to leave evidence on the landscape. This demarcation may be a change in vegetation or soil, the presence of debris, etc. It is subjective and is determined by the Corps Regulatory Branch.
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1.6.1.3 California Department of Fish and Game §1602 Streambed Alteration Agreement Under §1600, et seq., of the California Fish and Game Code, CDFG has jurisdiction over any activity in a creek or river in which there is at any time an existing fish or wildlife resource or from which such resources derive benefit. Projects affecting or potentially affecting such resources must obtain a Streambed Alteration Agreement from CDFG. The agreement will impose general and site-specific conditions to protect the environment.
1.6.1.4 Endangered Species Act Compliance Under the federal Endangered Species Act (FESA), the Secretary of the Interior and the Secretary of Commerce have joint authority to list a species as threatened or endangered. Two federal agencies oversee the FESA: the U.S. Fish and Wildlife Service (USFWS), a part of the Department of the Interior, has jurisdiction over plants, wildlife, and resident fish, while NOAA’s National Marine Fisheries Service (NOAA Fisheries Service), a part of the Commerce Department, has jurisdiction over anadromous fish and marine fish and mammals. Section 7 of the FESA mandates that all federal agencies consult with USFWS and NOAA Fisheries Service to ensure that federal agency actions do not jeopardize the continued existence of a listed species or destroy or adversely modify critical habitat for listed species.
The FESA prohibits “take” of any fish or wildlife species listed as threatened or endangered, including the destruction of habitat that could hinder species recovery. Section 10 of the FESA requires the issuance of an incidental take permit before any public or private action may be taken that would potentially result in “take,” which is defined as actions that would potentially harm, harass, injure, kill, capture, collect, or otherwise hurt any individual of an endangered or threatened species.
Under the California Endangered Species Act (CESA), CDFG is responsible for maintaining a list of endangered and threatened species. The list also includes federally proposed and state candidate species, which are species that CDFG has formally noticed as being under review for addition to either the list of endangered species or the list of threatened species, as well as fully protected species for which “take” may be authorized only for recovery activities. CDFG also maintains lists of California special concern species that serve as watch lists. Pursuant to the requirements of CESA, an agency reviewing a proposed project within its jurisdiction must determine whether any state-listed as endangered or threatened species may be present in the project area and determine whether the proposed project will have a potentially significant impact on such species. In addition, CDFG encourages informal consultation on any proposed project that may affect candidate species.
The Corps responsibilities include consultation with USFWS and NOAA Fisheries Service when federally listed species are at risk. At both the state and federal levels, the process requires that a Biological Assessment be prepared to determine the effects on listed species (Corps 2006b). The Corps, the project’s federal partner, has requested preparation of Coordination Act Reports (CAR) by both USFWS and NOAA Fisheries Service. (See discussion in Section 1.6.2, Fish and Wildlife Coordination Act, below.)
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1.6.1.5 Bay Area Air Quality Management District Permit Air quality and emissions are regulated by the California Air Resources Board (CARB), a part of the California Environmental Protection Agency (CalEPA). Under the CARB, the state is divided into 15 local air districts that have primary responsibility for controlling air pollution from stationary sources. The project will take place under the jurisdiction of the Bay Area Air Quality Management District (BAAQMD). The BAAQMD’s Asbestos Airborne Toxic Control Measure (ATCM) for Construction provides the guidelines for controlling airborne asbestos. An Asbestos Dust Mitigation Plan will be required from BAAQMD to comply with the ATCM (Section 3.2, Air Quality).
1.6.1.6 Storm Water Pollution Prevention Plan (SWPPP) Compliance with the National Pollutant Discharge Elimination System (NPDES) of the Clean Water Act requires a permit for storm water discharges associated with construction activity. For all construction projects disturbing an area greater than one acre, a Notice of Intent (NOI) must be filed with the SWRCB. Each NOI requires a Storm Water Pollution Prevention Plan (SWPPP) be developed and implemented. The SWPPP will identify potential storm water discharges from construction activity and assign Best Management Practices (BMPs) to limit negative impacts to water quality.
1.6.1.7 City of St. Helena The City of St. Helena’s Municipal Code Title 15, Chapter 15.52 Flood Damage Prevention provides for the establishment of areas of special flood hazard through scientific studies and mapping, as recommended by the City floodplain administrator. The floodplain administrator has the responsibility to manage activities that affect flooding and maintain the carrying capacity of channels within, or affecting properties within, City limits. See Hydrology and Hydraulics Section 3.8 for discussion of flooding issues.
1.6.2 Fish and Wildlife Coordination Act The Fish and Wildlife Coordination Act (16 USC §661, et seq.) requires federal agencies to coordinate with USFWS, applicable state agencies, and NOAA Fisheries Service, as appropriate, when modification of a stream or body of water is proposed. The intent is to give fish and wildlife conservation equal consideration with other purposes of water resources development projects. Coordination with USFWS, NOAA Fisheries Service, and CDFG has occurred throughout the planning process for the Upper York Creek Ecosystem Restoration Project, and a Coordination Act Report (CAR) will be prepared.
1.6.3 National Historic Preservation Act The National Historic Preservation Act of 1966 (NHPA) established the National Register of Historic Places (NRHP), a listing of prehistoric and historic archaeological sites, buildings, districts, structures, and objects significant in American history, architecture, archaeology, engineering, and culture. Section 106 of NHPA requires federal agencies to “take into account” the effects of a proposed project on cultural resources listed in the NRHP or those determined eligible for listing through a consensus-based process between the State Historic Preservation Officer (SHPO) and the federal agency. Such cultural resources may be of local, regional, state, or national significance, and are referred to as “historic properties.” Taking into account a project's effects typically involves identifying cultural resources, determining whether they
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meet the criteria of the NRHP, and, if eligible, mitigating any adverse effects caused by project construction. This process of implementing the provisions of §106, outlined in regulations issued by the Advisory Council on Historic Preservation (36 CFR Part 800), requires consultation between the federal agency and SHPO, and often involves participation by a federally recognized tribe, other Indian groups, and various parties who express an interest in the affected historic properties.
1.6.4 Migratory Bird Treaty Act Under the Migratory Bird Treaty Act (MBTA), it is unlawful to take, kill, and/or possess migratory birds at any time or in any manner, unless the appropriate permits are obtained. Protections extend to active nests, eggs, and young birds still in the nest. Most bird species, with a few specific exceptions, are protected under this act. Construction activities during the breeding period, typically mid-March to mid-August in this region (RHJV 2004), could result in losses to these and other native wildlife species. To avoid potential losses to nesting migratory birds, construction activities should occur outside of the critical breeding period, or avoidance measures discussed in the Biological Resources section (3.3) will be implemented under the guidance of CDFG.
1.6.5 California Global Warming Solutions Act of 2006 In 2006, the state of California enacted Assembly Bill 32 (AB 32), the California Global Warming Solutions Act of 2006. The law states, “Global warming poses a serious threat to the economic well-being, public health, natural resources, and the environment of California.” The law codifies the greenhouse gas reduction to 1990 levels by 2020, transfers leadership of the interagency cooperation to the Air Resources Board, implements mandatory reporting by industry of greenhouse gas emissions, requires voluntary, regulatory, and market incentive mechanisms for reducing greenhouse gases, and adopts early implementation actions.
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2 Alternatives Considered for the Project
2.1 All Alternatives Considered Before preparation of this DEIR, the Corps prepared a feasibility study for the removal and/or modification of the Upper St. Helena Dam (Corps 2006a). In the feasibility study, several approaches to the project design were analyzed at a conceptual level in order to determine the alternative that best meets the overall project objectives of improved fish passage and habitat connectivity, reduced future downstream habitat degradation and fish kills, and riparian and aquatic habitat restoration. In addition, each alternative had to maintain the stability of the adjoining Spring Mountain Road. The Corps evaluated seven preliminary alternatives:
• No Project. • Modify (notch or lower) dam to streambed level to create hydrologic connectivity. • Remove the dam and build support structure for slope stability. • Modify (notch or lower) the dam partway and build a fish ladder. • Re-route York Creek around the dam. • Remove the dam; re-route Spring Mountain Road to avoid slope stability issues. • Build a fish ladder over the unmodified dam.
The last three were eliminated early in the analysis. Re-routing the creek around the dam would require blasting through the landslide-prone canyon into another watershed. This alternative was rejected because it did not meet objectives for fish passage and habitat improvement, and it is not cost-effective. Re-routing Spring Mountain Road was considered unfeasible because there is no alternate route through the narrow canyon. Leaving the 50-foot dam in place and constructing a fish ladder over it was found to be ineffective in providing for fish passage as well as cost-prohibitive. The most suitable fish passage structures for this alternative are Denil or Steeppass fishways—both of which would need to be so steep that they would be difficult for fish to navigate and would require significant, regular maintenance.
The following project alternatives were selected by the Corps for further development during the feasibility phase of the project:
• Corps Alternative 1: Remove the dam to create hydrologic connectivity and build support structure for slope stability. • Corps Alternative 2: Modify (notch) the dam to streambed level to create hydrologic connectivity. • Corps Alternative 3: Modify (notch) the dam partway and build a fish ladder.
Alternative 2 was further split into two possibilities: A) large notch in the dam allowing for some floodplain through the dam area and B) small notch resulting in a 23-foot wide channel without a floodplain. Subsequent investigation into the large notch revealed that slope stability issues would only allow a 1.5-foot floodplain. Alternative 2A was dropped from additional analysis because it cost more than 2B and provided little or no additional ecological benefit. (Corps 2006a)
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2.2 Alternatives Analyzed in DEIR Based upon this analysis by the Corps, the City is currently considering a No Project and 3 action alternatives. Discussion of each alternative in relation to specific environmental resources is provided in Section 3. Figures 2-5 provide a cross sectional rendering and plan views of the three action alternatives. For cross-referencing with Corps documents, these alternatives are identified as follows:
Table 1. Corps and City Project Alternatives
U.S. Army Corps of Engineers City of Saint Helena No Project No Project (NP) Alternative 1 Full Dam Removal (FR) Preferred Alternative 2B Small Notch (PA) Alternative 3 Fish Ladder (FL)
The alternatives are briefly described below. Section 2.3 contains fuller descriptions of elements common to each of the action alternatives.
2.2.1 No Project Consideration of the No Project Alternative, which describes the circumstance under which the proposed action would not occur, is required even if it does not meet the project objectives (CCR §15126(f)). The purpose of describing and analyzing a No Project Alternative is to allow the public and agency decision-makers to compare the impacts of approving the proposed project with impacts should the project not be approved. Analysis of impacts of the No Project Alternative includes activities that would reasonably be expected to occur in the foreseeable future if the proposed project were not approved.
Under the No Project Alternative, the historic Upper St. Helena Dam would not be altered from its current configuration. Fish passage and habitat connectivity would not be restored, and no ecosystem restoration measures would be implemented. Regular maintenance dredging of the reservoir would be required to offset the continued deposition of materials behind the dam and to prevent sediment releases.
2.2.2 Small Notch The Small Notch Alternative would restore the ecological connectivity between habitats above and below the dam and allow for natural sediment transport. It would provide the same level of steelhead passage as the natural upstream and downstream reaches of York Creek. It allows for the removal of 95% of sediment behind the dam, reducing the threat of future sediment releases, and removal of 72% of the dam material itself. (Corps 2006a)
The existing spillway structure and dam embankment currently help support Spring Mountain Road and stabilize the adjacent landslide. In the Small Notch Alternative, the spillway would remain in place and be filled with materials excavated from the project area. Based on the initial feasibility analysis, 2 rows of inclined screw anchors (geotechnical slope stability tools) would be installed 50 to 100 feet into the ground for further stability (Corps 2006a). The actual number of rows of anchors would be determined upon completion of the final investigation and design.
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A geotechnical monitoring program is currently underway to quantify the actual ground movement at the site.
Notching the dam would generate approximately 40,000 cubic yards of materials: 800 cubic yards from below the dam, 12,000 cubic yards of dam material, and 27,000 cubic yards of sediments (Corps 2006a). The streambanks of the notch cut through the dam would be stabilized with vegetated rock slope protection on the left bank (looking downstream) and a willow brush mattress on the right bank. A 23-foot wide natural stream channel would be restored from immediately below the dam to just above the reservoir with a slope of approximately 5%(Corps 2006a).
The Small Notch Alternative includes installation of native plants for erosion control and habitat restoration. Planting would include 0.4 acres of bank zone, 0.5 acres of terrace zone, and 1.1 acres of riparian influenced slope for a total of 2.0 acres of restored riparian habitat acreage. In addition, 1.5 acres of spawning and rearing habitat would be made available to steelhead.
Figure 2. Conceptual Cross Sections of Action Alternatives
Based on Corps 2006a Engineering Appendix
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2.2.3 Full Dam Removal The Full Dam Removal Alternative is also designed to restore the ecological connectivity between habitats upstream and downstream of the dam and provide for natural sediment transport. Steelhead migration would be restored to the level provided by the natural channels above and below the dam. This alternative allows for the removal of 100% of sediment behind the dam, eliminating the threat of future sediment releases, and removal of nearly 100% of the actual dam material (Corps 2006a).
The Full Dam Removal alternative would completely remove the spillway and the dam embankment and, therefore, require greater slope reinforcement measures than are needed for the Small Notch Alternative. Initial analysis indicates that 3 rows of screw anchors installed 50 to 100 feet into the ground would be required to stabilize the site. As in the Small Notch Alternative, the actual number of rows of anchors will be determined upon completion of the final investigation and design (Corps 2006a).
The Full Dam Removal Alternative includes natural channel restoration of York Creek from just below the dam to immediately above the reservoir with a slope of approximately 5%. In addition to a 23-foot wide natural stream channel, a 30-foot wide floodplain could also be constructed through the former dam and reservoir. Although floodplains are not common in the upper portions of the York Creek watershed, such a terrace could provide additional riparian habitat. One hundred percent of the dam material and sediment currently accumulated behind the dam would be removed. It is estimated that total removal of the dam and reservoir sediments would generate 45,000 cubic yards of materials: 1,000 from downstream, 16,000 from the dam area, and 28,000 from reservoir sediments (Corps 2006a). The Full Dam Removal Alternative would include restoration of approximately 3 acres of aquatic and riparian habitat with native vegetation, and revegetation with native plants for erosion control and site stabilization. Plantings would include 0.4 acres of bank zone, 0.6 acres of terrace zone and 1.2 acres of riparian influenced slope for a total of 2.2 acres (Corps 2006a). As in the Small Notch Alternative, an additional 1.5 acres of spawning and rearing habitat would be made available to steelhead. 2.2.4 Fish Ladder The Fish Ladder Alternative consists of a concrete step-pool/weir fish ladder cut through the notch and over the dam, and a reconstructed natural channel upstream of the ladder through the former reservoir. The dam level would be lowered 20 feet and the spillway filled with excavated material. The fish ladder would then be built over the remaining dam to connect with the existing downstream channel. The slope of the structure over the dam would be 23%. The ladder would be 23 feet wide, constructed of boxes 4 feet wide by 5 feet long by 20 inches high with a jump height of 12 inches or less. (Corps 2006a)
The Corps has estimated that the Fish Latter Alternative would be 65-95% effective for steelhead passage (Corps 2006a). Although the ladder would be designed for all steelhead life stages, passage is also dependent on flow levels. Since the dam is no longer used to maintain and manage water releases, flows through the ladder cannot be regulated for optimal year- round movement of steelhead and other wildlife. Fish passage would likely be restricted to the rainy season (December through April). In the summer, the ladder would limit or block
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downstream migration of smolts, as well as local migration and dispersal of other aquatic species. In addition, the fish ladder is expected to clog with sediment and debris 4 to 7 times each winter, thereby further restricting steelhead passage (Corps 2006a).
The Fish Ladder Alternative allows for the removal of 37% of the sediment behind the dam and removal of 52% of the actual dam structure. The alternative offers limited sediment transport, which paradoxically improves when the ladder is allowed to fill up with debris. The Fish Ladder Alternative would have little impact on the existing support structures for Spring Mountain Road, and, therefore, no additional geotechnical stabilization measures would be required (Section 3.5, Geology, Soils, Landslides, and Seismic Activity).
Construction of the fish ladder would generate approximately 19,000 cubic yards of materials: 1,000 from downstream of the dam, 8,000 cubic yards of dam material, and 10,000 yards of sediment (Corps 2006a).
Upstream of the ladder, a stream channel would be reconstructed on top of approximately 12 feet of sediment with a gradient of 3% instead of the 5% gradient in both the Small Notch and Full Removal Alternatives. Slopes created by sediment removal would be planted with native trees and shrubs. The Fish Ladder Alternative would include 0.4 acres of bank zone, 0.9 acres of terrace zone, and 0.6 acres of riparian influenced slope for a total of 1.9 acres of restored habitat acreage (Corps 2006a). Not including the fish ladder itself, slightly less than 1.5 acres of steelhead spawning and rearing habitat would be opened.
2.2.5 Summary of Alternatives Table 2. Comparison of Objectives Met in Relation to Each Alternative.
Alternative Objectives Constraint Reduce future Provide natural downstream Improve aquatic Habitat sediment fish kills and Slope stability passage restoration transport habitat degradation No Project No No No No No change 2.0 acres of Yes. Equivalent restored riparian to natural up- Requires Eliminates threat habitat and 1.7 Small Notch and Yes reinforcement of sediment spill miles of restored downstream measures creek in historic conditions channel 2.2 acres of Yes. Equivalent restored riparian Requires highest level to natural up- Eliminates threat habitat and 1.7 Full Removal Yes of reinforcement and downstream of sediment spill miles of restored measures conditions creek in historic channel
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Alternative Objectives Constraint Reduce future Provide natural downstream Improve aquatic Habitat sediment fish kills and Slope stability passage restoration transport habitat degradation Yes. Corps estimates 65- 95% adult 2 acres of restored steelhead riparian habitat passage when Limited, and 1.9 miles of sufficient flow is dependent on Eliminates threat reconstructed Fish Ladder No change present. Would regular of sediment spill channel 10-12 feet continue to be a maintenance above original barrier for channel upstream smaller fish and of dam other aquatic organisms
2.3 Elements Included in All Action Alternatives Implementation of all of the action alternatives would include similar elements to address habitat restoration, stabilization of Spring Mountain Road, measures to protect species of concern, a dewatering plan, planning for construction access, and sediment reuse or disposal. Each is described in detail below:
2.3.1 Habitat Restoration After sediment removal, the exposed areas of the reservoir bed would be restored to natural channel morphology. Depending on what is found underneath the sediment, it may or may not be possible to restore the original channel of York Creek. If restoration of the original channel is not possible, restoration would mimic natural stream configuration upstream of the site. Use of riprap will be limited to areas where rock is essential for bank stability. Disturbed areas will be revegetated with a palette of native multistory plants. A diversity of habitats for aquatic, riparian, and terrestrial species will be created.
For all of the action alternatives, revegetation of the areas disturbed by construction would follow three vegetation types: bank zone, terrace zone, and riparian influenced slope. These zones were based on preliminary hydraulic modeling and will be refined during the detailed design of the recommended alternative (Corps 2006a). Appendix G in the Corps Draft Project Report (Corps 2006a) defines the bank zone as the annually flooded area from 1 to 5 feet below the low flow water surface elevation, the terrace zone as the periodically flooded area 3 to 5 feet above the low flow water surface elevation, and the riparian influenced slope as the rarely or never flooded area above the terrace zone. Plants in the bank zone will include rush, sedge, wildrye, deergrass, willow and alder. The flood-prone terrace zone would be planted with species such as deergrass, wildrye, maple, elder, dogwood, buckeye, oak and fir. Riparian influenced slope plants would include dogwood, redwood, firs, snowberry, oaks, rose, and buckeye. (Corps 2006a)
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2.3.2 Stabilization of Spring Mountain Road Maintaining the stability of the adjoining Spring Mountain Road is considered a project constraint that must be addressed adequately to achieve project success (Corps 2006a). The area is on a sheared shale/serpentinite base, which is somewhat prone to earth movement (Appendix C to Corps 2006a). The dam and spillway may be providing lateral stability for a landslide immediately across the road from the dam embankment. The Fish Ladder Alternative would have the least impact to the stability provided by the dam and spillway. Both the Small Notch and Full Removal Alternatives include slope reinforcement measures as described above.
2.3.3 Species of Concern Steelhead are present below the upper reservoir site, and there is a remote possibility that California red-legged frog (Rana aurora draytonii; CRLF) are present at the lower reservoir (Section 3.3, Biological Resources). Both species are federally listed as threatened. Immediately prior to construction, a qualified biologist will make additional surveys for special-status species. After consultation with and approval from ecological regulators (NOAA Fisheries Service, USFWS, and CDFG), appropriate precautions will be taken to prevent construction impacts to any special-status species found.
2.3.4 Dewatering York Creek is a perennial stream. In order to protect aquatic species and water quality during construction, stream flow will be routed around the construction zone, and the site will be dewatered. A site-specific species protection plan will be developed by a qualified biologist and approved by ecological regulators prior to construction (Section 3.3, Biological Resources). A qualified biologist with appropriate permits from ecological regulators will monitor the dewatering process and subsequent construction activity.
2.3.5 Construction Access Access to the upper reservoir is directly off Spring Mountain Road. The configuration of the reservoir in relation to the road makes construction of a temporary access ramp necessary. Traffic controls will be required when trucks enter and leave the construction area (Section 3.10, Transportation and Traffic).
2.3.6 Sediment Reuse/Disposal Sediment removed from the dam will be placed at one or more locations in or near the City of St. Helena. The material will be placed in some combination at Spring Mountain Vineyard, the Lower York Creek Reservoir, and Clover Flat landfill. The City will determine the reuse and/or disposition of materials removed from the dam and reservoir according to the project alternative selected and, therefore, the amount of material to be placed.
At Spring Mountain Vineyard, reservoir material would be placed as fill and graded as part of an existing project involving reuse of maintenance sediments for vineyard improvement. It is estimated that the vineyard could accommodate approximately 10,000 cubic yards of additional material The project has already been approved by Napa County for a grading permit, which included review of slope stability and erosion control issues, and by ecological regulators from CDFG, RWQCB, and the Corps Regulatory Branch.
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The current storage capacity of the lower reservoir is approximately 156 acre-feet, or 251,000 cubic yards. Under the plan proposed by the Corps, the water level of the lower reservoir would be temporarily lowered, and materials from the upper dam and reservoir would be placed along the edge or bottom. The water would be allowed to return to its regular levels the following winter. It is estimated that under the Small Notch or the Full Dam Removal Alternatives up to approximately 23,000 cubic yards of material might be placed in the lower reservoir. Appendix 2, Lower York Creek Reservoir Revegetation and Mitigation Plan contains specifics on wetland restoration and success standards. Should Clover Flat landfill be needed for additional sediment disposal, the requirements of the landfill’s existing permits will govern sediment placement.
Table 3. Estimated Materials Placement Quantities for Action Alternatives.
Location Small Notch Full Removal Fish Ladder SMV 10,000 cy 10,000 cy 10,00 cy LYCR 23,000 cy 23,000 cy 5,000 cy On-site restoration 4,000 cy 4,000 cy 4,000 cy Clover Flat 3,000 cy 8,000 cy N/A Total 40,000 cy 45,000 cy 19,000 cy
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Figure 3. Plan View of Small Notch.
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Figure 4. Plan View of Full Dam Removal.
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Figure 5. Plan View of Fish Ladder.
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3 Environmental Setting and Consequences of Project Alternatives
3.1 Aesthetics 3.1.1 Setting Upper York Creek Dam and Reservoir are adjacent to Spring Mountain Road, which connects St. Helena with Santa Rosa in Sonoma County. It is a beautiful, twisting, 2-lane road that traverses a narrow canyon through riparian and oak forests, vineyards, and scattered grasslands that is designated as a Napa County scenic roadway (Jones & Stokes and EDAW 2005). In addition to commuter traffic, Spring Mountain Road is used by tourists visiting numerous local wineries.
Once Spring Mountain Road leaves the vicinity of downtown St. Helena, there is little visible development. The character of the area surrounding the project sites at both the upper and lower reservoirs is riparian forest running along the road. The City of St. Helena General Plan calls for preserving and enhancing riparian corridors such as this, partly for their aesthetic values.
Currently, York Creek is compromised by the presence of the Upper York Creek Dam and Reservoir. Approximately 2 acres of aquatic and riparian habitat above the Upper St. Helena Dam have been destroyed due to the dam and sediment accumulation. The riparian areas upstream and downstream are lush, while riparian habitat in the project area is sparse and limited (Corps 2006b).
Potential sediment reuse or placement sites include Lower York Creek Reservoir, a nearby fallow vineyard, and Clover Flat landfill. The lower reservoir is not visible from Spring Mountain Road or from any public spot; however, there is a private residence with a gazebo that overlooks the reservoir, and other private residences may have views of the lower reservoir. The portion of Spring Mountain Vineyard being amended with materials from the upper reservoir is not visible from a public road, and the site will be replanted in accordance with an existing vineyard management plan. Changes in aesthetic conditions at the landfill are not anticipated.
3.1.2 Standards Visual effects are considered significant if the project would have a substantial, permanent, adverse impact on the scenic or visual character of the project area and surrounding environment. (DWR 2004)
3.1.3 No Project Alternative: Impacts and Mitigation Measures Description Under the No Project Alternative, the dam would remain unaltered, and no habitat restoration would occur. Accumulated sediments would be removed as needed to maintain the storage capacity of the reservoir and to prevent potentially damaging sediment releases. On-going maintenance would be required as sediment continues to be deposited each year.
Impact AES-NP1: Aesthetic impacts may occur during maintenance activities at the upper and lower reservoirs through removal of vegetation and use of heavy equipment. (Potentially significant and short-term)
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Removal of riparian vegetation within the reservoir and disturbance from movement of reservoir materials by heavy equipment would occur during maintenance activities. Vegetation will re-establish itself naturally in the reservoir, so long-term impacts would vary depending on the frequency of maintenance required. Erosion control through revegetation with native species in disturbed areas would result in improved aesthetic values following maintenance.
Mitigation AES-NP1: Aesthetic impacts from maintenance would be avoided or mitigated by: • Avoidance of impacts to established vegetation along Spring Mountain Road through establishment of a buffer by a qualified biologist. • Use of Best Management Practices (BMPs) to prevent “track-out” of material from the construction area to the paved public road including: o Equipment must be washed down before moving from the property onto a paved public road. o Visible track-out on the paved public road must be cleaned using wet sweeping or a HEPA filter equipped vacuum device within 24 hours. • Revegetation with native species in disturbed areas to provide erosion control and aesthetically-pleasing wildlife habitat. • Avoidance of impacts from glare and/or light by working during daylight hours only.
Significance after Mitigation. Less than significant; beneficial in the long term.
Impact AES-NP2: Placement of materials removed from the upper reservoir during project activities may result in aesthetic impacts at the lower reservoir. (Potentially significant and short-term)
Should placement of excavated sediment occur at Lower York Creek Reservoir, the water level would need to be lowered, resulting in a temporary aesthetic impact because the banks of the reservoir and the placed sediment may be visible from nearby residences. This impact would be less than significant in the short term and beneficial in the long term with implementation of mitigation as described below.
Mitigation AES-NP2: If sediment is placed at the Lower York Creek Reservoir that would be visible from nearby private residences, the City of St. Helena will minimize any visual impacts by: • Limiting disturbance to existing vegetation and revegetating with native species that will cover the surface of the sediment and blend in with existing vegetation. • Having all work conducted under the supervision of a licensed and/or certified professional with experience in native revegetation, wildlife habitat restoration, and erosion control. • Following all additional revegetation requirements in Appendix 2: Lower York Creek Reservoir Revegetation and Mitigation Plan.
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Success Criteria AES-NP2: Wetland plantings would be considered successful if cover at the end of one year is equal to 70% of the cover of nearby equivalent reference wetlands. • If after one year 70% percent cover is not present, a certified professional will determine if additional planting is required or if an additional growing season for existing plants will allow growth to meet the cover criterion. • If after two years this criterion is not met, additional plantings will be required until the area has 70% of the reference cover established for one year or more.
Upland plantings would be considered successful if 80% of the woody plants installed are alive and healthy and have been in the ground for three years. • Replacement planting shall be required until this success criteria is met.
Significance after Mitigation: Less than significant; beneficial in the long term.
Impact AES-NP3: Temporary aesthetic impacts from transportation of excavated materials would occur during project activities. (Less than significant and short-term)
The riparian corridor and forested sections of Spring Mountain Road are approximately 6.2 miles long. The section visually affected by the project’s construction activities is 0.3 miles, or less than 5% of the road; therefore, the project would not substantially affect the visual character of the site and surroundings. (See also, discussion in Section 3.10, Traffic and Transportation.) Construction would be performed during daylight only to avoid impacts from light or glare.
Mitigation AES-NP3: No mitigation will be necessary because the impact will be less than significant.
Impact AES-NP4: Placement of materials along the shore of the lower reservoir may result in impacts to views of the water surface area. (Potentially significant, long-term, and unavoidable)
Placement of materials along the shore of the lower reservoir may have a significant impact due to changes in water surface area as viewed from residences above. It is estimated that the total potential reduction of the lower reservoir’s water surface area is between 2% and 6%. Although revegetation with native riparian and wetland species will occur as described in Appendix 2: Lower York Creek Reservoir Revegetation and Mitigation Plan, individual neighbors may experience a change in vista.
Significance after Mitigation. Potentially significant and unavoidable.
3.1.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description As with the No Project Alternative, the Small Notch Alternative may result in temporary aesthetic impacts through removal of vegetation and construction activities involving use of heavy equipment at the upper and lower reservoirs, placement of materials at the lower reservoir, and transportation of excavated materials. When mitigated, these impacts are short-
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term and less than significant. Placement of fill along the shore may alter the amount of water surface as viewed from residences above the project site, a potentially significant, long-term, and unavoidable impact. Plantings, as detailed in Appendix 2: Lower York Creek Reservoir Revegetation and Mitigation Plan, will be utilized to mitigate the visual impacts, and installation of this alternative will result in long-term aesthetic benefits. Full discussion of these impacts, mitigation measures, and success criteria for plantings is found in AES-NP1, AES-NP2, AES- NP3, and AES-NP4 above.
3.1.5 Full Dam Removal: Impacts and Mitigation Measures Description The Full Dam Removal Alternative generates the largest quantity of sediment and dam materials of all the alternatives (Corps 2006a). Aesthetic impacts, mitigation measures, and success criteria from the Full Dam Removal Alternative would be the same as those described for the No Project and Small Notch Alternatives. Discussion of impacts, mitigation, and success criteria is found in AES-NP1, AES-NP2, AES-NP3, and AES-NP4.
3.1.6 Fish Ladder: Impacts and Mitigation Measures Description Aesthetic impacts, mitigation measures, and success criteria from the Fish Ladder Alternative would be the same as those described for the No Project and Small Notch Alternatives. Although the Fish Ladder Alternative generates the least amount of sediment and dam materials of all the action alternatives, changes in water surface area may be potentially significant to neighbors. Discussion of impacts, mitigation, and success criteria is found in AES- NP1, AES-NP2, AES-NP3, and AES-NP4.
3.1.7 Section References California Office of Planning and Research. 2006. State Clearinghouse (SCH) CEQAnet Database. Accessed at: http://www.ceqanet.ca.gov/.
Department of Water Resources (DWR). 2004. Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project. January 14, 2004.
Jones & Stokes and EDAW, Inc. 2005. Napa County Baseline Data Report, Version 1 – November 30, 2005. Prepared for the Napa County Conservation, Development and Planning Department. November 2005. Available for viewing on the Napa County website. Accessed at: http://www.co.napa.ca.us/gov/departments/29000/bdr/index.html
Prunuske Chatham, Inc. (PCI) 2007b. Lower York Creek Dam Revegetation and Mitigation Plan. January 2007. Appendix 2
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California (DPR). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
U.S. Army Corps of Engineers (Corps). 2006b. Draft Environmental Assessment: Upper York Creek Ecosystem Restoration Project, Napa County, California (EA). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006.
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3.2 Air Quality 3.2.1 Setting The Napa Valley is a long, north-south valley largely surrounded by mountains except at the southern end where the Napa River drains into San Pablo Bay. Wind direction in the area is controlled by topography, climate, and the proximity of San Francisco Bay. During the summer and early fall, when work will occur, warm inland temperatures cause the air to rise, pulling cool air off the Pacific Ocean through the Golden Gate. This process often results in high winds on San Francisco Bay. The same process happens in microcosm at the south end of the Napa Valley. Heating on the valley floor draws air in from the main body of San Francisco Bay, across San Pablo Bay, and up the valley. Winds in the area are much gentler, however, with almost 50% of the winds below 4 mph. On summer evenings, the wind often reverses direction. (Jones & Stokes and EDAW, Inc. 2005)
York Creek runs through a narrow canyon on the west side of the Napa Valley. During summer days, the combination of valley floor heat and prevailing wind direction causes air to flow westerly up the York Creek valley. This will generally mean that airflow is from the project site uphill toward less densely populated sites. Identified possible reuse or disposal sites are within the same creek valley or on the valley floor north of the City, which again will tend to mean that airflow is away from the densely populated areas.
Regulatory Setting Air quality and emissions are regulated by the California Air Resources Board (CARB), which is a part of the California Environmental Protection Agency (CalEPA). Under CARB, the state is divided into 15 local air districts that have primary responsibility for controlling air pollution from stationary sources. The project will take place within the jurisdiction of the Bay Area Air Quality Management District (BAAQMD). The District's jurisdiction encompasses all of seven counties (Alameda, Contra Costa, Marin, San Francisco, San Mateo, Santa Clara, and Napa) and portions of two others (southwestern Solano and southern Sonoma). Each a district must assess air quality for 6 criteria pollutants: ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, coarse particulate matter (particulate matter smaller than 10 microns (PM10)), and particulate matter smaller than 2.5 microns (PM2.5).
Asbestos The Upper St. Helena Dam was constructed in 1900 using on-site materials from the creation of the reservoir (Corps EA 2006). Construction materials used to build the dam are believed to include native serpentine soils containing chrysotile asbestos. Asbestos is a group of six different fibrous minerals found in nature (ATSDR 2001). Serpentine soils are endemic and unique to the western states. Serpentine is the state rock of California and relatively common in pockets throughout the Bay Area. Geologists have observed serpentine in outcroppings along Spring Mountain Road and in York Creek (ITSI 2003). The fibers may be released when areas containing asbestos are disturbed. Asbestos might be found in the dust resulting from removal of dam material.
The Corps retained the services of Innovative Technical Solutions, Inc. (ITSI) to analyze material in the dam and reservoir. Two borings were installed in the dam at multiple depths in
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September 2003. Borings are drilled samples of earth collected to view analyze the soil while preserving the strata or layers of soil as they exist below the surface.
Chrysotile asbestos was found in one boring at a concentration of 2.8% at a depth of 35 feet and at 3.5% at a depth of 15 feet. A second boring site found no detectable levels of asbestos. The asbestos found in the boring is attributed to the material used to construct the dam and not from any other source. The two soil boring sites on the dam were located at opposite ends of the dam. One site was about midway from the spillway to the crest of the dam, which is where the asbestos was found. The second location is approximately midway between the crest and the hillside. This sampling location found no detectable levels of asbestos in the borings. It was found only in trace amounts elsewhere in the reservoir.
Dam material will be re-used only where it can be capped (buried under clean fill) to prevent releases into the air from erosion. Due to the low levels of naturally-occurring asbestos at the project site, it is unlikely that asbestos will pose a problem for nearby residents. Asbestos risk will be greatest for construction site workers (see Section 3.7, Hazardous Materials, for additional information associated with health risks). Best management practices (BMPs) will be used to limit dust at the project sites and in transportation to and from the sites to ensure proper safety measures are used. An Asbestos Dust Mitigation Plan Application from the BAAQMD will be approved prior to construction for asbestos containment. The plan contains additional measures for BMPs relating to safe practices for work involving asbestos.
Hydrogen Sulfide Hydrogen sulfide gas may pose a threat to air quality if it is released during movement of sediment in the reservoir. Sediment collected in stagnant, moist areas often contains hydrogen sulfide gas that forms during the decomposition of organic matter in anaerobic conditions. The gas smells like rotten eggs and occurs naturally. Quantities of hydrogen sulfide in the sediments in the reservoir are unknown until the construction work begins. Maintenance work at the site has not created an air quality problem in the past.
Hydrogen sulfide breaks down into elemental sulfur as evidenced by yellowish soils in the reservoir. Hydrogen sulfide can be problematic if inhaled in large quantities (see Section 3.7, Hazardous Materials, for additional information associated with health risks). Low-lying areas with poor ventilation are of special concern as hydrogen sulfide tends to build up in these areas. Hydrogen sulfide may be an issue for the construction workers in the immediate area. On-site staff will wear hydrogen sulfide meters to detect levels of hydrogen sulfide in the air. These personal sensors sound an alarm if the levels become dangerous. Elsewhere in the valley, natural airflow should be sufficient to disperse hydrogen sulfide. If levels are detected above BAAQMD’s maximum levels, work will be stopped immediately until a remedy can be found.
PM10 The federal EPA has set air quality standards for PM10, which are regulated by BAAQMD in the Bay Area. For each pollutant, the region is designated as being in attainment (below the regulatory limit) or non-attainment for both state and federal standards. Attainment standards can be used to assess the air quality of sub-basins like the Napa Valley. Particulate matter may consist of small liquid or solid particles including: exhaust from motor vehicles, wood burning stoves or wildfires, dust, or industrial discharges (EPA 2006c). PM10 measures small particles in microns or micrometers, equivalent to one millionth of a meter. For reference, the average
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human hair is approximately 60 microns, or 6 times the size of the PM10 and 24 times larger than PM2.5 (CARB 2005). PM10 can cause respiratory and other health issues. (See Section 3.7, Hazardous Materials, for additional health information.)
Image taken from the CARB website (CARB 2005).
Table 4 below shows the status of the greater project area. In 2004, the most recent year for which full data is available, Napa County met air quality standards in every area except coarse particulates (PM10).
Table 4. Air Quality in the San Francisco Bay Area and Napa County
Carbon Nitrogen Sulfur Ozone PM10 PM2.5 monoxide dioxide Dioxide (pphm) (µg/m3) (µg/m3) (ppm) (pphm) (ppb) 1 hr 8 hr 1 hr 8 hr 1 hr Ann 24 hr Ann 24 hr Ann 24 hr Ann National Attainment --- 8 35 9 ---- 5.3 140 30 150 50 65 15 Standard California Attainment 9 --- 20 9 25 --- 40 --- 50 20 --- 12 Standard Bay Area Nat --- N A A --- A A --- A U A A Attainment Cal N A A A A --- A A N N --- N Status (2004) Napa County Annual 9 7 3.7 2.0 6 1.1 ------60 20.7 ------Average (2004) Napa County Attainment Nat --- A A A --- A ------A A ------Status Cal A --- A A A ------N N ------A = attainment of an established air quality standard N = non-attainment (BAAQMD 2007a, 2007c)
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Emissions from the various project alternatives have been identified and estimated in the table below. Figures were computed using information from the Western Regional Air Partnership and the BAAQMD CEQA Guidelines.
Table 5. Upper St. Helena Dam, Expected Project Emissions Action Alternatives Preferred, Small Full Removal Fish Ladder Notch Alternative Alternative Alternative Amount of material to be moved 39244 45409 19772
Amount to be moved off-site 38904 45057 19367 Months of construction (22 business 10 12 10 days each) Tons PM10 emitted as fugitive dust 8.91 10.33 4.61
PM10 lbs/day 80.99 78.25 41.95
PM10 kg/project from construction 86.34 99.90 43.50 equipment (BAAQMD est)
Carbon monoxide in kg from 5415.67 6266.44 2728.54 construction equipment (BAAQMD est) Nitrogen oxide in kg from construction 1663.95 1925.34 838.33 equipment (BAAQMD est) Sulfur dioxide in kg from construction 180.52 208.88 90.95 equipment (BAAQMD est)
Tons PM2.5 emitted (total) 0.89 1.03 0.46 PM10 emissions with control factors 1.16 1.34 0.60 (apply water at intervals 70% reduction, limit vehicle speed to 15 mph 57% reduction - total reduction 70% + 57% of remaining 30% = 87%) Controlled PM10 lbs/day 10.53 10.17 5.45 Controlled tons PM2.5 (total) 0.12 0.13 0.06
3.2.2 Standards BAAQMD presumes asbestos is present in serpentine soils unless proven otherwise, and work in these areas is a significant impact requiring mitigation practices during construction (BAAQMD 1999). The Asbestos Dust Mitigation Plan Application contains additional measures for BMPs relating to safe practices for work involving asbestos. Section 3.7, Hazardous Materials, contains additional information on asbestos as it relates to human health.
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Hydrogen sulfide BAAQMD regulation 9-2-301 states that in one 24-hour period, a person shall not emit hydrogen sulfide quantities resulting in ground level concentrations in excess of 0.06 parts per million (ppm) averaged over 3 consecutive minutes or 0.03 ppm averaged over 1 hour (BAAQMD 1999b).
BAAQMD CEQA Guidelines have developed limits for project impacts. Projects would be cumulatively significant if they: • Produce carbon monoxide (CO) concentrations above state or national standards. These must be estimated for projects with vehicle emissions of CO exceeding 550 lbs/day; if project traffic would cause a decline on a road operating at a Level of Service (LOS) of D, E, or F, or if traffic would cause LOS to decline to D, E, or F; or if project traffic would increase traffic volume by 10% or more. • Produce PM10 emissions above 80 pounds per day or 15 tons per year. • Have potential odor, toxics, or accidental release impacts.
3.2.3 No Project Alternative: Impacts and Mitigation Measures Description Annual maintenance activities at the reservoir are required if the dam remains to ensure the safety of the structure, residents, and aquatic life. Maintenance would involve removing accumulated sediment from the reservoir and transporting it to another location. Construction activities would generate emissions from construction equipment and dust.
The air pollutant of greatest concern from maintenance activities is particulate matter, specifically particulates between 2.5 and 10 microns known as PM10. Construction site sources for PM10 on this project include dust from grading, excavation and other earth moving activities, and emissions from construction equipment. Based on PM10 emissions calculations for the action alternatives (Table 5), it appears that maintenance activities would not create a significant impact to air quality. Construction BMPs such as wetting soils and covering loads in the trucks would be used to limit dust at the construction site and in transporting materials off site.
Impact AIR – NP1: Asbestos dust could be released into the air during project activities. (Potentially significant and short-term)
Mitigation AIR – NP1: In order to avoid or minimize air quality impacts from maintenance, the following would occur: • Prior to any project maintenance activity, a Storm Water Pollution Prevention Plan (SWPPP) would be prepared to determine BMPs to avoid potential adverse impacts from construction activities, including those related to air quality. • The sediments in the reservoir shall be tested prior to any movement or removal. • The BAAQMD protocol for asbestos management shall be followed. An Asbestos Dust Mitigation Plan must be applied for and approved prior to maintenance activities if the disturbed area is greater than one acre.
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• If required, an air quality permit would be obtained from BAAQMD for work involving the naturally-occurring asbestos. • If the maintenance area is less than one acre, the following requirements from BAAQMD must be followed (BAAQMD CCR Title 17, Section 93105): o Construction vehicle speed at the work site must be limited to fifteen (15) miles per hour or less. o Prior to any ground disturbance, sufficient water must be applied to the area to be disturbed to prevent visible emissions from crossing the property line. o Areas to be graded or excavated must be kept adequately wetted to prevent visible emissions from crossing the property line. o Storage piles must be kept adequately wetted, treated with a chemical dust suppressant, or covered when material is not being added to or removed from the pile. o Equipment must be washed down before moving from the property onto a paved public road. o Visible track-out on the paved public road must be cleaned using wet sweeping or a HEPA filter equipped vacuum device within 24 hours.
Significance after Mitigation: Less than significant.
Impact AIR – NP2: Hydrogen sulfide gas may pose a threat to air quality if it is released during movement of sediment in the reservoir. (Potentially significant and short-term) Sediment collected in stagnant, moist areas often contains hydrogen sulfide gas that forms during the decomposition of organic matter in anaerobic conditions. However, it is unlikely that hydrogen sulfide levels would pose a threat to public safety given the open area and low density of people and housing in the vicinity. Hydrogen sulfide dissipates quickly in the air and would likely pose the greatest threat to construction workers. Construction workers on site shall be protected from hydrogen sulfide risk. (See Section 3.7, Hazardous Materials, for additional hydrogen sulfide safety measures.)
Mitigation AIR – NP2: Construction workers would be equipped with personal hydrogen sulfide monitoring devices. OSHA protocols would be followed for the safety of construction workers. If hydrogen sulfide levels exceed safe levels, work would be halted until the hydrogen sulfide dissipates.
Significance after Mitigation: Less than significant.
Impact AIR – NP3: Project activities could result in an increase PM10 emissions during sediment removal. (Potentially significant and short-term) PM10 emissions would occur from heavy equipment operations, including earthmoving and material sorting for transport off site. Maintenance activities would occur during the low water
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season, likely late summer and/or early fall. Off-site locations would need to be determined as needed. Construction related PM10s would affect the off-site locations. Based on Table 5 above, the PM10 levels after mitigation would be ±5-10 lbs/day for each of the alternatives. There would not be a significant effect from coarse particulate emissions. Emissions levels from the various alternatives, including the No Project Alternative, would be far less than cumulatively significant as determined by the BAAQMD.
Mitigation AIR – NP3: PM10 emissions released during maintenance activities at the Upper St. Helena Dam and various sediment delivery sites could be reduced with the proper BMPs in place. The City of St. Helena shall implement the following measures from BAAQMD to limit PM10 emissions: • BAAQMD CEQA Guidelines for PM10 emission BMPs for construction shall be included in the SWPPP. • Water all active construction areas at least twice daily. • Cover all trucks hauling soil, sand, and other loose materials or require all trucks to maintain at least two feet of freeboard. • Pave, apply water three times daily, or apply (non-toxic) soil stabilizers on all unpaved access roads, parking areas and staging areas at construction sites. • Sweep daily (with water sweepers) all paved access roads, parking areas and staging areas at construction sites. • Sweep streets daily (with water sweepers) if visible soil material is carried onto adjacent public streets.
Significance after Mitigation. Less than significant.
3.2.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures, Description Implementation of all the action alternatives, including the Small Notch Alternative, may result in potential impacts from asbestos dust, hydrogen sulfide, and PM10 emissions as discussed in the No Project Alternative (AIR-NP1, AIR-NP2, and AIR-NP3), except that impacts from all of the action alternatives would be reduced because no follow-up sediment removal would be necessary. Mitigation measures described in the No Project Alternative would be implemented to reduce impacts to a less than significant level (Mitigations AIR-NP1, AIR-NP2, and AIR-NP3).
When material from the dam is removed to create the notch, it is possible that serpentine rocks would be broken open and serpentine soils exposed to the air and dried. Both of these can release friable chrysotile asbestos into the atmosphere. This additional potential impact and mitigation are described below. As discussed above in Mitigation AIR-NP1, prior to project construction, a SWPPP would be prepared to determine BMPs to limit negative impacts caused by construction activities, including those related to air quality. BAAQMD CEQA Guidelines contain additional PM10 emission BMPs for construction that should be applied to the SWPPP. An air quality permit would be obtained from the BAAQMD for the naturally-occurring asbestos.
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Impact AIR – PA1: Asbestos dust could be released into the air during removal of sediment and/or dam materials at the upper reservoir and during placement at reuse/disposition sites. (Potentially significant and short-term) Naturally-occurring asbestos is present in the earthen upper dam, which was constructed using local serpentine soils that contain low levels of asbestos. Removal of the dam may release asbestos into the air. An air quality permit (BAAQMD 2007b) will be obtained from the BAAQMD for work involving the naturally-occurring asbestos.
Mitigation AIR PA1: Project work will use BMPs to avoid releasing dust from construction activities at the project sites and along public and private roads. Dam material will be used as fill only in locations where it can be capped with clean fill to limit the release of asbestos into the environment. These actions will minimize airborne asbestos to limit the cumulative impacts from the project.
The City of St. Helena shall implement the following measures revised to fit this project from the BAAQMD Asbestos Dust Mitigation Plan Application to limit asbestos dust from becoming airborne: • Prevent track-out of material from the construction area to the paved public road. Any visible track-out on the public road at all project sites must be removed using wet sweeping or a HEPA filter-equipped vacuum device at the end of the work day or at least once a day. In addition, one of the following shall be installed. o A gravel pad using good engineering practices to clean the tires of exiting vehicles. o A tire shaker. o A wheel wash system. o Pavement extending for not less than 50 consecutive feet from the intersection with the paved public road. • Active storage piles must be adequately wet or covered with tarps. • Inactive storage areas and storage piles (more than 7 days) shall incorporate one or more of the following items: o Keep the surface adequately wet. o Establish and maintain surface crusting sufficient to satisfy the test in subsection 93105(h)(6). o Cover with tarps or vegetative cover. o Install wind barriers of 50% porosity around three sides of a storage pile. o Install wind barriers across open areas. • Traffic along on-site unpaved roads, parking lots, and staging areas must not exceed a vehicle speed of 15 miles per hour. In addition, one of the following measures must be utilized. o Water every two hours during active operations or sufficiently often to keep the area adequately wetted. o Install wind barriers of 50% porosity around three sides of a storage pile.
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o Maintain a gravel cover with a silt content that is less than 5% and asbestos content that is less than 0.25%, as determined using an approved asbestos bulk test method, to a depth of 3 inches on the surface being used for travel. • Earth moving activities must include one of the following: o Pre-wet the ground to the depth of anticipated cuts. o Suspend grading operations when wind speeds are high enough to result in dust emissions crossing the property line, despite the application of dust mitigation measures. o Apply water prior to any land clearing. • Off-site transport cannot occur unless trucks are maintained to ensure no spillage can occur from holes or other openings in cargo compartments and the loads are adequately wet. In addition, the load must either be covered with tarps or loaded so that material (including non-hazardous manifests) do not touch the front, back, or sides of the cargo compartment at any point less than 6 inches from the top and that no point of the load extends above the top of the cargo compartment. • Upon completion of the project, disturbed surfaces shall be stabilized using one or more of the following: o Establish a vegetative cover. o Place at least 3 inches of non asbestos-containing material.
Before construction, in accordance with the naturally-occurring asbestos ATCM (CCR Title 17, §93015), the City shall get an Asbestos Dust Mitigation Plan Application approved for specific measures that will effectively control dust for the particular project and site.
Materials placed off site at the lower reservoir will be secured in place with both 3 inches of nonasbestos-containing soil and vegetative planting above the expected average water level of the reservoir (Appendix 2 for planting plan). Dam material will not be transported to Spring Mountain Vineyard or Clover Flat landfill.
Significance after Mitigation. Less than significant.
3.2.5 Full Dam Removal: Impacts and Mitigation Measures Description Like the other action alternatives, full removal has the potential to release asbestos dust from removal of sediment and dam materials, from hydrogen sulfide trapped in the sediment, and from PM10 emissions into the air. See discussion in the No Project and Preferred Alternative sections (Mitigations AIR-NP1, AIR-NP2, AIR-NP3, and AIR-PA1). As discussed above in Mitigation AIR-NP1, prior to project construction, a SWPPP will be prepared to determine BMPs to limit negative impacts caused by construction activities, including those related to air quality. The BAAQMD CEQA Guidelines have additional PM10 emission BMPs for construction that should be applied to the SWPPP. An air quality permit will be obtained from the BAAQMD for the naturally-occurring asbestos.
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3.2.6 Fish Ladder: Impacts and Mitigation Measures Description The fish ladder would require on-going maintenance to prevent it from becoming clogged with sediment. The maintenance requirements would be similar to the No Project Alterative above, although the ladder itself would also require sediment and debris removal to maintain fish passage. Like the other action alternatives, the Fish Ladder Alternative has the potential to release asbestos dust from removal of sediment and dam materials, from hydrogen sulfide trapped in the sediment, and from PM10 emissions into the air. See discussion in the No Project and Preferred Alternative sections (Mitigations AIR-NP1, AIR-NP2, AIR-NP3, and AIR-PA1) regarding sediment removal, sorting, replacement, construction activities, and the SWPPP and BAAQMD CEQA guidelines.
3.2.7 Section References Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service. 2001. Toxicological Profile for Asbestos.
Bay Area Air Quality Management District (BAAQMD). 1999a. BAAQMD CEQA Guidelines: Assessing the Air Quality Impacts of Projects and Plans. Prepared by the Planning and Research Division of the Bay Area Air Quality Management District. December 1999.
Bay Area Air Quality Management District (BAAQMD). 1999b. BAAQMD Rule 9-2 Inorganic Gaseous Pollutants, Hydrogen Sulfide. Amended October 6, 1999.
Bay Area Air Quality Management District (BAAQMD). 2007a. Ambient Air Quality Standards and Bay Area Attainment Status. Accessed at: http://www.baaqmd.gov/pln/air_quality/ambient_air_quality.htm
Bay Area Air Quality Management District (BAAQMD). 2007b. Asbestos Airborne Toxic Control Measure for Construction and Grading Operations. Asbestos Dust Mitigation Plan Application.
Bay Area Air Quality Management District (BAAQMD). 2007c. Emission Inventory. Accessed at: http://www.baaqmd.gov/pln/emission_inventoryYear2003BY00.htm
California Air Resources Board (CARB). 2005. Ambient Air Quality Standards for Particulate Matter. Accessed at: http://www.arb.ca.gov/research/aaqs/pm/pm.htm
Innovative Technical Solutions, Inc. (ITSI) 2003. Final Report HTW Assessment Upper York Creek Ecosystem Restoration Project St. Helena, California. Prepared for U.S. Army Corps of Engineers San Francisco District. December 2003.
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California (DPR). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
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U.S. Army Corps of Engineers (Corps). 2006b. Draft Environmental Assessment: Upper York Creek Ecosystem Restoration Project, Napa County, California (EA). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006.
U.S. Environmental Protection Agency (EPA). 2006c. Particulate Matter. Accessed at: http://www.epa.gov/reg5oair/naaqs/pm.htm
Western Regional Air Partnership. 2004. Fugitive Dust Handbook. Accessed at: http://www.wrapair.org/forums/dejf/fdh/ch3-cons dem.html
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3.3 Biological Resources 3.3.1 Setting This section describes the existing biological resources at the Upper York Creek Ecosystem Restoration Project sites, identifies the potential impacts of the proposed project on those resources, and discusses mitigation measures to eliminate or minimize potentially significant impacts imposed by the project. For the purposes of this study, the project area includes three project sites: Upper York Creek Dam and Reservoir (UYCD), Lower York Creek Reservoir (LYCR), and Spring Mountain Vineyard (SMV), including all access routes and staging areas.
The UYCD is located immediately adjacent to Spring Mountain Road. It is comprised of an earthen dam structure and a reservoir behind the dam that is full of sediment. LYCR is an off- stream impoundment located downhill of the upper reservoir on the east side of Spring Mountain Road. SMV is a fallow field upslope and adjacent to the upper reservoir. Biological resources at two additional reuse sites, Clover Flat landfill and Fulton Lane, were not evaluated as part of the DEIR.
The regional setting is the York Creek watershed, Napa County, California, which is located in the northwest portion of Napa County, approximately 60 miles north of the San Francisco Bay within the California Coast Range on the western side of the Napa River watershed. The York Creek watershed runs approximately 7.24 miles from its headwaters to its confluence with the Napa River and encompasses approximately 4.4 square miles. Biological resources described within the project area are typical of those found within the coast range and adapted to a Mediterranean climate with cool summers (CDFG 2002). The region is primarily characterized by woodland, coniferous forest, and sagebrush shrubland habitats (UCSB 1998).
Potentially occurring special-status animals, plants, and natural communities on the sites were determined from on-site biological surveys and a review of available resources, including the California Department of Fish and Game’s (CDFG) California Natural Diversity Data Base (CNDDB) (CDFG 2006a), California Native Plant Society (CNPS) Inventory of Rare and Endangered Vascular Plants of California on-line inventory (CNPS 2006), U.S. Fish and Wildlife Service (USFWS) online species lists (USFWS 2006), and background literature. The proposed project sites were also examined for the presence of potential jurisdictional wetlands and other waters of the U.S.
Biological surveys were conducted by Prunuske Chatham, Inc., and Coast Range Biological, LLC, on June 19, 2006, and December 22, 2006. A California red-legged frog (Rana aurora draytonii) site assessment and focused daytime survey was conducted on April 13, 2006, at the UYCD and LYCR. Fish surveys at the upper reservoir were conducted on September 14, 18, 19, and 20, 2006. A routine delineation of all potential jurisdictional wetlands and other waters of the U.S. was conducted on December 22, 2006. The delineation will be verified by the U.S. Army Corps of Engineers (Corps). Spring botanical surveys will be completed at the UYCD and LYCR in spring 2007.
3.3.1.1 Existing Botanical Resources For the purpose of this DEIR, plant communities and habitat were classified using A Manual of California Vegetation (Sawyer and Keeler-Wolf 1995) and List of California Terrestrial Communities
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Recognized by the Natural Diversity Database (CDFG 2003). Vegetation communities observed on the project area have been grouped into seven broad categories: redwood forest, mixed evergreen forest, riparian woodland, foothill pine-oak woodland, freshwater wetland, non- native grassland, and ruderal.
Botanical surveys concentrated on: (1) locating suitable macro-habitat (i.e., general plant communities) and micro-habitat (i.e., seeps, serpentine substrates) for special-status plants identified during the background literature search; and (2) documenting all plant species on the project area that were identifiable at the time of the field visits. Field visits were made to the project area on June 19 and December 22, 2006. Primary plant communities occurring in the project area were located and mapped. Field visits occurred at a time that would identify summer blooming special-status plant species, but they occurred outside the normal blooming window of most spring blooming plant species. Surveys were conducted on foot, generally following methods outlined in Nelson (1987). All accessible areas within each project site were surveyed. A follow up survey for spring blooming special-status plant species will be conducted in spring 2007.
During the field visits, 126 plant species were observed on the project area. A list of these plant species is included as Table 6.
Upper Reservoir The upper reservoir supports four general plant communities: redwood forest, mixed evergreen forest, riparian woodland, and ruderal (Figure 6). Ruderal habitat occurs in highly disturbed areas and is dominated by non-native grasses and forbs. Land uses surrounding the site include open space and Spring Mountain Road.
Redwood forest, composed of the redwood series7, occurs immediately below the dam and upstream of the reservoir. Redwood (Sequoia sempervirens8) dominates the canopy, with a mixed subcanopy of tanoak (Lithocarpus densiflorus), California bay (Umbellularia californica), and big- leaf maple (Acer macrophyllum), and a generally sparse understory of native herbaceous species including wood fern (Dryopteris arguta), sweet-scented bedstraw (Galium triflorum), sweet cicely (Osmorhiza chilensis), and trailplant (Adenocaulon bicolor), and occasional non-native species including forget-me-not (Myosotis latifolia) and invasive English ivy (Hedera helix).
Mixed evergreen forest, composed primarily of the Douglas-fir series, occurs on well-drained slopes above UYCD. Douglas-fir (Pseudotsuga menziesii var. menziesii) dominates the canopy, with a subcanopy of madrone (Arbutus menziesii), coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and California bay, and a mixed understory of shrubs and herbs including poison oak (Toxicodendron diversilobum), toyon (Heteromeles arbutifolia), coyote brush (Baccharis pilularis), sticky monkeyflower (Mimulus aurantiacus), soap plant (Chlorogalum pomeridianum), snakeroot (Sanicula crassicaulis), and bracken fern (Pteridium aquilinum var. pubescens).
Riparian woodland, composed primarily of the white alder series and mixed willow series, occurs in and adjacent to the York Creek stream channel and reservoir. Dominant species are
7 Vegetation series nomenclature follows Sawyer and Keeler-Wolf (1995). 8 Botanical nomenclature follows Hickman (1993), unless otherwise indicated.
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primarily wetland-classified trees and shrubs, including white alder (Alnus rhombifolia), shining willow (Salix lucida ssp. lasiandra), red willow (S. laevigata), narrow-leaved willow (S. exigua), Oregon ash (Fraxinus latifolia), big-leaf maple, elk clover (Aralia californica), spicebush (Calycanthus occidentalis), California blackberry (Rubus ursinus), and Himalayan blackberry (R. discolor). Scattered herbaceous, wetland-classified species are also present, including horsetail (Equisetum sp.), tall flatsedge (Cyperus eragrostis), narrow-leaved cattail (Typha angustifolia), American brooklime (Veronica americana), water cress (Rorippa nasturtium-aquaticum), and water- parsley (Oenanthe sarmentosa).
Ruderal vegetation, composed of a highly disturbed phase of the California annual grassland series, occurs primarily on the York Creek dam berm and associated disturbed areas adjacent to Spring Mountain Road. Dominant species are non-native grasses and forbs adapted to disturbance, including fennel (Foeniculum vulgare), wild oats (Avena sp.), hedgehog dogtail (Cynosurus echinatus), black mustard (Brassica nigra), Italian ryegrass (Lolium multiflorum), and ripgut brome (Bromus diandrus).
Vegetation community descriptions are based on the June 19, 2006, field visit. After this visit, prior to the December 22, 2006, field visit, routine maintenance was conducted in the upper reservoir by the City of St. Helena to remove accumulated sediment deposited behind the dam. As a result of dredging, most of the opportunistic riparian woodland habitat upstream of the dam within the reservoir was removed. No other vegetation communities were affected.
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Lower Reservoir The primary communities occurring within the LYCR and immediate area are foothill pine-oak woodland, freshwater wetland, non-native grassland, and ruderal (Figure 7). Land uses surrounding the site include open space, residential, roadways, and agriculture (vineyards).
Foothill pine-oak woodland, composed primarily of the foothill pine series and blue oak series, occurs on well-drained uplands surrounding the reservoir. Native trees dominate the canopy, including foothill pine (Pinus sabiniana), blue oak (Quercus douglasii), coast live oak, California black oak, madrone, California buckeye (Aesculus californica), and occasional Douglas-fir and valley oak (Q. lobata). The understory is composed of a mix of shrubs and herbs, including toyon, common manzanita (Arctostaphylos manzanita ssp. manzanita), coyote brush, sticky monkeyflower, poison oak, deer weed (Lotus scoparius), and hairy honeysuckle (Lonicera hispidula var. vacillans).
Freshwater wetland, composed of the bulrush-cattail series, occurs along the reservoir’s fringes. Dominant species are primarily wetland-classified shrubs and herbs, including California bulrush (Scirpus californicus), narrow-leaved cattail, spikerush (Eleocharis macrostachya), iris- leaved rush (Juncus xiphioides), and tall flatsedge, with occasional riparian trees such as Fremont cottonwood (Populus fremontii ssp. fremontii) and narrow-leaved willow.
Non-native grassland, composed of a phase of the California annual grassland series, occurs on berms fringing the lower reservoir and in other well-drained uplands adjacent to foothill pine- oak woodland. Dominant species are a mix of native and non-native grasses and forbs. The natives include clarkia (Clarkia sp.), blue-eyed-grass (Sisyrinchium bellum), harvest brodiaea (Brodiaea elegans), California poppy (Eschscholzia californica), soap plant, and purple needlegrass (Nassella pulchra). The non-natives include wild oats, Italian ryegrass, soft chess (Bromus hordeaceus), hedgehog dogtail, rose clover (Trifolium hirtum), English plantain (Plantago lanceolata), and Italian thistle (Carduus pycnocephalus). Ruderal habitat occurs in highly disturbed areas, such as along roads and staging areas, and is dominated by non-native grasses and forbs characteristic of non-native grassland.
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Spring Mountain Vineyard The SMV site is a fallow, formerly terraced vineyard located at approximately 1,170 feet in elevation. A swale bisects two sloping hillsides into the eastern and western sections. The primary plant communities occurring within the project site and immediate area are non-native grassland and mixed evergreen forest (Figure 8). Land uses surrounding the site include vineyard, winery facilities, and access roads.
Non-native grassland, composed of a highly disturbed phase of the California annual grassland series, is the dominant plant community on the project site and covers terraced hillsides throughout the fallow vineyard. Dominant species are non-native grasses and forbs adapted to disturbance, including ripgut brome, wild oats, hedgehog dogtail, vulpia (Vulpia sp.), geranium (Geranium dissectum), barley (Hordeum murinum), rose clover, common dandelion (Taraxacum officianale), prickly lettuce (Lactuca serriola), common vetch (Vicia sativa), field bindweed (Convolvulus arvensis), and bristly ox-tongue (Picris echioides).
Mixed evergreen forest, composed primarily of the Douglas-fir series, occurs on the fringes of non-native grassland outside the fallow vineyard. Douglas-fir dominates the canopy, with a subcanopy of madrone, coast live oak, California black oak, and California buckeye. The mixed understory consists primarily of native shrubs including poison oak, toyon, coyote brush, and buckbrush (Ceanothus cuneatus).
West of the swale, within non-native grassland habitat, a highly disturbed area (approximately 1,000 square feet) was observed that appears seasonally wet due to minor subsurface discharge. Wetland-classified plant species, such as rabbitsfoot grass, spreading rush (Juncus patens), hairy willow-herb (Epilobium ciliatum), sedge (Carex sp.), two small individuals of narrow-leaved cattail, and one red willow were observed, along with wetland hydrology indicators.
Vegetation community descriptions are based on the June 19, 2006, field visit. After the June 19, 2006, visit, prior to the December 22, 2006, field visit, material dredged from the upper reservoir was deposited on a portion of the SMV project site. Non-native grassland habitat was altered by the deposition of fill material and subsequent grading. No other vegetation communities or habitats were affected.
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Table 6. Plant Species Observed within the Project Area Common Name Scientific Name9 Site10 big-leaf maple Acer macrophyllum UYCD, LYCR trail plant Adenocaulon bicolor UYCD chamise Adenostoma fasiculatum LYCR California maiden-hair Adiantum jordanii UYCD California buckeye Aesculus californica LYCR, SMV European hairgrass Aira caryophyllea LYCR white alder Alnus rhombifolia UYCD dog-fennel* Anthemis cotula UYCD elk clover Aralia californica UYCD Pacific madrone Arbutus menziesii UYCD, LYCR, SMV common manzanita Arctostaphylos manzanita ssp. LYCR manzanita wild oats* Avena sp. UYCD, LYCR, SMV coyote brush Baccharis pilularis UYCD, LYCR, SMV black mustard* Brassica nigra UYCD field mustard* Brassica rapa UYCD rattlesnake grass* Briza maxima UYCD, LYCR little quaking grass* Briza minor UYCD, LYCR harvest brodiaea Brodiaea elegans LYCR ripgut brome* Bromus diandrus UYCD, LYCR, SMV soft chess* Bromus hordeaceus UYCD, LYCR spicebush Calycanthus occidentalis UYCD shepherd’s purse* Capsella bursa-pastoris UYCD Italian thistle* Carduus pycnocephalus UYCD, LYCR sedge Carex spp. UYCD, SMV buckbrush Ceanothus cuneatus LYCR, SMV yellow star-thistle* Centaurea solstitialis UYCD, LYCR centaury Centaurium muehlenbergii LYCR soap plant Chorogalum pomeridianum UYCD, LYCR bull thistle* Cirsium vulgare UYCD clarkia Clarkia sp. LYCR poison hemlock* Conium maculatum LYCR field bindweed* Convolvulus arvensis UYCD, SMV California hazelnut Corylus cornuta var. californica UYCD cotoneaster* Cotoneaster sp. UYCD hedgehog dogtail* Cynosurus echinatus LYCR, SMV tall flatsedge Cyperus eragrostis UYCD, LYCR, SMV hairgrass Deschampsia sp. SMV wood fern Dryopteris arguta UYCD
9 Botanical nomenclature follows Hickman (1993). 10 Upper York Creek Dam and Reservoir = UYCD; Lower York Creek Reservoir = LYCR; Spring Mountain Vineyard = SMV
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Common Name Scientific Name9 Site10 spikerush Eleocharis macrostachya LYCR blue wildrye Elymus glaucus UYCD willow-herb Epliobium sp. UYCD hairy willow-herb Epilobium ciliatum SMV horsetail Equisetum sp. UYCD turkey mullein Eremocarpus setigerus LYCR buckwheat Eriogonum sp. UYCD California poppy Eschscholzia californica LYCR fescue Festuca sp. UYCD, LYCR, SMV fennel* Foeniculum vulgare UYCD, LYCR Oregon ash Fraxinus latifolia UYCD sweet-scented bedstraw Galium triflorum UYCD French broom* Genista monspessulana UYCD, LYCR geranium* Geranium dissectum SMV English ivy* Hedera helix UYCD toyon Heteromeles arbutifolia UYCD, LYCR Mediterranean barley* Hordeum marinum ssp. SMV gussoneanum barley* Hordeum murinum SMV Klamathweed* Hypericum perforatum UYCD cat’s-ear* Hypochaeris sp. UYCD Douglas iris Iris douglasiana LYCR toad rush Juncus bufonius LYCR spreading rush Juncus patens UYCD, SMV iris-leaved rush Juncus xiphioides LYCR prickly lettuce* Lactuca serriola UYCD, LYCR, SMV wild pea* Lathrys sp. UYCD tanoak Lithocarpus densiflorus UYCD Italian ryegrass* Lolium multiflorum UYCD, LYCR hairy honeysuckle Lonicera hispidula var. vacillans LYCR birdsfoot trefoil* Lotus corniculatus SMV deer brush Lotus scoparius UYCD, LYCR hyssop loosestrife* Lythrum hyssopifolium UYCD, LYCR tarweed Madia sp. UYCD, LYCR wild cucumber Marah fabaceus LYCR bur clover* Medicago polymorpha UYCD sticky monkeyflower Mimulus aurantiacus UYCD, LYCR musk monkeyflower Mimulus moschatus UYCD forget-me-not* Myosotis latifolia UYCD purple needlegrass Nassella pulchra LYCR sweet-cicely Osmorhiza chilensis UYCD, LYCR goldback fern Pentagramma triangularis UYCD Kellogg yampah Perideridia kelloggii LYCR Harding grass* Phalaris aquatica SMV
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Common Name Scientific Name9 Site10 bristly ox-tongue* Picris echioides UYCD, SMV pine* Pinus sp. LYCR foothill pine Pinus sabiniana LYCR English plantain* Plantago lanceolata UYCD, LYCR annual bluegrass* Poa annua UYCD knotweed Polygonum sp. UYCD, LYCR California polypody Polypodium californicum UYCD rabbits foot grass* Polypogon monspeliensis UYCD, LYCR, SMV Fremont cottonwood Populus fremontii ssp. fremontii LYCR Douglas-fir Pseudotsuga menziesii var. UYCD, LYCR menziesii bracken fern Pteridium aquilinum var. pubescens UYCD coast live oak Quercus agrifolia UYCD, LYCR blue oak Quercus douglasii LYCR California black oak Quercus kelloggii UYCD, LYCR, SMV valley oak Quercus lobata LYCR wild radish* Raphanus sativus UYCD water cress Rorippa nasturtium-aquaticum UYCD Himalayan blackberry* Rubus discolor UYCD, LYCR California blackberry Rubus ursinus UYCD curly dock* Rumex crispus UYCD, LYCR willow Salix sp. UYCD, LYCR narrow-leaved willow Salix exigua UYCD, LYCR red willow Salix laevigata UYCD, SMV shining willow Salix lucida ssp. lasiandra UYCD snakeroot Sanicula crassicaulis UYCD California bulrush Scirpus californicus LYCR redwood Sequoia sempervirens UYCD nightshade Solanum sp. UYCD prickly sow thistle* Sonchus asper UYCD, SMV hedgenettle Stachys sp. UYCD blue-eyed-grass Sisyrinchium bellum LYCR, SMV creeping snowberry Symphoricarpos mollis LYCR common dandelion* Taraxacum officianale UYCD, SMV torilis* Torilis arvensis UYCD poison oak Toxicodendron diversilobum UYCD, LYCR, SMV little hop clover* Trifolium dubium LYCR rose clover* Trifolium hirtum UYCD, SMV narrow-leaved cattail Typha angustifolia UYCD, LYCR, SMV California bay Umbellularia californica UYCD, LYCR stinging nettle Urtica dioica UYCD American brooklime Veronica americana UYCD common vetch* Vicia sativa UYCD, SMV periwinkle* Vinca major UYCD
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Common Name Scientific Name9 Site10 grape* Vitis sp. UYCD, LYCR vulpia* Vulpia sp. UYCD, SMV * = non-native species
Wetlands and Other Waters of the U.S. Wetlands include a variety of aquatic ecosystems, both permanent and ephemeral. They occur in nearly all continents and climes. Wetlands provide essential wildlife habitat, help maintain water quality, and control flooding. To protect these and other unique features of wetlands, wetland protection laws have been enacted by a number of government agencies. Jurisdictional wetlands11 and other “waters of the United States”12 are regulated by the Corps under the provisions of Section 404 of the Clean Water Act (33 United States Code [USC] §1344) and Section 10 of the Rivers and Harbors Act of 1899 (33 USC §403). Any filling of wetlands or waters requires a permit from the Corps. Under Section 401 of the federal Clean Water Act, the Corps is required to meet state water quality regulations prior to granting a Section 404 permit for work in a wetland, creek, river, or drainage. This is accomplished through certification that requirements have been met by the local Regional Water Quality Control Board under Section 401 of the Clean Water Act. In addition, the California Department of Fish and Game may regulate activities affecting or potentially affecting such resources under Section 1600 of the California Fish and Game Code. Projects affecting or potentially affecting such resources must obtain a Streambed Alteration Agreement from CDFG. Wetlands may also be subject to the local city or county regulations where the project takes place.
A routine wetland delineation of the project area was conducted on December 22, 2006 (Appendix 4). The purpose of the survey was to delineate all potential jurisdictional wetlands and other waters of the U.S. that could be impacted by project activities. The delineation followed protocols described in Corps of Engineers’, Wetland Delineation Manual (Environmental Laboratory 1987). Wetlands are identified using three diagnostic environmental characteristics: hydrophytic vegetation, hydric soils, and wetland hydrology. Under normal circumstances, jurisdictional wetlands exhibit all three diagnostic features. Potential jurisdictional wetlands and other waters occurring within the project area were located and mapped. Potential wetlands were delineated based on the presence of the three wetland parameters, and potential other waters, such as York Creek and the upper and lower reservoirs, were delineated based on the presence of at least one wetland parameter and the presence of an Ordinary High Water Mark (OHWM).
11 Wetlands are defined as “those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.” (Environmental Laboratory 1987) 12 Waters of the U.S. include, but are not limited to the following: any channel that has real or potential interstate commerce value including lakes, rivers, streams [including perennial and intermittent streams, and ephemeral streams that have an ordinary high water mark (OHWM)], tributaries to waters, mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa lakes, natural ponds, and impoundments of waters (33 CFR 328.3). The OHWM is described as the elevation delineating the highest water level that has been maintained for a sufficient period of time to leave evidence on the landscape.
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3.3.1.2 Existing Fish and Wildlife Resources Three general categories of environmental factors determine the variety and abundance of animal species within an area. These include vegetation, physical factors (soils, climate, etc.), and disturbance factors. Because vegetation reflects the other parameters to a great extent, the previously described vegetation types serve as an appropriate framework to which animal species in the area of the proposed project can be applied. The species described below are those that would be expected to occur on the project sites and/or in areas nearby where suitable habitat exists. Although the characteristic assemblages of species occur predictably within certain vegetation types, it should be recognized that relatively few species are restricted to a single habitat, and, indeed, some species may require more than one habitat type.
Wildlife surveys were conducted in the project area from early April 2006 to December 2006. During the surveys an inventory of observed fish and wildlife species was compiled (Table 7). Daytime surveys were conducted with the aid of binoculars. During the surveys, visual cues, calls, and songs were used to identify bird species. Drainages, stream channels, woody debris, and other plant material were examined for presence of mammals, amphibians, reptiles, fish, and macroinvertebrates.
Among vertebrates, two amphibian, one reptile, 38 bird, and two fish species were observed. In addition, two mammal species were directly observed during site visits, but evidence suggesting the presence of additional species (scat, tracks, and burrows) was documented. No special-status animal species were observed during the surveys. Common and scientific names of vertebrate species observed within the project area are provided in Table 7. General or focused surveys for invertebrates (insects, spiders, etc.) were not conducted.
Upper St. Helena Dam and Reservoir Aquatic and terrestrial habitats found within and surrounding the Upper York Creek Dam and Reservoir provide nesting opportunities, food, shelter, corridors or islands during migration, and a water source for a number of resident and migratory fish and wildlife species. Of particular importance is the presence of York Creek, which provides habitat for federally-listed steelhead and California Special Concern species foothill yellow-legged frog. Within the project area, York Creek is characterized as a “moderately entrenched riffle dominated channel with infrequently spaced pools, very stable plan and profile, stable banks on moderate gradients with low width/depth ratios and cobble dominant substrates” (NCRCD 2005). Resident rainbow trout occur above the dam, and steelhead, an anadromous form of rainbow trout, occur within the lower reaches of the watershed. Substrate composition directly below the dam is dominated by fine materials and is not suitable for spawning or rearing. Upstream of the reservoir, the substrate is primarily gravel and cobble and is beneficial for spawning and rearing. Invertebrates (macro and micro) are abundant within the channel and form the prey base for the aquatic system. Resident fishes (i.e., prickly sculpin) utilize the stream channel as well.
A small population of foothill yellow-legged frog occurs within the watershed. Within the impoundment above the dam, naturalized bullfrogs are known to occur. Habitat within the project reach is marginal for California red-legged frog. Shallows pools and pockets of water provide breeding habitat for common amphibians such as the Pacific chorus frog, which are
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most active during winter months, and aquatic salamanders (i.e., newts, giant salamanders) may also utilize the stream channel.
Upland riparian woodlands and forests provide suitable habitat for terrestrial birds, mammals, amphibians, and reptiles. Birds represent the most abundant and prominent wildlife species within the project area. Bird species typical of woodlands and forests, such as those found within the project area, are chestnut-backed chickadee, ruby and golden-crowned kinglets, Steller’s and western-scrub jays, American robin, winter wren, hermit thrush, common bushtit, and brown creeper. The most common finch species include house, purple, and lesser goldfinch. The dense understory also provides foraging and nesting habitat for ground dwelling species such as the California towhee, California quail, dark-eyed junco, and spotted towhees Additional migratory species likely to occur and possibly breed within the project area include orange crowned-warbler, Wilson’s warbler, Pacific-slope flycatcher, and vireos. Tree climbing birds are also abundant (i.e., pileated, Nuttall’s, downy, and hairy woodpeckers, white-breasted nuthatch, brown creeper). Large trees and snags provide nesting opportunities for cavity-nesting birds. Birds, like the black phoebe, are often seen sallying over water sources for aerial insects, and ducks (i.e., mallard) may utilize the reservoir and stream channel for foraging habitat.
Suitable foraging and breeding habitat also exists for raptors including American kestrel and Cooper’s, sharp-shinned, red-shouldered, and red-tailed hawks. Small vertebrates within the habitat are likely to serve as a food source for predatory birds. The large trees on site are prime habitat for nesting raptors. Nocturnal avian predators include northern spotted, western screech, great horned, northern pygmy, and northern saw-whet owls.
The woodland and forested habitats support a variety of mammals. The dense understory and tree cavities provide escape, cover, and nesting sites. The presence of a large number of vertebrate species may serve as a significant food source for larger predatory mammals (i.e., bobcat and mountain lion). Some of the most commonly observed mammals include western gray squirrel, dusky-footed woodrat, northern raccoon, and black-tailed deer. In addition, common bat species may forage over the site and potential roosting sites for various bat species exist in the crevices and tree hollows found throughout the area.
Native oaks found within the project area serve as a significant resource for many wildlife species. Acorns are an important food source for mammals and birds, including the western gray squirrel, Steller’s and western scrub jays, acorn woodpecker, and oak titmouse. Oak trees also provide cover, roosting sites, food storage sites, and nesting opportunities for native wildlife.
Woody debris piles and layers of duff provide habitat for amphibians such as California slender salamander and Ensatina. Additional amphibians, such as northwestern and arboreal salamanders, and western toad, may utilize the area during the breeding and/or non-breeding season. Common reptiles of this community include western fence lizard, alligator lizard, and snakes (i.e., gopher and garter snakes).
Ruderal areas provide marginal habitat for native species and are of limited importance for wildlife. Wildlife abundance and diversity are typically low and restricted to disturbance- adapted and urban species. Ground foraging birds including California towhee and mourning
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dove feed on the vegetation and invertebrates. Subterranean dwellers such as Botta’s pocket gopher, California mole, and several snake species may utilize these areas as well.
Lower York Creek Reservoir Habitats surrounding the LYCR support many of the same species described above in the UYCD section. The freshwater wetland and open water habitat provide additional resources for wildlife species. Freshwater wetlands fringing the reservoir provide important foraging and breeding habitat for amphibians such as the California red-legged frog and Pacific treefrog. Northwestern pond turtles utilize the mud banks for thermoregulation and nesting. Wading birds (i.e., green and great blue herons) forage in the shallows. Marsh birds, such as the red- winged blackbird, forage and nest within the cattails along the margins. Open water habitat provides foraging habitat for swimmers such as American coot, Canada goose, mallard, pied- billed grebe, bufflehead, and ruddy duck and aerial and upland waterbirds such as violet-green swallow and belted kingfisher, respectively.
Spring Mountain Vineyard Habitats surrounding and within the SMV site support many of the same upland species described above in the UYCD section. Non-native grassland is the dominant habitat type within the project area. Wildlife abundance and diversity are typically low within non-native grasslands and limited to disturbance-adapted and urban species. The most common bird species include ground foraging birds such as the dark-eyed junco, spotted towhee, and American robin. Subterranean foragers such as Botta’s pocket gopher and California mole commonly occur in grasslands. Small mice (i.e., deer mice), California vole, brush rabbit, black- tailed jackrabbit, and black-tailed deer can be found in this habitat type. Reptiles of this community include western fence lizard, alligator lizard, and snakes (i.e., gopher and garter). The seasonally wet area to the west of the swale, and outside the limits of grading, provides limited habitat due to its small size and ephemeral nature.
Table 7. Fish and Wildlife Species Observed within the Project Area Common Name13 Scientific Name Site14 Amphibians Pacific treefrog Hyla regilla LYCR bullfrog Rana catesbeiana UYCD Reptiles western fence lizard Sceloporus occidentalis UYCD, LYCR, SMV Birds Cooper’s hawk Accipiter cooperii LYCR red-winged blackbird Agelaius phoeniceus LYCR mallard Anas platyrhynchos LYCR western scrub-jay Aphelocoma californica LYCR, SMV oak titmouse Baeolophus inornatus LYCR Canada goose Branta canadensis LYCR
13 CDFG 2006b; CDFG 2000 14 Upper York Creek Dam and Reservoir = UYCD; Lower York Creek Reservoir = LYCR; Spring Mountain Vineyard = SMV
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Common Name13 Scientific Name Site14 bufflehead Bucephala albeola LYCR red-tailed hawk Buteo jamaicensis LYCR California quail Callipepla californica LYCR Anna’s hummingbird Calypte anna LYCR American goldfinch Cardeulis tristis SMV turkey vulture Cathartes aura LYCR, SMV brown creeper Certhia americana UYCD belted kingfisher Ceryle alcyon LYCR northern flicker Colaptes auratus UYCD, LYCR, SMV American crow Corvus brachyrhynchos LYCR common raven Corvus corax LYCR Steller’s jay Cyanocitta stelleri UYCD yellow-rumped warbler Dendroica coronata LYCR pileated woodpecker Dryocopus pileatus UYCD, LYCR Pacific-slope flycatcher Empidonax difficilis UYCD American coot Fulica americana LYCR dark-eyed junco Junco hyemalis SMV acorn woodpecker Melanerpes formicivorous LYCR song sparrow Melospiza melodia UYCD, LYCR band-tailed pigeon Patagioenas fasciata LYCR spotted towhee Pipilo maculatus UYCD, LYCR, SMV chestnut-backed chickadee Poecile rufescens SMV bushtit Psaltriparus minimus UYCD, SMV ruby-crowned kinglet Regulus calendula UYCD, SMV black phoebe Sayornis nigricans UYCD, LYCR, SMV violet-green swallow Tachycineta thalassina UYCD, LYCR winter wren Troglodytes troglodytes UYCD American robin Turdus migratorius UYCD western kingbird Tyrannus verticalis LYCR orange-crowned warbler Vermivora celata LYCR, SMV Wilson’s warbler Wilsonia pusilla UYCD mourning dove Zenaida macroura UYCD Mammals Odocoileus hemionus black-tailed deer (mule deer) UYCD columbianus raccoon Procyon lotor UYCD, LYCR western gray squirrel Sciurus griseus UYCD Fish prickly sculpin Cottus asper UYCD rainbow trout Oncorhynchus mykiss UYCD
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3.3.1.3 Special-Status Species Special-status species are taxa listed as endangered or threatened by the U.S. Fish and Wildlife Service, NOAA’s National Marine Fisheries Service (NOAA’s Fisheries Service), or California Department of Fish and Game; taxa designated as candidates for listing; or any species of concern or local concern. In addition, the California Native Plant Society has compiled a list of plant species that it considers to be rare, threatened, or endangered. Consideration of these plants must be included during project evaluation in order to comply with the California Environmental Quality Act (CEQA) Guidelines concerning special-status species.
Special-status species of California include: • Plant and animal species designated as threatened or endangered under the federal Endangered Species Act. • Species designated as threatened or endangered by CDFG under the California Endangered Species Act. • Species that are recognized as candidates for listing by agencies with resource management responsibilities such as U.S. Fish and Wildlife Service, California Department of Forestry and Fire Protection (CDF), USDA Forest Service (FS), Bureau of Land Management (BLM), NOAA’s National Marine Fisheries Service, and California Department of Fish and Game. • Species defined by CDFG as California Special Concern species. • Species classified as Fully Protected by CDFG. • Species considered rare, threatened, or endangered pursuant to Section 15380 of the CEQA Guidelines. • Plant species, subspecies, and varieties defined as rare or threatened by the California Native Plant Protection Act (California Fish & Game Code Section 1900 - 1913). • Plant species assigned to the California Native Plant Society List: List 1A (plants presumed extinct in California), List 1B (plants rare or endangered in California and elsewhere), and List 2 (plants rare or endangered in California, more common elsewhere). • Species protected by the federal Migratory Bird Treaty Act (MBTA) (16 USC §703-712). • Bald and golden eagles protected by the federal Bald and Golden Eagle Protection Act (BGEPA) (16 USC §668a-d).
3.3.1.4 Special-Status Species within the Project Area In addition to evaluating the presence of special-status species during on-site biological surveys, data available from the CDFG California Natural Diversity Data Base for the St. Helena, Rutherford, Calistoga, and Kenwood 7.5’ USGS quadrangles were reviewed to determine potentially-occurring rare, threatened, or endangered animal and plant species within the project area (CDFG 2006a). The CNDDB reports occurrences of special-status species that have been entered into the database and does not generally include inventories of more common animals or plants. The absence of a species from the database does not necessarily mean that they do not occur in the area, only that no sightings have been reported. In addition, sightings are subject to observer judgment and may not be entirely reliable as a result. The CNPS Inventory of Rare and Endangered Vascular Plants of California on-line inventory (CNPS 2006) was also reviewed for potentially-occurring special-status plants as well as USFWS on-line
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species lists for the St. Helena, Rutherford, Calistoga, and Kenwood quadrangles and Napa County (USFWS 2006).
Special-Status Plants Based on the background literature search discussed above, 32 special-status plant species are documented to occur in the project area’s region (St. Helena, Rutherford, Calistoga, and Kenwood 7.5’ USGS quadrangles). Table 8 lists the potentially occurring special-status plants, their listing status, habitat association, and potential for occurrence within the project area. Based on the suitability of habitat within the project area and proximity of recorded sightings, these species were evaluated for potential occurrence within the project area. Twenty-three species were determined to be absent or have a low potential for occurrence on the project area due to a lack of suitable habitat and are, therefore, not likely to be impacted by project activities.
The remaining nine special-status plant species occur in general habitat types found within the project area. The habitats on the project area are generally disturbed, and none of these species are considered to have a high potential for occurrence. However, these species are considered to have a moderate potential to occur on the project area based on the presence of suitable habitat and other factors, such as documented occurrences in the general vicinity. For these species, status and life history characteristics are described in further detail below. Of the nine special- status plant species that occur in habitat types found on the project area, six are considered absent from the project area because a plant survey (June 19, 2006) was conducted during their recorded blooming period (CNPS 2006), and they were not observed. For the remaining three species, focused surveys in spring 2007 will be completed to determine their presence or absence.
Table 8. Special-Status Plant Species Considered in Project Evaluation Listing Status15 Potential for Species Common Name Scientific Name (Federal/ General Habitat Occurrence within the State/ Project Area CNPS) Moderate. Marginal suitable habitat in mixed Cismontane evergreen forest on slopes Allium woodland, valley above upper reservoir and Franciscan peninsulare var. and foothill surrounding SMV, and in onion --/--/ List 1B grassland (clay, franciscanum often serpentinite), grassland and woodland 330-985 feet. surrounding lower Blooms May-June. reservoir. Serpentine observed east of Spring Mountain Road. Moderate. Potential Alopecurus Marshes and swamps suitable habitat is present Sonoma aequalis var. FE/--/List 1B (freshwater), in riparian woodland alopecurus sonomensis riparian scrub, 15- along upper reservoir and 1,200 feet. Blooms freshwater wetland at the May-July. lower reservoir. Amorpha Napa false --/--/List 1B Broadleafed upland Moderate. Potential californica var. forest (openings), suitable habitat present in
15 See CDFG (2007a) and CDFG (2007b).
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Listing Status15 Potential for Species Common Name Scientific Name (Federal/ General Habitat Occurrence within the State/ Project Area CNPS) indigo napensis chaparral, mixed evergreen forest cismontane surrounding upper woodland, 395- 6,560 feet. Blooms reservoir and SMV. Three April-July. occurrences within 3.0 miles of upper reservoir. Chaparral (highly Not present. No suitable Arctostaphylos restricted to red habitat present within the Rincon stanfordiana ssp. rhyolites in --/--/List 1B Sonoma County), project area. Species is manzanita decumbens 245-1,215 feet. known from fewer than 10 Blooms February- occurrences, all in Sonoma April. County. Chaparral Moderate. Some suitable (openings), cismontane habitat present in non- woodland, valley native grassland fringing Astragalus and foothill lower reservoir. Clara Hunt’s claranus FE/SE/List 1B grassland (open Documented historic milk-vetch grassy hillsides, occurrence adjacent to serpentinite or lower reservoir, and three volcanic, rocky other occurrences within clay), 245-900 feet. Blooms March- three miles. May. Moderate. Potential Brodiaea Broadleafed upland suitable habitat present in narrow- forest, chaparral, anthered californica var. lower montane mixed evergreen forest, California leptandra --/--/List 1B coniferous forest, primarily around upper brodiaea 330-3,000 feet. reservoir. Three Blooms May-July. occurrences within five miles of project area. Closed-cone Low. No suitable habitat coniferous forest, chaparral, present within the project area. Ceanothus cismontane Rincon Ridge woodland. Known confusus --/--/List 1B from volcanic or ceanothus serpentinite soils, dry shrubby slopes, 245-3,500 feet. Blooms February- April. Ceanothus Chaparral Not present. No suitable Calistoga (serpentine or divergens --/--/List 1B volcanic, rocky), habitat present within the ceanothus project area. 560-3,115 feet. Blooms Feb-March. Chaparral, Not present. No suitable Ceanothus cismontane habitat present within the holly-leaved woodland purpureus --/--/List 1B (volcanic, rocky), project area. ceanothus 395-2,100 feet. Blooms February- June. Ceanothus Chaparral (sandy, Not present. No suitable Sonoma sonomensis --/--/List 1B serpentinite, or habitat present in project ceanothus volcanic), 705-2,625 area. Project occurs below feet. Blooms the recorded elevational
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Listing Status15 Potential for Species Common Name Scientific Name (Federal/ General Habitat Occurrence within the State/ Project Area CNPS) February-April. range of the species. Coastal prairie, Low. Project area lacks meadows and seeps, marshes and suitable alkaline habitat for the species. Centromadia swamps (coastal pappose salt), valley and parryi ssp. parryi --/--/List 1B foothill grassland tarplant (vernally mesic/often alkaline), 7-1,380 feet. Blooms May- November. Downingia Valley and foothill Low. Project area lacks dwarf grassland (mesic), pusilla --/--/List 2 vernal pools, 3- suitable vernal pool downingia habitat for the species. 1,460 feet. Blooms March-May. Erigeron Chaparral Low. No suitable habitat narrow-leaved (serpentinite or angustatus --/--/List 1B volcanic), 260-950 present within the project daisy area. feet. Blooms May- September. Low. Project area lacks Eryngium suitable vernal pool Loch Lomond Vernal pools, 1,510- habitat for the species and button-celery constancei FE/SE/List1B 2,805 feet. Blooms April-June. occurs below the recorded elevational range of the species. Coastal scrub, Low. Non-native valley and foothill grassland at SMV may grassland, coastal provide some marginal fragrant Fritillaria liliacea --/--/List 1B prairie. Often on habitat, but lack of suitable fritillary serpentinite or clay, substrate and extensive 10-1,345 feet. recent disturbances make Blooms February- the species presence April. unlikely. Hesperolinum Chaparral two-carpellate Low. No suitable habitat bicarpellatum --/--/List 1B (serpentinite), 200- present within the project western flax 3,300 feet. Blooms May-July. area. Hesperolinon Chaparral Napa western Low. No suitable habitat serpentinum --/--/List 1B (serpentinite), 165- present within the project flax 2,625 feet. Blooms May-July. area. Not present. Suitable riparian habitat present, Northern Juglans Riparian forest, riparian woodland, but species not observed California black californica var. --/--/List 1B 0-1,445 feet. Blooms during field visits. Very walnut hindsii April-May. few native occurrences, most have been naturalized (CNPS 2006). Chaparral, Moderate. Potential Layia cismontane Colusa layia septentrionalis --/--/List 1B woodland, valley suitable habitat present in non-native grassland and foothill grassland. along lower reservoir and,
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Listing Status15 Potential for Species Common Name Scientific Name (Federal/ General Habitat Occurrence within the State/ Project Area CNPS) Scattered colonies though less likely, ruderal in fields and grassy grassland in the vicinity of slopes in sandy or serpentine soils, the dam berm at the upper 475-3,590 feet. reservoir. Blooms April-May. Chaparral, Moderate. Potential cismontane woodland, open to suitable habitat present in Leptosiphon partially shaded non-native grassland Jepson’s along lower reservoir and, jepsonii --/--/List 1B grassy slopes on leptosiphon volcanics or though less likely, ruderal periphery of grassland in the vicinity of serpentine, 330- the dam berm at the upper 1,640 feet. Blooms reservoir. April-May. Chaparral, Low. Suitable habitat not cismontane woodland, lower present. Project area montane coniferous occurs near the lowest forest. In stands of elevational limit of the Cobb Mountain Lupinus sericatus knobcone pine-oak species. --/--/List 1B woodland, on open lupine wooded slopes in gravelly soils, sometimes on serpentine, 590- 4,920 feet. Blooms March-June. Cismontane Low. Suitable vernal pool woodland, lower montane coniferous habitat and substrate not forest, meadows present within the project Navarretia and seeps, valley area. Baker’s leucocephala ssp. and foothill --/--/List 1B grassland, vernal navarretia bakeri pools, 15-5,700 feet. Primarily in vernal pools/swales with adobe or alkaline soils. Blooms April- July. Penstemon Low. Project area occurs Sonoma newberryi var. Chaparral (rocky), below the recorded --/--/List 1B 2,300-4,500 feet. beardtongue sonomensis Blooms April-Aug. elevational range of the species. Low. Project area lacks Meadows and suitable alkaline habitat seeps, valley and for the species. Known foothill grassland, from only a few extant Plagiobothrys Calistoga vernal pools occurrences near strictus FE/SE/List 1B (alkaline areas near Calistoga. Previous studies popcorn-flower thermal springs), (DWR 2003) considered 295-525 feet. portions of the upper Blooms March- June. reservoir suitable habitat but did not locate it during focused surveys. Napa blue grass Poa napensis FE/SE/List 1B Meadows and Not present. Project area
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Listing Status15 Potential for Species Common Name Scientific Name (Federal/ General Habitat Occurrence within the State/ Project Area CNPS) seeps, valley and lacks suitable alkaline foothill grassland habitat for the species. (alkaline, near thermal springs), 330-660 feet. Blooms May- August. Sidalcea Chaparral Low. No suitable habitat Marin hickmanii ssp. present within the project --/--/List 1B (serpentinite), 165- checkerbloom viridis 1,410 feet. Blooms area. May-June. Meadows and Low. Project area occurs seeps, riparian Sidalcea oregana below the recorded marsh forest. Wet soil of ssp. hydrophila --/--/List 1B streambanks, elevational range of the checkerbloom meadows, 3,600- species. 7,545 feet. Blooms July-August. Moderate potential. Marshes and Potential suitable habitat Sidalcea oregana Kenwood Marsh swamps present in riparian ssp. valida FE/SE/List 1B (freshwater), 375- woodland along upper checkerbloom 490 feet. Blooms reservoir and freshwater June-September. wetland fringing the lower reservoir. Chaparral Low. Project area lacks (openings), Streptanthus cismontane suitable microhabitat. green jewel- breweri var. --/--/List 1B woodland flower hesperidis (serpentinite, rocky), 425-2,490 feet. Blooms May- July. Valley and foothill Low. Project area lacks grassland, coastal bluff scrub. suitable microhabitat. Sometimes on Only two known Trifolium serpentine soil, remaining occurrences, in showy Indian amoenum FE/--/List 1B open sunny sites, western Sonoma County. clover swales. Most recently sited on roadside and eroding cliff face. 16-1,840 feet. Blooms April-June. Marshes and Low. Project area lacks Trifolium swamps, valley and suitable alkaline habitat depauperatum foothill grassland, saline clover --/--/List 1B vernal pools, mesic, for the species. var. hydrophilum alkaline sites, 0-985 feet. Blooms April- June. Chaparral, Moderate. Potential Viburnum cismontane oval-leaved suitable habitat present in ellipticum --/--/List 2 woodland, lower mixed evergreen forest viburnum montane coniferous forest, 400-4,590 along the upper reservoir feet. Blooms May- and SMV.
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Listing Status15 Potential for Species Common Name Scientific Name (Federal/ General Habitat Occurrence within the State/ Project Area CNPS) June.
FEDERAL: FE = Listed as endangered, in danger of extinction.
STATE: SE = State-listed as endangered.
CNPS: List 1B = Rare, threatened, or endangered in California and elsewhere. List 2 = Rare, threatened, or endangered in California, but more common elsewhere.
Special-Status Plant Descriptions The following descriptions include those species that occur in habitat types found within the project area, and species that could potentially occur on one or more project sites based on the presence of suitable habitat and documented occurrences within the general project area region.
Franciscan onion (Allium peninsulare var. franciscanum) Status: CNPS List 1B.
Franciscan onion is a perennial herb in the Liliaceae family. It generally occurs on dry slopes in cismontane woodland, valley and foothill grassland, often on clay or serpentinite substrates, between 330 and 985 feet elevation. The species blooms May through June (CNPS 2006). The nearest documented occurrence is located approximately 7.0 miles southwest of the upper reservoir (CDFG 2006a). Marginal suitable habitat occurs within the project area in mixed evergreen forest on slopes above the upper reservoir and surrounding SMV, and in grassland and woodland surrounding the lower reservoir. Serpentine was observed along Spring Mountain Road. Previous geologic investigations (Corps 2006) of the upper reservoir identified serpentinite at relatively shallow depths in the vicinity of the dam, and the Soil Survey of Napa County, California (USDA 1978) maps soils of the Henneke Series (which are derived from material weathered from serpentine) adjacent to and west of the lower reservoir. A field visit was conducted during Franciscan onion’s recorded blooming period (CNPS 2006). It was not observed and is, therefore, considered absent from the project area.
Sonoma alopecurus (Alopecurus aequalis var. sonomensis) Status: Federally-listed as endangered, CNPS List 1B.
Sonoma alopecurus is a perennial grass in the Poaceae family. It occurs in freshwater marshes and swamps, riparian scrub, and on riparian banks generally with other wetland species, between 15 and 1,200 feet elevation. The species blooms May through July (CNPS 2006). The nearest documented occurrence is approximately 8.5 miles southwest of the upper reservoir (CDFG 2006a). Potential suitable habitat is present in riparian woodland along the upper reservoir and freshwater wetland fringing the lower reservoir. A field visit was conducted
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during the recorded blooming period (CNPS 2006) of Sonoma alopecurus. It was not observed and is, therefore, considered absent from the project area.
Napa false indigo (Amorpha californica var. napensis) Status: CNPS List 1B.
Napa false indigo is a shrub in the Fabaceae family. It occurs in openings in broadleafed upland forest, chaparral, and cismontane woodland, between 395 and 6,560 feet elevation. The species blooms April through July (CNPS 2006). The nearest documented occurrence is located approximately 1.8 miles north of the upper reservoir, with an additional two occurrences located within 3 miles of the upper reservoir (CDFG 2006a). Potential suitable habitat is present in mixed evergreen forest surrounding the upper reservoir and SMV. A field visit was conducted during the recorded blooming period (CNPS 2006) of Napa false indigo. It was not observed and is, therefore, considered absent from the project area.
Clara Hunt’s milk-vetch (Astragalus claranus) Status: Federally and state-listed as endangered, CNPS List 1B.
Clara Hunt’s milk-vetch is an annual herb in the Fabaceae family. It occurs in chaparral, cismontane woodland, valley and foothill grassland, often in open grassy hillsides with serpentinite or volcanic substrates, between 245 and 900 feet elevation. The species blooms March through May (CNPS 2006). The nearest documented occurrence occurs immediately east of the lower reservoir, though this occurrence was mapped generally, is historic, and possibly extirpated. An additional three occurrences occur within 3.0 miles of the lower reservoir (CDFG 2006a). Potential suitable habitat is present in non-native grassland above the lower reservoir. Though this area is disturbed, the Soil Survey of Napa County, California (USDA 1978) maps soils of the Henneke Series (which are derived from material weathered from serpentine) adjacent to and west of the lower reservoir. The field visits occurred outside the recorded blooming period (CNPS 2006) of Clara Hunt’s milk-vetch, and a spring 2007 survey will be completed to determine the presence or absence of this species within the project area.
Narrow-anthered California brodiaea (Brodiaea californica var. leptandra) Status: CNPS List 1B.
Narrow-anthered California brodiaea is a perennial herb in the Liliaceae family. It occurs in broadleafed upland forest, chaparral, and lower montane coniferous forest, between 330 and 3,000 feet elevation. The species blooms May through July. The nearest documented occurrence occurs approximately 2.7 miles northeast of the project area, with an additional two occurrences within 5.0 miles (CDFG 2006). Potential suitable habitat is present within mixed evergreen forest, primarily near the upper reservoir. A field visit was conducted during the recorded blooming period (CNPS 2006) of narrow-anthered California brodiaea. It was not observed and is, therefore, considered absent from the project area.
Kenwood Marsh checkerbloom (Sidalcea oregana ssp. valida) Status: Federally and state-listed as endangered, CNPS List 1B.
Kenwood Marsh checkerbloom is a perennial herb in the Malvaceae family. It occurs in freshwater marshes and swamps, between 375 and 490 feet elevation. The species blooms June
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through September (CNPS 2006). The nearest documented occurrence is located approximately 7.0 miles southwest of the project area (CDFG 2006). Potential suitable habitat is present in riparian woodland along the upper reservoir and freshwater wetland fringing the lower reservoir. A field visit was conducted during the recorded blooming period (CNPS 2006) of Kenwood Marsh checkerbloom. It was not observed and is, therefore, considered absent from the project area.
Oval-leaved viburnum (Viburnum ellipticum) Status: CNPS List 2.
Oval-leaved viburnum is a shrub in the Caprifoliaceae family. It occurs in chaparral, cismontane woodland, and lower montane coniferous forest, between 400 and 4,590 feet elevation. The species blooms May through June (CNPS 2006). The nearest documented occurrence is approximately 5.0 miles southwest of the project area. Potential suitable habitat is present in mixed evergreen forest along the upper reservoir and SMV. A field visit was conducted during the recorded blooming period (CNPS 2006) of oval-leaved viburnum. It was not observed and is, therefore, considered absent from the project area.
Colusa layia (Layia septentrionalis) Status: CNPS List 1B.
Colusa layia is an annual herb in the Asteraceae family. It occurs in chaparral, cismontane woodland, and valley and foothill grassland, generally in scattered colonies in fields and grassy slopes in sandy or serpentine soils, between 475 and 3,590 feet elevation. The species blooms April through May (CNPS 2006). The nearest documented occurrence is located approximately 3.5 miles southwest of the project area (CDFG 2006a). Potential suitable habitat is present in non-native grassland along the lower reservoir and, though less likely, ruderal grassland in the vicinity of the dam berm and along Spring Mountain Road at the upper reservoir. Previous geologic investigations (Corps 2006) of the upper reservoir identified serpentinite at relatively shallow depths in the vicinity of the dam. In addition, the Soil Survey of Napa County, California (USDA 1978) maps soils of the Henneke Series (which are derived from material weathered from serpentine) adjacent to and west of the lower reservoir. The field visits occurred outside the recorded blooming period (CNPS 2006) of Colusa layia, and a spring 2007 survey will be completed to determine the presence or absence of this species within the project area.
Jepson’s leptosiphon (Leptosiphon jepsonii) Status: CNPS List 1B.
Jepson’s leptosiphon is an annual herb in the Polemoniaceae family. It occurs in chaparral, cismontane woodland, generally in open to partially shaded grassy slopes on volcanics or periphery of serpentine, between 330 and 1,640 feet elevation. The species blooms April through May (CNPS 2006). The nearest documented occurrence is located approximately 3.5 miles east of the project area (CDFG 2006a). Potential suitable habitat is present in non-native grassland along the lower reservoir and, though less likely, in ruderal grassland in the vicinity of the dam berm and along Spring Mountain Road at the upper reservoir. Previous geologic investigations (Corps 2006) of the upper reservoir identified serpentinite at relatively shallow depths in the vicinity of the dam. In addition, the Soil Survey of Napa County, California (USDA 1978) maps
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soils of the Henneke Series (which are derived from material weathered from serpentine) adjacent to and west of the lower reservoir and soils of the Forward Series, which are weathered from rhyolite, around the upper reservoir. The field visits occurred outside the recorded blooming period (CNPS 2006) of Jepson’s leptosiphon, and a spring 2007 survey will be completed to determine the presence or absence of this species within the project area.
Special-Status Natural Communities The reviewed records indicate the occurrence of three special-status natural communities: coastal and valley freshwater marsh, northern vernal pool, and valley needlegrass grassland. These communities are not present within the project area and are not likely to be impacted by project activities (Table 9).
Table 9. California Natural Communities Considered in Project Evaluation
Common Name General USGS Quad(s) Potential for 16 Occurrence Description within the Project Area Not present. Freshwater wetland fringing lower reservoir has similar Dominated by perennial, characteristics but Coastal and Valley emergent monocots 12 to 15 results from man-made Freshwater Marsh feet tall, often forming closed Calistoga water impoundment canopies. and is considered a sensitive community only as it relates to jurisdictional wetlands. A low, amphibious, herbaceous community St. Helena, Northern Vernal Pool dominated by annual herbs Kenwood Not present. and grasses A midheight (up to 2 feet) Valley Needlegrass grassland dominated by the Grassland perennial purple needlegrass Kenwood Not present. (Nassella pulchra)
3.3.1.5 Special-Status Animals The reviewed records identified the potential presence of a number of special-status animal species within the project area. Table 10 lists the potentially occurring special-status animals, their listing status, habitat association, and potential for occurrence within the project area. Based on the suitability of habitat within the project area and proximity of recorded sightings, these species were evaluated for potential occurrence within the project area. For those special- status animal species that occur in habitat types found within the project area and/or that have reported sightings within close proximity to the project sites, status and life history characteristics are described in further detail below (Zeiner, et al., 1990). The remaining species do not occur in habitat types found within the project area, and/or have no local occurrences and are not likely to be impacted by project activities.
16 Descriptions generally follow Holland (1986).
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Table 10. Special-Status Animal Species Considered in Project Evaluation Listing 17 Status Potential for Common Name Scientific (Federal/ General Habitat Species Occurrence Name within the Project State/ Area Other) AMPHIBIANS Marshes, streams, lakes, Low to moderate. reservoirs, ponds, and Suitable habitat California red- FT/CSC/-- other water sources with occurs within the legged frog Rana aurora plant cover. Breeding project area. draytonii occurs in deep, slow However, no local moving waters with dense, sightings for this shrubby, or emergent species have been vegetation. documented. Low to moderate. Suitable habitat foothill yellow- In or near partly shaded occurs within the legged frog rocky streams that are project area. Rana boylii --/CSC/-- shallow, slow, and However, no local moderately-sized. sightings for this species have been documented. REPTILES In or near permanent or Moderate to high. northwestern pond Emys semi-permanent water Suitable habitat is turtle (=Clemmys) sources (i.e., ponds, lakes, present at the LYCR marmorata --/CSC/-- rivers, streams) with and marginal habitat marmorata suitable basking sites and at the UYCD. underwater retreats. BIRDS Forages across a wide range High potential. sharp-shinned Suitable foraging hawk (nesting) Accipiter --/CSC/-- of habitats and breeds in striatus mixed forest and woodland and nesting habitat occurs within the habitats. project area. Low to moderate. Suitable breeding Freshwater marsh habitat and foraging habitat tricolored blackbird with emergent tules, for this species (nesting colony) Agelaius BCC/CSC/ occurs along the tricolor Watch List cattails, or other vegetation margins of the lower for nesting and open areas reservoir. No local for foraging. sightings for this species have been documented. Present. Suitable Forested and deciduous foraging and oak titmouse Baeolophus --/--/Watch habitats, nests in artificial breeding habitat inornatus List and natural holes or present within the crevices. project area. Observed within the
17 See CDFG (2006c) and CDFG (2006d).
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Listing 17 Status Potential for Common Name Scientific (Federal/ General Habitat Species Occurrence Name within the Project State/ Area Other) project area. Not present. Forages in open sky Suitable foraging black swift preferring mountain habitat present but (nesting) Cypseloides BCC/CSC/ country and sea cliffs. nesting sites absent niger Watch List Breeds in these habitat from project area. types often behind No local sightings waterfalls. for this species have been documented. Occurs in a variety of High potential. habitat types during non- Suitable foraging breeding season and and breeding habitat yellow warbler Dendroica migration including present within the (nesting) --/CSC/-- riparian woodlands, mixed project area. petechia woodlands, urban gardens brewsteri and farmland. Partial to lowland riparian woodlands during the breeding season. Woodland, wetland, forest, Low potential. American Delisted - Falco BCC/ SE - and coastal habitats as well Suitable foraging peregrine falcon Fully as agricultural areas and habitat present but (nesting) peregrinus cities. Typically nest on cliff anatum Protected/ nesting habitat ledges and manmade absent from the -- structures. project area. Not present. Suitable foraging FT-FPD/ bald eagle (nesting Coastal and inland and nesting habitat and wintering) Haliaeetus SE-Fully waterways including large- not present within leucocephalus Protected/ bodied rivers, lakes, the project area.
-- seashores. Waterbodies present are too small to support bald eagles. Low to moderate. Suitable foraging yellow-breasted Dense riparian thickets habitat present chat (nesting) adjacent to stream within the project Icteria virens --/CSC/-- channels, ponds, and area. No local brushy thickets. sightings for this species have been documented.
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Listing 17 Status Potential for Common Name Scientific (Federal/ General Habitat Species Occurrence Name within the Project State/ Area Other) Moderate potential. Suitable foraging habitat occurs Riparian and oak within the project Purple martin woodlands, coniferous and area. Nesting sites (nesting) montane forests at high Progne subis --/CSC/-- elevations. Forages over limited to surrounding open land and water and forested woodlands. nests in tree cavities. No local sightings for this species have been documented. Dense forest habitats in Moderate potential. Strix northern California. Suitable foraging northern spotted Requires multi-layered and breeding habitat owl occidentalis FT/-- caurina /Watch List canopy cover for roosting occurs within the sites. Breeding sites include project area region. tree or snag cavities or broken tops of large trees. MAMMALS Moderate potential. pallid bat Antrozous Grassland, shrubland, Suitable roosting --/CSC/-- forest, and woodland and foraging habitat pallidus habitats at low elevations. occurs within the project area. Low to mid-elevation mesic Low to moderate. Townsend’s big- habitats including riparian, Suitable foraging eared bat Corynorhinus --/CSC/-- townsendii mixed forest, coniferous habitat present but forest, prairies, and roosting sites absent. agricultural lands. FISH Euryhaline habitats along Not present. FT/ST/ Delta smelt Hypomesus the lower and middle Suitable habitat for transpacificus AFS- reaches of the Sacramento- this species does not Threatened San Joaquin Delta. Tolerant occur within the of a wide range of salinities. project area. Majority of life spent in Not present. open ocean. Reproduces in Historically cool freshwater streams. occurred within the coho salmon- Occurs from Punta Gorda Napa River central California Oncorhynchus FE/SE/-- in northern California watershed. coast south to the San Lorenzo kisutch River in central California, including San Francisco Bay, excluding the Sacramento-San Joaquin River Delta.
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Listing 17 Status Potential for Common Name Scientific (Federal/ General Habitat Species Occurrence Name within the Project State/ Area Other) Majority of life spent in Present. Central open ocean. Reproduces in California coastal cool freshwater streams. ESU steelhead are Occurs below natural and known within the manmade impassable York Creek barriers in California watershed, steelhead-central FT/--/-- California coastal Oncorhynchus streams from the Russian downstream of the ESU mykiss River (inclusive) to Aptos dam. Creek (inclusive), and the drainages of San Francisco, San Pablo, and Suisun Bays, excluding the Sacramento- San Joaquin River Basin, as well as two propagated stocks. Majority of life spent in Not present. Project open ocean. Reproduces in area outside of the cool, perennial, freshwater range of this ESU. streams and rivers. Occurs steelhead-Central Oncorhynchus FT/--/-- from Sacramento and San Valley ESU mykiss Joaquin Rivers and their tributaries, excluding steelhead from San Francisco and San Pablo Bays and their tributaries. Majority of life spent in Not present. Project Chinook salmon- open ocean. Reproduces in area outside of the California coastal Oncorhynchus perennial coastal streams range of this ESU. ESU FT/--/-- and rivers. Occurs from tshawytscha south of the Klamath River to the Russian River, and seven propagated stocks. Majority of life spent in Not present. Project open ocean. Reproduces in area outside of the Chinook salmon- perennial coastal streams range of this run. Central Valley Oncorhynchus and rivers. Spring-run spring-run FT/ST/-- occurs in Sacramento River tshawytscha and its tributaries, as well Feather River and Feather River Hatchery spring-run Chinook program. Majority of life spent in Not present. Project open ocean. Reproduces in area outside of the perennial coastal streams range of this run. and rivers. Winter-run Chinook salmon FE/SE/-- (Sacramento River) occurs in Sacramento River Oncorhynchus winter-run tshawytscha and its tributaries, as well as two propagated stocks from Livingston Stone National Fish Hatchery and University of California Bodega Marine Laboratory.
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Listing 17 Status Potential for Common Name Scientific (Federal/ General Habitat Species Occurrence Name within the Project State/ Area Other) Not present. Suitable habitat for Majority of life spent in this species does not open ocean. Reproduces in occur within the Chinook salmon- perennial coastal streams project area. Central Valley Oncorhynchus SC/--/-- and rivers. Occurs from Chinook salmon fall/late fall-run tshawytscha Sacramento and San have been observed Joaquin Rivers Basins and sporadically in the their tributaries, east of Napa River and are Carquinez Strait. thought to be Central Valley strays. INVERTEBRATES Not present. Project areas lack suitable Riparian woodlands host plants and is valley elderberry Desmocerus throughout the Central outside the range of longhorn beetle californicus FT/--/-- Valley, CA on or near host this species. No local dimorphus plant, elderberry (Sambucus sightings for this sp.). species have been documented. Not present. Suitable habitat with FE/-- Coastal scrub and associated host callippe silverspot Speyeria grassland habitats in the plants does not butterfly /Xerces: callippe critically San Francisco Bay region. occur within the callippe Utilizes Viola pedunculata as project area. No imperiled a host plant. local, recent sightings have been documented. Low potential. Marginally suitable Low-elevation and aquatic habitat gradient, perennial streams occurs upstream and California in Marin, Sonoma, and downstream of freshwater shrimp Syncaris FE/SE/-- UYCD. This species pacifica Napa counties among is not known to undercut banks, rootwads, occur in the York and overhanging Creek watershed, vegetation. and no local, recent sightings have been documented.
LISTING STATUS CODES:
FEDERAL: FE = Listed as endangered, in danger of extinction. FT = Listed as threatened, likely to become endangered within the foreseeable future. FPD = Proposed for delisting. BCC = Bird of Conservation Concern. Delisted = Delisted species, monitored for 5 years. SC = Species of Concern- list established by NOAA’s National Marine Fisheries Service effective 15 April 2004.
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STATE: SE = State-listed as endangered. ST = State-listed as threatened. CSC = California Special Concern species. Fully Protected = Fully protected.
Other: WatchList = Listed on Audubon WatchList. Xerces: Critically Imperiled = Listed on Xerces Society red list of pollinators as critically imperiled. AFS: Threatened = Listed by American Fisheries Society as threatened.
Special-status Animal Descriptions The following descriptions include those special-status animal species that occur in habitat types found within the project area and/or that have reported sightings within close proximity to the project sites based on the background literature search.
Amphibians
California red-legged frog (Rana aurora draytonii). The California red-legged frog (CRLF) was listed as threatened on May 23, 1996, by U.S. Fish and Wildlife Service (61 FR 25813) and is listed as a California Special Concern species by CDFG. Critical habitat was designated for this species on April 13, 2006 (71 FR 19243). Current critical habitat designations do not include the York Creek watershed. CRLF is most common in marshes, streams, lakes, reservoirs, ponds, and other water sources with plant cover. Breeding occurs in deep, slow moving waters with dense, shrubby, or emergent vegetation. Breeding generally occurs from late November through April. Egg masses are attached to emergent vegetation (i.e., Typha sp. or Scirpus sp.) near the water’s surface. Tadpoles require 3.5 to 7 months to attain metamorphosis. Adults take invertebrates and small vertebrates. Larvae are thought to be algal grazers.
Surveys for CRLF have been completed within the project area with negative findings. The nearest known sighting for CRLF is a single recorded occurrence over 5.0 miles to the northeast of the project site in the Pope Valley area (CDFG 2006a). As part of the York Creek Diversion Modification Project carried out by the City of St. Helena in 2004, the potential presence of CRLF was evaluated by California Department of Water Resources (DWR) staff biologists (DWR 2003). Suitable CRLF habitat was identified at the Upper York Creek Reservoir, and focused surveys, under guidance from US Fish and Wildlife Service, were completed in May and June 2001 (DWR 2003). No CRLF were observed during the surveys.
“In 1999, the City of St. Helena hired Ibis Environmental Services to conduct a habitat assessment of the project site. Their report determined that the site contained suitable habitat for California red-legged frogs, noting that the Upper Reservoir contains suitable breeding habitat for red-legged frogs, and York Creek provides suitable dispersal, foraging, and refuge habitat. The US Fish and Wildlife Service had formal surveys for red-legged frogs conducted by DWR in May and June 2001, following established protocols (USFWS 1997). Two daytime and two nighttime protocol surveys found no occurrences of the species (adults, metamorphs or tadpoles) and an abundance of bullfrogs (sub-adults) within the Upper Reservoir area. All bullfrogs were relatively small individuals, suggesting a reproducing population. Bullfrogs, an introduced
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species, predate on red legged frogs. They use the same habitat and eventually displace them.” (Corps 2006b)
The lower reservoir site was not included as part of the biolgocial assessment of the diversion project, and focused surveys for CRLF were not completed at this location. Since the lower reservoir was never evaluated for CRLF habitat and the Service has since issued revised guidance on CRLF site assessments (USFWS 2005), both project sites were re-evaluated for the potential presence of suitable CRLF habitat in April 2006 as part of the routine maintenance activities at the upper reservoir in the summer 2006 (PCI 2006a). CRLF were not observed within the project area during the 2006 field survey.
“Marginally suitable habitat for CRLF was identified at the upper dam site. Habitat elements compatible with CRLF foraging, migration, and aestivation are present within the area. However, suitable breeding habitat was not apparent at the time of the assessment. The entire basin was inundated due to recent rain events. Breeding habitat elements such as favorable emergent vegetation were largely absent.
At the upper dam site, there is a small population of naturalized bullfrogs and several sub-adults [2- 3” Snout to Vent (SV)] were observed. The presence of bullfrogs at the upper site may be discouraging CRLF from establishing in the area. Elimination of bullfrogs in the area and enhancement of the project area could potentially encourage CRLF to colonize the site if they occur in the area. Despite the presence of bullfrogs, CRLF may occur in small numbers within the project area or within close proximity. Previous focused surveys for CRLF were completed along York Creek and included the Upper St. Helena Dam. These surveys occurred in May and June of 2001 by DWR biologists (DWR 2001). No CRLF were observed. The surveyors did note the presence of a population of bullfrogs in the area.
Habitat elements suitable for CRLF survival (basking, foraging, breeding, and aestivation habitat) are present at the lower reservoir site. At the time of the assessment, suitable emergent vegetation for breeding, basking sites, and refuge habitat were observed. No CRLF or bullfrogs were detected at the lower reservoir site. However, bullfrogs are likely to occur there, given the site’s close proximity to the upstream population. The only amphibian species detected at the lower reservoir site was Pacific treefrog (Hyla regilla). Surveys for CRLF by DWR were not completed at the lower reservoir in 2001 (DWR 2001).” (PCI 2006a)
Foothill yellow-legged frog (Rana boylii). The foothill-yellow legged frog is a California Special Concern species. Currently, this species occurs from southern Oregon south to the Salinas River, Monterey County, California,and in isolated patches in the Cascade and Sierra Nevada foothills. The foothill yellow-legged frog is found in or near partly shaded rocky streams from near sea level to 6,300 feet in a variety of habitats. Breeding generally occurs from mid-March to early June after high winter flows have subsided. Egg masses are attached to the downstream side of rock and gravel in shallow, slow, or moderate-sized streams. Tadpoles require three to four months to attain metamorphosis. Adults take aquatic and terrestrial invertebrates, and tadpoles graze along rocky stream bottoms on algae and diatoms. During all seasons, this species is generally found in or within close proximity to streams.
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Electrofishing surveys completed by CDFG in September 2002 yielded one foothill-yellow legged frog within the York Creek watershed (Cox 2002). The single frog was observed between the Upper St. Helena Dam and the lower diversion structure prior to its removal in 2004. There have been no additional sightings reported within the watershed (CDFG 2006a). Foothill yellow-legged frogs were not observed during field surveys; however, suitable habitat is present within York Creek.
Reptiles
Northwestern pond turtle (Emys marmorata marmorata). The northwestern pond turtle is a California Special Concern species and one of two distinct subspecies of the western pond turtle. The western pond turtle occurs from Washington south to Baja, Mexico. The northwestern subspecies occurs from the San Francisco Bay north. The southwestern pond turtle (E. m. pallida) occurs from the San Francisco Bay south. There is a zone of intergradation between the two subspecies throughout the SF Bay and San Joaquin Valley. Pond turtles are most commonly found in or near permanent or semi-permanent water sources in a variety of suitable habitats throughout much of western California. This omnivorous species requires basking sites such as emergent logs, rocks, mud banks, or mats of aquatic vegetation for thermoregulation. Underwater retreats are also required for predator avoidance. Nesting sites of this species have been found some distance, up to 400 meters or more, from aquatic habitat. They have also been found using upland sites for aestivation and overwintering.
According to the CNDDB overlay, there are no recently reported sightings for pond turtles within the project area region (CDFG 2006a). They are known to occur in Conn Creek, a small tributary to the Napa River, several miles downstream of the project site and are also likely to occur along the mainstem Napa River (CDFG 2006a). Suitable habitat for pond turtles occurs within the project area. However, pond turtles were not detected during the field surveys.
Birds
Sharp-shinned hawk (Accipiter striatus). The sharp-shinned hawk is a California Special Concern species. It is a small, fast-flying hawk of mixed woodlands and forested habitats. They forage for small birds through swift and sudden attacks. Sharpies are one of the most common Accipiters in North America. Nesting sites include deciduous trees and conifers, 10 to 60 feet above ground. Average clutch size is 4 to 5 eggs. Breeding occurs from April through August, with peak activity in June and July. Sharp-shinned hawks are a rare summer resident and common throughout fall and winter in Napa County.
Sharp-shinned hawks are known to breed locally and confirmed sightings occur within close proximity to the project area (Berner, et al., 2003). Suitable breeding and foraging habitat for this species occurs within the project area and surrounding habitats.
Tricolored blackbird (Ageblaius tricolor) nesting colony. The tricolored blackbird is listed as a Bird of Conservation Concern by USFWS, a California Special Concern species, and on the Audubon Watch List. The tricolored blackbird is a colonial nester in fields, pastures, and wetlands. Females build a bulky open cup nest in tules, cattails, and to a lesser degree willows and brambles. Breeding occurs from mid-April into late July, and the average clutch size is 3 to 4 eggs. Blackbirds typically are ground foraging birds and tend to do so in large flocks. They
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feed on a variety of insects during the summer months and seeds and grain in the winter. Tricolored blackbirds can be easily confused with red-winged blackbirds in appearance. They are an uncommon summer resident in Napa County, and colonial breeding sites are limited to only a handful of areas.
According to the CNDDB and Napa County breeding bird atlas data, there are no recently reported blackbird sightings within the project area’s region (CDFG 2006a; Berner, et al., 2003). Suitable foraging and marginal breeding habitat occurs at the LYCR. Tricolored blackbirds were not detected during the field surveys.
Yellow warbler (Dendroica petechia brewsteri). The yellow warbler is a California Special Concern species. The yellow warbler is a neotropical migrant songbird that breeds throughout North America. They typically occupy riparian woodlands, montane chaparral, and pine forests. Yellow warblers forage primarily for insects and spiders but will also feed on fruit. Breeding occurs from mid-April into early August. Nesting sites include shrubs and saplings from 2 to 12 feet, and the average clutch size is 3 to 6 eggs. The yellow warbler is a common summer resident in Napa County; however, they have disappeared in recent years from a number of locations within the valley.
Yellow warblers are known to breed locally, and confirmed sightings occur within close proximity to the project area (Berner, et al., 2003). Suitable breeding and foraging habitat for this species occurs within the project area and surrounding habitats.
Yellow-breasted chat (Icteria virens). The yellow-breasted chat is a California Special Concern species and a member of the warbler family (Parulidae). They occupy dense riparian thickets adjacent to stream channels, ponds, and brushy thickets. They forage for insects, spiders, and oftentimes berries from the foliage of low trees and shrubs. Breeding occurs from early May into early June with peak activity in June. Nests sites include dense shrubs along streams and rivers from 2 to 8 feet. Average clutch size is 3 to 4 eggs. Due to a loss of habitat, they have experienced a precipitous decline throughout their range. Chats are an uncommon summer resident and migrant of Napa County, and “anecdotal evidences suggests they have all but vanished from the Napa Valley” (Berner, et al., 2003).
According to the CNDDB and Napa County breeding bird atlas data, there are no recently reported chat sightings within the project area (CDFG 2006a; Berner, et al., 2003). Suitable foraging and marginal breeding habitat occurs at the Upper York Creek Dam and Reservoir and LYCR. Yellow-breasted chats were not detected during the field surveys.
Purple martin (Progne subis). The purple martin is a California Special Concern species and a member of the swallow family (Apodidae). Purple martins frequent riparian and oak woodlands and coniferous and montane forests at upper elevations. They forage over open land and water. Purple martins are cavity nesters and will use primarily natural holes or crevices. Average clutch size is 4 to 5 eggs. Breeding occurs from April into August with peak activity in June. Purple martins are an uncommon migrant and a breeding resident in Napa County.
According to the CNDDB and Napa County breeding bird atlas data, there are no recently reported chat sightings within the project area (CDFG 2006a; Berner, et al., 2003). Suitable
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foraging and breeding habitat occurs within the project area. Purple martins were not detected during the field surveys.
Oak titmouse (Baeolophus inornatus). The oak titmouse is listed on the Audubon Watch List. It is a small, sparrow-sized bird of forested and deciduous habitats where it feeds on seeds and terrestrial invertebrates. The titmouse is a cavity nester and will use both artificial and natural holes or crevices. Average clutch size is 5 to 8 eggs. Oak titmice mate for life and defend territories year-round. The oak titmouse is a year-round resident in Napa County. This species was observed foraging within the project area and is known to breed within the watershed (Berner, et. al. 2003).
Northern spotted owl (Strix occidentalis caurina). The northern spotted owl was listed as threatened on June 26, 1990, by USFWS (55 FR 26114) and is listed on the Audubon Watch List. Critical habitat was designated for this species on January 15, 1992 (57 FR 1796). Current critical habitat designations do not include Napa County.
The spotted owl is an uncommon permanent resident of dense forest habitats in northern California and oak and oak-conifer habitats in southern California. This nocturnal species requires dense, multi-layered canopy cover for roosting sites. Spotted owls feed upon a variety of small mammals, birds, and large arthropods. Nest sites include tree or snag cavities or broken tops of large trees. The typical breeding period lasts from early March through June rearing 2 young per season. A pair of owls may utilize the same breeding site for 5 to 10 years; however, they may not breed every year. The spotted owl has experienced a population decline due to the loss and degradation of existing mature and old growth forests. They are a year- round resident of Napa County and are known to occur within the York Creek watershed (Berner, et. al. 2003).
“A pair of Northern Spotted Owls in the upper York Creek watershed maintains a territory approximately one mile upstream from York Creek Dam. The owls have been monitored annually since 1995 by biological consultant Mr. Ted Wooster. The project site is located within the 1.3-mile radius the California Department of Forestry considers to be the limit of their foraging area. However, project activities will occur at least 1 to 1.5 miles away. In order to avoid impacts to northern spotted owls, construction shall be carried out only during the day. Lights will not be used. Breeding habitat should not be affected because the project is more than 0.7 mile from the activity center.” (Corps 2006b)
Mammals
Pallid bat (Antrozous pallidus). The pallid bat is a California Special Concern species. They occupy grassland, shrubland, woodland, and forest habitats at low elevations in California. Pallid bats can most commonly be found in open, dry habitats with suitable rocky areas for roosting. This species can also be found roosting in caves, crevices, mines, hollow trees, and buildings during the day. Night roosts generally consist of more open areas such as porches and open buildings. This species feeds chiefly on a variety of arachnids and insects. The pallid bat is a year-round resident throughout most of its range. During the non-breeding season, both sexes may be found roosting in groups of 20 or more individuals. Young are born from April to July. As with many bat species, pallid bat is extremely sensitive to roosting site disturbance.
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According to the CNDDB, there are no recently reported pallid bat sightings within the project area (CDFG 2006a). Suitable habitat occurs within the project area. Pallid bats may forage over the sites and utilize the larger trees as temporary foraging, daytime, or night roosts. Pallid bats were not observed during the field surveys; however, focused bats surveys were not completed.
Townsend’s western big-eared bat (Corynorhinus townsendii townsendii). The Townsend’s western big-eared bat is a California Special Concern species. They are found throughout much of California, with the exception of subalpine and alpine communities, most commonly in mesic habitats. This species is most active in late evening when they can be found foraging for small moths, beetles, and other soft-bodied insects. Roosting, maternity, and hibernacula sites include limestone caves, lava tubes, mines, tunnels, or human-made structures and buildings. Hibernation generally occurs from October to April, and young are born from May to June, peaking in late May. This species is extremely sensitive to disturbance at roosting sites. Populations of big-eared bats have declined precipitously in California.
According to the CNDDB, there are no recently reported big-eared bat sightings within the project area (CDFG 2006a). Suitable habitat occurs within the project area. Townsend’s western big-eared bat may forage over the sites. Big-eared bats were not observed during the field surveys; however, focused bats surveys were not completed.
Fish
Steelhead - Central California Coast (Oncorhynchus mykiss) Status. There are six distinct population segments (DPS) of steelhead within California, including the Central California Coast (CCC) DPS. NOAA’s National Marine Fisheries Service listed CCC steelhead as a threatened species on August 18, 1997 (62 FR 43937), and its threatened status was reaffirmed on January 5, 2006 (71 FR 834). This population occurs below natural and manmade impassable barriers in California streams from the Russian River (inclusive) to Aptos Creek (inclusive), and the drainages of San Francisco, San Pablo, and Suisun Bays, excluding the Sacramento-San Joaquin River Basin, as well as two propagated stocks (NOAA Fisheries Service 2006). Critical habitat for CCC steelhead was designated on September 2, 2005 (70 FR 52488) and includes the Napa River and its tributaries (including York Creek).
Life History. Steelhead are anadromous salmonids, meaning they spawn in freshwater and mature in the ocean. Adults spend one to four years at sea before returning to their natal streams to spawn. Unlike other salmonids, steelhead may spawn as many as four times. Adult steelhead spawn from December through April in cool, clear, well-oxygenated streams with pea to apple-sized gravel, 1.3 to 11.7 cm. Eggs are deposited in a depression called a redd, usually at the head of riffle. Eggs hatch between 19 and 80 days, depending on stream temperatures. Alevins, newly hatched fish, remain in the gravel for 2 to 3 weeks until their yolk sac is absorbed. They then emerge from the gravel as fry. The young fish remain in edgewater habitats often in small schools. As they grow larger, they move out into the stream channel into pool and riffle habitats. Juveniles require cool stream flows to transport drifting insects for feeding and cover in the form of undercut banks, woody debris, boulders, and deep pools to escape predation and high flows. After spending up to two years in freshwater, steelhead migrate downstream to the ocean as smolts. Steelhead that remain in freshwater streams are
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called rainbow trout. Unlike steelhead, rainbow trout are not protected under the federal Endangered Species Act.
Environmental requirements for steelhead vary by season and life stage. Optimal water temperatures for steelhead range from 10 to 15°C, with an upper lethal limit of 20°C. Rearing salmonids require a high level of dissolved oxygen, at least 80%, with a minimum temporary reduction no lower than 5.0 mg/l. Deposited and suspended sediment plays a significant role in their ability to successfully spawn and rear. Optimal upstream migration water velocities range from 40 to 90 cm/s and a minimum stream depth of 13 cm.
Population Estimates
“Napa River steelhead populations have been greatly reduced from historical levels. It is estimated that the Napa River watershed supported a population of approximately 8,000 adult steelhead as recently as 100 years ago. The current steelhead population is unknown due to a lack of quantitative data. Recent basin wide surveys estimate the population to be between 200 and 1,000 adult steelhead (Stillwater Sciences, 2002; EcoTrust, 2001). NOAA Fisheries listed steelhead as a threatened species in Napa County in August 1997. Spawning adult steelhead are still documented each year by landowners and agencies, and most tributaries to the Napa River appear to be well seeded with juveniles (EcoTrust, 2001). Despite reduced populations, the Napa River watershed is considered one of the most significant anadromous fish streams within San Francisco Bay (Leidy et al., 2005) (RCD, 2005).” (Corps 2006b)
York Creek is known to support Central California Coast steelhead. Habitat surveys by NOAA Fisheries Service and CDFG, completed during the summers of 2000 and 2002, found abundant steelhead downstream of the dam and resident rainbow trout above the dam (Corps 2006b). Snorkel surveys conducted in the summer of 2004, by Napa County RCD, found moderate densities of juvenile steelhead and larger resident rainbow trout in most reaches (Corps 2006b). In summer 2005, as part of the York Creek Diversion Modification project, a 120-foot reach of stream channel was dewatered to facilitate construction. Sixty-four steelhead were captured within the work area and relocated (PCI 2004). In summer 2006, the Upper York Creek Reservoir was dewatered to facilitate routine maintenance and sediment removal above the dam. In a 500-foot reach of stream channel, 12 rainbow trout were captured and released upstream (PCI 2006b). There are no reports of stocking trout in York Creek by CDFG (Corps 2006b).
Based on habitat data collected as part of the Central Napa River Watershed Plan by Napa County RCD, York Creek has been identified as one of the “most significant spawning and rearing streams for steelhead within the Napa Basin” (NCRCD 2005). The upper reaches of the watershed, above the dam, “offer excellent spawning and rearing habitat, and creating access to these areas will greatly benefit the overall steelhead population” (NCRCD 2005). As a result of dam removal, approximately 1.7 miles (8,855 feet) of aquatic habitat could become available to CCC steelhead. Newly accessible steelhead habitat would include 0.30 acres of pool, 0.33 acres of flatwater, and 0.85 acres of riffle habitat, totaling 1.5 acres. This reach could potentially support between 825 and 1,810 juvenile steelhead annually, under current habitat conditions (Corps 2006b).
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Chinook salmon (Oncorhynchus tshawutscha). Within California, there are several distinct population segments of Chinook salmon with their own listing status (Table 7). Chinook salmon are the largest member of the Oncorhynchus genus and can reach up to 30 pounds. They typically spawn in large coastal streams and rivers. Locally, Chinook salmon enter river systems in late summer through winter with peak spawning occurring in November and December. Spawning occurs in fast-moving, shallow riffles with clean, loose gravel. Chinook salmon die after spawning. Shortly after emerging from the gravel (after 30 to 150 days), young Chinook salmon begin the downstream migration to the ocean where they spend two to fours years before returning to freshwater. Chinook salmon populations have declined dramatically from historic levels.
Chinook salmon are known to occur and successfully spawn in the Napa River. Napa River Chinook salmon are considered to be strays from the Central Valley (Jones & Stokes 2006). Chinook are not known to occur in York Creek. This species is typically confined to the mainstem Napa River and larger tributaries; they are not typically found in small drainages. The likelihood of occurrence within York Creek is low.
Invertebrates
California freshwater shrimp (Syncaris pacifica). California freshwater shrimp is federally and state-listed as endangered. It is a small, 10-legged crustacean occurring in low-elevation and gradient (less than 1%) perennial streams in Marin, Sonoma, and Napa counties. They occur in shallow pools away from the main current where they feed primarily on detritus and, to a lesser extent, on decomposing vegetation, dead fish, and invertebrates. Most shrimp appear opaque to nearly transparent with colored flecks across their bodies. Females can appear dark brown to purple under certain conditions. Breeding occurs in the autumn, but young do not hatch until the following May or early June. After breeding, female shrimp carry the fertilized eggs attached to their abdominal swimming legs throughout the winter. The freshwater shrimp has been extirpated from many streams and continues to be threatened by introduced predators, pollution, and habitat loss.
Historically, California freshwater shrimp were known to occur along the mainstem Napa River in the upper watershed (USFWS 1998). Recent sighting are restricted to Garnett Creek, an upstream tributary to the Napa River (USFWS 1998). Suitable habitat in the form of undercut banks, refuge habitat, and rootwads extending into the channel are largely absent from the project area. No shrimp were observed during the fish surveys completed in September 2006, and the likelihood of occurrence within the project area is low. As part of the York Creek Diversion Modification Project carried out by the City of St. Helena in 2004, the potential presence of California freshwater shrimp within lower York Creek was evaluated by California Department of Fish and Game (DWR 2003).
“Bill Cox, Fishery Biologist for DFG and recognized expert on freshwater shrimp, surveyed York Creek for fishes in September 2000 (DFG 2000), and assessed the habitat suitability for California freshwater shrimp in the vicinity of York Creek Dam. In his assessment, Mr. Cox states that the “stream was much too shallow, had much too high a gradient, and had essentially no undercut banks or overhanging vegetation to provide any habitat for the shrimp” (B. Cox, pers. comm. 2001). The results of Mr. Cox’s habitat assessment were reported to USFWS (DWR 2001). The lower section of York Creek
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where stream gradients might be more suitable for the species is characterized by intermittent flow, going dry during the summer months, and therefore does not provide suitable habitat for the species.” (DWR 2003)
3.3.2 Standards Appendix G of the CEQA Guidelines (as revised) indicates that a project would have a significant effect on the environment if it would:
• Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites;
• Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special-status species in local or regional plans, policies, or regulations, or by the CDFG or USFWS;
• Have a substantial adverse effect on federally protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means;
• Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations, or by the CDFG or USFWS;
• Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance; or
• Conflict with the provisions of an adopted habitat conservation plan, natural community conservation plan, or other approved local, regional, or state habitat conservation plan.
In addition to the above, CDFG and USFWS guidelines consider a project to have a significant impact if it were to cause a change in species composition or result in the measurable degradation of sensitive habitats such as wetlands, oak woodlands, and/or perennial grasslands. Impacts would also be considered significant if proposed activities are subject to regulation by U.S. Army Corps of Engineers under Section 404 of the federal Clean Water Act, the Regional Water Quality Control Board under Section 401 of the federal Clean Water Act and the state’s Porter-Cologne Act, and the California Department of Fish and Game under Section 1600, et seq., of the Fish and Game Code.
For the purposes of this EIR, the determination of significance is based on the above-mentioned guidelines and policies set forth by the County’s General Plan and other documents as referenced in the DEIR. Environmental impacts associated with the proposed project are discussed below. Impacts are classified as significant, potentially significant, adverse but less than significant, or less than significant. Mitigation measures are provided whenever possible to avoid or reduce the impact to less than significant.
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3.3.3 No Project Alternative: Impacts and Mitigation Measures Under the No Project Alternative, Upper St. Helena Dam would not be altered from its current configuration, and no ecosystem restoration measures would be implemented. The dam would continue to act as an unnatural barrier, and fish passage would not be restored. Maintenance dredging would need to occur on a regular basis to offset the continued deposition of sediment behind the dam. Under the No Project Alternative, disposal and/or reuse sites would include Lower York Creek Reservoir, Spring Mountain Vineyard, and/or Clover Flat landfill with quantities to be determined.
Impact BIO-NP1: Upper St. Helena Dam would continue to act as an unnatural migration barrier to fish and other aquatic species. (Significant and long-term)
Under the No Project Alternative, the dam would remain and continue to act as an unnatural barrier to upstream and downstream migration of fish and other aquatic species. Central California Coast steelhead would continue to be confined to habitats downstream of the dam, and resident fish (i.e., prickly sculpin) and other aquatic species (i.e., foothill yellow-legged frog) would continue to be isolated from neighboring populations. Approximately 1.7 miles of aquatic habitat would remain inaccessible and ecologically disconnected from downstream habitats.
Mitigation BIO-NP1: On-going impacts to migration from the presence of Upper St. Helena Dam are considered significant and unavoidable. Mitigation is not applicable.
Significance after Mitigation. Significant and unavoidable.
Impact BIO-NP2: Upper St. Helena Dam and Reservoir would continue to disrupt the natural transport of materials and organisms, reducing their availability for downstream habitat and food and adversely affecting aquatic species and habitat. (Significant and long-term)
Under the No Project Alternative, the natural transport of materials and migration of fish and other aquatic species would continue to be disrupted. Currently, the dam acts as a retention structure slowing the flow of silt, gravel, woody debris, and other materials and organisms downstream. This limits their use for downstream habitat and food and adversely affects aquatic species and habitat occurring within the lower reaches of the watershed.
Mitigation BIO-NP2: On-going impacts to natural transport functions from the presence of Upper St. Helena Dam are considered significant and unavoidable. Mitigation is not applicable.
Significance after Mitigation. Significant and unavoidable.
Impact BIO-NP3: Future maintenance dredging could result in temporary, short-term downstream sediment releases, kills of fish and other aquatic species, and destruction of habitat downstream of the dam. (Potentially significant and short-term)
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To offset the continued deposition of sediment behind the dam and filling of the reservoir, maintenance dredging would need to occur under the No Project Alterative. Approximately 28,000 cubic yards of sediment are trapped behind the reservoir, and an additional 1,000 to 1,500 cubic yards are deposited annually (Corps 2006a). Dredging would need to be performed annually or at 5 to 10-year intervals, as has occurred in the past.
Since 1965, four documented sediment discharges have occurred downstream during routine maintenance activities (Corps 2006a). In 1992, the California Department of Fish and Game documented an accidental sediment discharge during routine maintenance. The total distance of impact was 2.5 to 3.0 miles downstream of the dam. Deposition varied with heavy deposits (up to 18 inches) just below the dam to 0.5 miles downstream gradually thinning out to a light covering of fine silt near the confluence with the Napa River (Corps 2006a). During future maintenance dredging, there is a significant potential for sediment to become mobilized. This could result in fish and aquatic species kills and destruction of habitat downstream of the dam.
Mitigation BIO-NP3: To reduce the potential for destructive sediment releases downstream of the dam during maintenance dredging, the City of St. Helena shall implement the following measures:
• To ensure potential impacts to downstream aquatic species and all other sensitive biological resources are avoided or minimized, a detailed dewatering and species protection plan will be developed and implemented by a NOAA’s Fisheries Service and CDFG-approved biologist. • Maintenance dredging will be completed during summer low flow conditions between June 15 and October 15. • Work will be performed in isolation from the flowing stream. Coffer dams or other approved water diversion structures will be constructed at the upstream and downstream ends of the project site to isolate the work area. The water will be diverted through a suitably sized pipe from upstream of the upstream coffer dam and discharged downstream of the downstream coffer. Coffer dams will be constructed of a non- erodible material that does not contain soil or fine sediment. • Erosion control measures will be utilized throughout all phases of construction where sediment runoff from exposed slopes threatens to enter the water. At no time will silt laden runoff be allowed to enter the stream or be directed to where it may enter the stream. • Dredged material will be disposed of at an alterative site with proper erosion control measures in place. • Throughout construction, a qualified biologist will monitor to ensure water quality standards are being met and sediment is not entering the watercourse. • A pre-construction training session will be provided for construction crew members by the qualified biologist. The training will include a discussion of the sensitive biological resources within the project area and the potential impacts of accidental sediment releases. This will include a discussion of species habitat, protection measures to insure species are not impacted by project activities, and project boundaries.
Significance after Mitigation. Less than significant.
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Impact BIO-NP4: Maintenance dredging could result in direct disturbance, displacement, and/or mortality to non-listed aquatic species. (Adverse but less than significant and short-term)
To facilitate maintenance dredging activities, dewatering of the work area (Upper York Creek Reservoir) would need to occur. During dewatering, the entire project reach would need to be isolated from flowing water, and common aquatic species (i.e., prickly sculpin, rainbow trout) would be relocated upstream of the project site. While these impacts are not considered significant under CEQA guidelines, such actions could result in incidental take of non-listed aquatic species through direct disturbance, displacement, and/or mortality, resulting in an adverse effect on the local aquatic community.
Mitigation BIO-NP4: Adverse but less than significant impacts do not require mitigation; however, to avoid and/or reduce the potential for direct disturbance, displacement, and/or mortality to aquatic species, the City of St. Helena shall implement the following measures:
• A detailed dewatering and species protection plan will be developed and implemented by a NOAA’s Fisheries Service and CDFG-approved biologist. • Aquatic species will be relocated by the qualified biologist prior to commencing project construction. The site will also be swept periodically during construction to ensure no aquatic species have moved into the area. • A qualified biologist will be on site during construction of water diversion structures and decommissioning. • Work will be performed in isolation from the flowing stream. Coffer dams or other approved water diversion structures will be constructed at the upstream and downstream ends of the project site to isolate the work area. The water will be diverted through a suitably sized pipe from upstream of the upstream coffer dam and discharged downstream of the downstream coffer. Coffer dams will be constructed of a non- erodible material which does not contain soil or fine sediment. The stream will be returned to its natural flow and bed condition upon project completion. • An approved screen pump intake will be used to divert water. Pumps will be screened in accordance with Juvenile Fish Screen Criteria for Pump Intakes developed by NOAA’s National Marine Fisheries Service and will consist of 3/32-inch screen mesh (NOAA Fisheries Service 1996). • Proper erosion control and other water quality Best Management Practices (BMPs) will be implemented to avoid sedimentation and disturbance into the creek. • A pre-construction training session will be provided for construction crew members by the qualified biologist. The training will include a discussion of the sensitive biological resources within the project area and aquatic species habitat, protection measures to insure aquatic species are not impacted by project activities, and project boundaries. • Prior to maintenance activities, consultation with California Department of Fish and Game shall occur and authorization obtained to relocate aquatic species.
Significance after Mitigation. Less than significant.
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Impact BIO-NP5: Maintenance dredging could result in incidental take of California red-legged frog (Rana aurora draytonii) and foothill yellow-legged frog (Rana boylii). (Potentially significant and short-term)
Maintenance dredging activities have the potential to result in incidental take of California red- legged frog (CRLF) and/or foothill yellow-legged frog (FYLF) through direct disturbance, mortality, and/or habitat modification.
Mitigation BIO-NP5: To avoid impacts to California red-legged and foothill-yellow legged frogs during construction, the City of St. Helena shall implement the following measures: • A preconstruction survey for CRLF and FYLF will occur prior to beginning work, and work will only occur in areas that have been surveyed. • All construction crews will be trained by a qualified biologist on the status, life history characteristics, and avoidance measures for CRLF and FYLF. • Earthwork will be completed during the dry season when winter rainwater has receded, the project site has been dewatered, and frogs are likely to have moved to wetter habitat. • If CRLF and/or FYLF are encountered during construction, USFWS and CDFG will be contacted for guidance, and/or they will be relocated by a permitted biologist. • During construction, a qualified biologist should make frequent visits to the project area to ensure no CRLF, FYLF, or other species have entered the work area and are being impacted by construction activities. • Prior to maintenance activities, consultation with USFWS and CDFG shall occur and authorization obtained to relocate frogs during construction activities.
Significance after Mitigation. Less than significant.
Impact BIO-NP6: Maintenance dredging could result in direct disturbance, displacement, and/or mortality to special-status and common bat species. (Potentially significant and short-term)
Maintenance dredging activities have the potential to result in disturbance, displacement, and/or mortality to special-status and common bat species as a result of vegetation removal. Two special-status bat species, pallid bat and Townsend’s big-eared bat, have low to moderate potential to occur within the project area, and additional bat species may utilize the project area for foraging and roosting as well. Direct impacts (i.e. removal of trees supporting roosts) would adversely affect any of these bat species and be considered significant. Construction activities are not likely to disrupt the foraging behavior of bats as they are mostly nocturnal, and work will be restricted to daylight hours.
Mitigation BIO-NP6: To avoid impacts to special-status and common bat species during construction, the City of St. Helena shall implement the following measures: • Prior to commencing work, a qualified biologist will survey the site for bat roosts. If occupied roosting habitat is identified, removal of roost trees would not be allowed until the roost is unoccupied.
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• All construction crews will be trained by a qualified biologist on the status, life history characteristics, and avoidance measures for bats. • Construction will be limited to daylight hours so as to not interfere with the foraging abilities of bats.
Significance after Mitigation. Less than significant.
Impact BIO-NP7: Maintenance dredging could result in both direct and indirect impacts to nesting birds as a result of nest destruction, mortality, and/or disturbance. (Potentially significant and short- term)
To facilitate maintenance dredging activities, removal of established vegetation within the reservoir and along the access route would need to occur. Such actions could result in direct impacts to breeding birds and their offspring through nest destruction and mortality. Indirect impacts are likely to occur as a result of increased human presence and noise.
Under the Migratory Bird Treaty Act (MBTA), it is unlawful to take, kill, and/or possess migratory birds at any time or in any manner, unless the appropriate permits are obtained. Protections extend to active nests, eggs, and young birds still in the nest. Most bird species, with a few specific exceptions, are protected under this act. Construction activities during the breeding period, typically mid-March to mid-August in this region (RHJV 2004), could result in losses to these and other native wildlife species.
Mitigation BIO-NP7: To avoid potential losses to nesting migratory birds, construction activities should occur outside of the critical breeding period. If activities must occur during the normal breeding season, work areas shall be surveyed by a qualified biologist prior to commencing. If active nests or behavior indicative of nesting birds are encountered, those areas plus a 50-foot buffer area for small songbirds and 250-foot buffer for larger birds (i.e., owls, raptors) designated by the biologist shall be avoided until the nests have been vacated. On-going construction monitoring will occur to monitor nesting activity within the project area. If state and/or federally-listed species (i.e., northern spotted owl) are found breeding within the project site, activities will be halted and consultation with the Corps and USFWS will occur, and the conditions of these agreements shall serve as additional provisions.
Significance after Mitigation. Less than significant.
Impact BIO-NP8: Future maintenance dredging could result in direct disturbance, displacement, and/or mortality to terrestrial wildlife species. (Adverse but less than significant and short-term)
To facilitate maintenance dredging activities, aquatic habitat would be modified and/or destroyed, potentially resulting in disturbance, displacement, or mortality to terrestrial wildlife species (i.e., reptiles, amphibians, and mammals). While these impacts are not considered significant, they would have an adverse effect on local wildlife communities. Mobile wildlife species would be displaced as part of the initial construction activities, and these species would likely colonize adjacent habitats. Direct mortality could result to non-mobile species.
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Mitigation BIO-NP8: Adverse but less than significant impacts do not require mitigation; however, to avoid and/or reduce the potential for direct disturbance, displacement, and/or mortality to common wildlife species (i.e., reptiles, amphibians, and mammals), the City of St. Helena shall implement protective measures. A preconstruction survey (on the day preceding work and/or ahead of the construction crew) shall be performed prior to disturbance of the site and stream channel to ensure that no terrestrial species are occupying the site. If terrestrial species are observed within the project site or immediate surroundings, these areas shall be avoided until the animal(s) has (have) vacated the area, and/or the animal(s) shall be relocated out of the project area by a qualified biologist. In addition, the site will be surveyed periodically during construction to ensure that no terrestrial species are being impacted by construction activities.
Significance after Mitigation. Less than significant.
Impact BIO-NP9: Disposal of materials at Lower York Creek Reservoir and alteration of York Creek could result in the disturbance/loss of jurisdictional wetlands and/or other waters of the U.S. (Potentially significant and long-term)
Potential jurisdictional wetlands and other waters of the U.S. were identified at LYCR based on the presence of at least one wetland parameter and presence of an Ordinary High Water Mark. Utilizing the LYCR as a disposal and/or reuse site could result in filling or altering such resources. In addition, York Creek is a perennial stream and is considered an “other waters of the U.S.” These areas are potentially subject to the jurisdiction of the Corps under Section 404 of the Clean Water Act, San Francisco Bay Regional Water Quality Control Board under Section 401 of the federal Clean Water Act or Porter Cologne, and California Department of Fish and Game under Section 1600 of the California Fish and Game Code. Filling or altering potential jurisdictional wetlands and/or other waters would result in a significant impact.
Mitigation BIO-NP9: If it is infeasible to avoid filling or altering potentially jurisdictional wetlands and/or other waters of the U.S. during construction, the City of St. Helena shall implement the following measures:
• Prior to construction, the City of St. Helena shall obtain appropriate state and federal permits for impacts to wetlands and/or other waters of the U.S. This will include, but is not limited to, obtaining permits from the U.S. Army Corps of Engineers, San Francisco Bay Regional Water Quality Control Board, and/or California Department of Fish and Game. The conditions of these agreements shall serve as additional provisions. • The City of St. Helena shall compensate for the loss of jurisdictional wetlands and/or other waters of the U.S. at a ratio of 1:1 (or as agreed upon by the permitting agencies) within the project site, or at a ratio of 2:1 (or as agreed upon by the permitting agencies) off site or for out-of-kind compensation (mitigating impacts on one habitat type by creating, restoring, or enhancing another habitat type). The restoration effort shall require implementation of a 5-year monitoring program with applicable performance standards, including but not limited to, establishing 80% survival rate of restoration
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plantings, absence of invasive plant species, absence of erosion features, and presence of a functioning, self-sustainable wetland system.
Significance after Mitigation. Less than significant.
Impact BIO-NP10: Maintenance dredging activities could result in damage and/or mortality to special-status plant species if they are present within the work area. (Potentially significant and short-term)
No summer blooming special-status plant species were observed within the work area during a survey conducted in June 2006. A plant survey will be conducted in spring 2007 to determine whether spring blooming special-status plants are present. If no special-status plants are observed during the spring 2007 survey, special-status plants can be considered absent18 from the work area, and, therefore, adverse impacts are not anticipated from maintenance dredging activities. If special-status plants are found during the survey, mitigation measures will be implemented to reduce or eliminate impacts to the population.
Mitigation BIO-NP10: If special-status plants are found during the spring 2007 survey, the City of St. Helena shall implement the following measures:
• The special-status plant population will be flagged on the ground, mapped onto project basemaps, and the number of individuals quantified. • If feasible, the population will be avoided during maintenance dredging activities. The population—along with a buffer to protect the population from direct and indirect impacts, the width of which should be based on species requirements, proximity to the work area, and other site specific factors—will be fenced with high visibility orange fencing to prevent entry by construction personnel or equipment. All construction personnel will be trained by a qualified biologist on the location and extent of the special-status plant population and the importance of avoidance. • If direct impacts are unavoidable, adverse impacts to the population from maintenance dredging will be quantified, and a mitigation and monitoring plan will be developed in consultation with the CDFG and/or the USFWS (depending on the listing status of the species to be impacted) that may include avoidance measures, soil stockpiling, seed collection and propagation, and/or other measures to minimize the adverse impacts to the population.
Significance after Mitigation. Less than significant.
Impact BIO-NP11: Native wetland and riparian vegetation around the upper and lower reservoirs will be impacted during maintenance dredging, resulting in a temporary loss of habitat and increasing the likelihood of establishment of invasive non-native, disturbance-adapted plant
18 Even if species are not anticipated to occur, if any special-status plant or wildlife species were encountered during project construction, the project would be required to comply with CEQA and the state and federal Endangered Species Acts.
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species, which could inhibit native vegetation establishment and cause a permanent loss of biotic functions and values. (Potentially significant and short-term)
To facilitate maintenance dredging activities, removal of established native riparian vegetation—potentially subject to regulatory jurisdiction by the U.S. Army Corps of Engineers, San Francisco Bay Regional Water Quality Control Board, and California Department of Fish and Game—within and adjacent to the reservoir would need to occur. Vegetation removal will result in a temporary loss of biotic functions and values, including plant and wildlife habitat, stream shading, erosion control, and species diversity. In addition, decreased ground shading and exposure of bare mineral soil caused by vegetation removal provide recruitment opportunities for invasive non-native, disturbance-adapted plant species. If not controlled, invasive non-native species could inhibit natural vegetation recovery, causing a permanent loss of biotic functions and values.
Mitigation BIO-NP11: To reduce the adverse impacts related to native riparian vegetation removal during maintenance dredging, the City of St. Helena shall implement the following measures:
• Prior to dredging, a mitigation plan will be prepared by a qualified biologist as part of the required regulatory agency permits discussed in mitigation measure Mitigation BIO–NP9. All jurisdictional areas subject to vegetation removal will be re-vegetated with equivalent native species at a ratio of 1:1 (or as agreed upon by the permitting agencies). The mitigation plan will require implementation of a 5-year monitoring program with applicable performance standards, including but not limited to, establishing 80% survival rate of restoration plantings, control of invasive plant species, and contingency measures to ensure planting success. • All propagules used for mitigation plantings will be obtained from local nursery stock, if available. Willow cuttings will be obtained from on site prior to vegetation removal. • Only certified, weed-free materials dominated by native species will be used for erosion control. • An invasive plant control program will be included as part of the mitigation plan. The invasive plant control program will describe species to be targeted for removal (i.e., those categorized as High or Moderate by the California Invasive Plant Council (2006)), control methods to be used (i.e. pulling, digging, or other approved exotic plant control methods), and performance standards to ensure success.
Significance after Mitigation. Less than significant.
Impact BIO-NP12: Native upland vegetation will be impacted during maintenance dredging activities. Removal of vegetation can result in a temporary loss of plant and wildlife habitat, increased erosion, and establishment of invasive non-native, disturbance-adapted plant species, which could inhibit native vegetation establishment and result in a permanent loss of biotic functions and values. (Adverse but less than significant and short-term)
Native and non-native upland vegetation will be removed from the access road and other upland areas during maintenance dredging operations. This includes mixed evergreen forest and redwood forest at Upper York Creek Reservoir and foothill pine-oak woodland around
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Lower York Creek Reservoir. In addition, non-native upland vegetation, including ruderal vegetation around Upper York Creek Reservoir, ruderal and non-native grassland around Lower York Creek Reservoir, and ruderal vegetation at Spring Mountain Vineyard, will be impacted during maintenance activities.
Mitigation BIO-NP12: Adverse but less than significant impacts do not require mitigation; however, to avoid and/or reduce the potential for adverse impact to vegetation, the City of St. Helena shall implement protective measures: • Vegetation removal will be minimized to the maximum extent practicable during all work activities. Grading limits will be clearly flagged to minimize disturbance from construction equipment. • Upland native trees greater than 12 inches diameter at breast height that are removed as a result of maintenance dredging activities will be replaced at a minimum 1:1 ratio with equivalent native species. All propagules used for native plantings will be obtained from local nursery stock, if available. • All disturbed areas will be revegetated with native plantings and/or a native seed mix as soon as practicable to minimize erosion and recruitment of invasive non-native plant species. Best Management Practices that avoid dispersal of invasive non-native plants will be used, including using only certified, weed-free materials dominated by native species for erosion control and revegetation. • Any tree removal associated with maintenance dredging will comply with the City of St. Helena’s Tree Ordinance.
Significance after Mitigation. Less than significant.
3.3.4 Preferred Alternative - Small Notch: Impacts and Mitigation Measures The Small Notch Alternative is designed to restore the ecological connectivity between habitats upstream and downstream of the dam and provide for a natural sediment transport system. Central California Coast (CCC) steelhead migration would be restored to 100% effectiveness19. This alternative allows for the removal of 95% of sediment behind the dam reducing the threat of future sediment releases and removal of 72% of the actual dam material. A 23-foot wide natural stream channel would be restored, and 2.0 acres of streambank (0.4 acres), terrace (0.5 acres), and riparian zone (1.1 acres) would be revegetated. Approximately 1.7 miles (8,855 feet) of aquatic habitat would become available to CCC steelhead including 0.30 acres of pool, 0.33 acres of flatwater, and 0.85 acres of riffle habitat, totaling 1.5 acres. This reach could potentially support between 825 and 1,810 juvenile steelhead annually under current habitat conditions (Corps 2006a).
The existing spillway adjacent to Spring Mountain Road would remain intact and be filled with sediment from the project site. This provides the most geologically stable alternative that allows for the restoration of York Creek’s natural hydrologic functions. Notching the dam would generate approximately 40,000 cubic yards of materials (Corps 2006a). Materials not utilized during ecosystem restoration will be reused or disposed of at LYCR, SMV, and/or Clover Flat Landfill. Materials deposited at LYCR would impact 0.22 acres of freshwater wetland habitat,
19 100% effectiveness means unobstructed fish passage upstream and downstream of the project site.
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1.2 acres of open water habitat, and less than 0.1 acres of foothill pine-oak woodland, non-native grassland, and ruderal habitat combined. Acres of impact for freshwater wetland and open water are based on the preliminary delineation. This delineation is subject to verification by the Corps and may change as a result. 3.76 acres of ruderal habitat would be impacted at SMV. Significant biological impacts for the disposal of materials at Clover Flat Landfill are not anticipated; therefore, they are not addressed in this section.
Impact BIO-PA1: Construction activities could result in temporary short-term downstream sediment releases, kills of fish and other aquatic species, and destruction of habitat downstream of the dam. (Potentially significant and short-term)
Protocols for dewatering the project site during construction will follow measures described in Impact BIO-NP3.
Mitigation BIO-PA1: To reduce the potential for destructive sediment releases downstream of the dam during construction, the City of St. Helena shall implement the measures outlined in Mitigation BIO- NP3.
Significance after Mitigation. Less than significant.
Impact BIO-PA2: Construction activities could result in direct disturbance, displacement, and/or mortality to aquatic species. (Potentially significant and short-term)
To facilitate construction, dewatering of the work area would need to occur. During dewatering, the entire project reach, including habitats downstream of the dam, would need to be isolated from flowing water, and aquatic species (i.e., prickly sculpin, rainbow trout, steelhead) would be relocated upstream of the project site. Such actions could result in incidental take through direct disturbance, displacement, and/or mortality and could have an adverse short-term effect on the local aquatic community.
Mitigation BIO-PA2: To reduce the potential for direct disturbance, displacement, and/or mortality to aquatic species, the City of St. Helena shall implement the measures outlined in Mitigation BIO-NP4. In addition, prior to construction, consultation with NOAA Fisheries Service and CDFG regarding potential impacts to listed steelhead shall occur, and incidental take permit(s) obtained for relocation activities.
Significance after Mitigation. Less than significant.
Impact BIO-PA3: Construction activities could result in incidental take of California red-legged frog (Rana aurora draytonii) and foothill yellow-legged frog (Rana boylii). (Potentially significant and short-term)
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Construction activities have the potential to result in incidental take of California red-legged frog (CRLF) and/or foothill yellow-legged frog (FYLF) through direct disturbance, mortality, and/or habitat modification. In the long-term, habitat conditions are likely to improve through restoration of the natural stream channel in York Creek at the upper reservoir and dam and restoration and/or creation of wetland habitat at LYCR.
Mitigation BIO-PA3: To reduce the potential for impacts to CRLF and FYLF during construction, the City of St. Helena shall implement the measures outlined in Mitigation BIO-NP5.
Significance after Mitigation. Less than significant.
Impact BIO-PA4: Construction activities could result in direct disturbance, displacement, and/or mortality to special-status and common bat species. (Potentially significant and short-term)
Construction activities have the potential to result in disturbance, displacement, and/or mortality to special-status and common bat species as a result of vegetation removal. Two special-status bat species, pallid bat and Townsend’s big-eared bat, have low to moderate potential to occur within the project area, and additional bat species may utilize the project area for foraging and roosting as well. Direct impacts (i.e. removal of trees supporting roosts) would adversely affect any of these bat species and be considered significant. Construction activities are not likely to disrupt the foraging behavior of bats as they are mostly nocturnal, and work will be restricted to daylight hours.
Mitigation BIO-PA4: To avoid impacts to special-status and common bat species during construction, the City of St. Helena shall implement the measures outlined in Mitigation BIO-NP6.
Significance after Mitigation. Less than significant.
Impact BIO-PA5: Construction activities could result in both direct and indirect impacts to nesting birds as a result of nest destruction, mortality, and/or disturbance. (Potentially significant and short- term)
To facilitate construction activities, removal of established vegetation within the work area, along access routes, and possibly at LYCR would need to occur. Such actions could result in direct impacts to breeding birds and their offspring through nest destruction and mortality. Indirect impacts are likely to occur as a result of increased human presence and noise. As noted in Impact BIO-NP7, most breeding bird species, with a few exceptions, are protected under the Migratory Bird Treaty Act. Measures must be in place to protect such resources in the event that the appropriate take permits are not obtained.
Mitigation BIO-PA5: To reduce the potential for impacts to breeding birds during construction, the City of St. Helena shall implement the measures outlined in Mitigation BIO-NP7.
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Significance after Mitigation. Less than significant.
Impact BIO-PA6: Construction activities could result in direct disturbance, displacement, and/or mortality to terrestrial wildlife species. (Adverse but less than significant and short-term)
To facilitate construction, aquatic and upland habitats would be modified and/or temporarily destroyed, potentially resulting in disturbance, displacement, or mortality to common wildlife species (i.e., reptiles, amphibians, and mammals). While these impacts are not considered significant, they would have an adverse short-term effect on local wildlife communities. Mobile wildlife species would be displaced as part of the initial construction activities, and these species would likely colonize adjacent habitats. Direct mortality could result to non-mobile species.
Mitigation BIO-PA6: Adverse but less than significant impacts do not require mitigation; however, to avoid and/or reduce the potential for direct disturbance, displacement, and/or mortality to common wildlife species (i.e., reptiles, amphibians, and mammals) during construction, the City of St. Helena shall implement the protective measures outlined in Mitigation BIO-NP8.
Significance after Mitigation. Less than significant.
Impact BIO-PA7: Disposal of materials at Lower York Creek Reservoir and alteration of York Creek could result in the disturbance/loss of jurisdictional wetlands and/or other waters of the U.S. (Potentially significant and long-term)
Potential jurisdictional wetlands and other waters of the U.S. were identified at the LYCR based on the presence of at least one wetland parameter and the presence of an Ordinary High Water Mark. Utilizing the LYCR as a disposal and/or reuse site could result in filling or altering such resources. In addition, York Creek is a perennial stream and is considered an “other waters of the U.S.” These areas are potentially subject to the jurisdiction of the Corps under Section 404 of the Clean Water Act, SFBRWQCB under Section 401 of the federal Clean Water Act or Porter Cologne, and CDFG under Section 1600 of the California Fish and Game Code. Filling or altering potential jurisdictional wetlands and/or other waters would result in a significant impact.
Mitigation BIO-PA7: If it is infeasible to avoid filling or altering potentially jurisdictional wetlands and/or other waters of the U.S. during construction, the City of St. Helena shall implement the measures outlined in Mitigation BIO-NP9.
Significance after Mitigation. Less than significant.
Impact BIO-PA8: Construction activities could result in damage and/or mortality to special-status plant species if they are present in the project area. (Potentially significant and short-term)
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Long-term habitat quality in portions of the project area, primarily the Upper York Creek Reservoir, is anticipated to improve over existing conditions as a result of the proposed project, enhancing habitat opportunities for special-status plant species, particularly those requiring wetland and riparian habitats. However, construction will result in significant ground disturbance and vegetation removal in the project area, which could result in damage or mortality to special-status plant species if they occur in the project area. No summer blooming special-status plant species were observed in the project area during a survey conducted in June 2006. A plant survey will be conducted in spring 2007 to determine whether spring blooming special-status plant species are present. If no special-status plants are observed during the spring 2007 survey, special-status plants can be considered absent from the project area, and, therefore, no adverse impacts are anticipated from construction activities. If special-status plants are found during the survey, mitigation measures will be implemented to reduce or eliminate impacts to the species.
Mitigation BIO-PA8: To reduce the potential for impacts to special-status plants during construction, the City of St. Helena shall implement the measures outlined in Mitigation BIO-NP10.
Significance after Mitigation. Less than significant.
Impact BIO-PA9: Native wetland and riparian vegetation around the upper and lower reservoirs will be impacted during construction, resulting in a temporary loss of habitat and increasing the likelihood of establishment of invasive non-native, disturbance-adapted plant species, which could inhibit native vegetation establishment and cause a permanent loss of biotic functions and values. (Potentially significant and short-term)
Construction will result in significant ground disturbance and removal of wetland and riparian vegetation around both the upper and lower reservoirs. Such actions are potentially subject to regulatory jurisdiction by the Corps, San Francisco Bay Regional Water Quality Control Board, and California Department of Fish and Game. Long-term habitat quality around the Upper York Creek Reservoir is anticipated to improve as a result of the proposed project. Vegetation removal will result in a temporary loss of biotic functions and values, including plant and wildlife habitat, stream shading, erosion control, and species diversity. In addition, decreased ground shading and the exposure of bare mineral soil caused by vegetation removal provide recruitment opportunities for invasive non-native, disturbance-adapted plant species. If not controlled, invasive non-native species could inhibit natural vegetation recovery, causing a permanent loss of biotic functions and values.
Mitigation BIO-PA9: To reduce impacts to native wetland and riparian vegetation and the potential for establishment of invasive non-native species during construction, the City of St. Helena shall implement the measures outlined in Mitigation BIO-NP11.
Significance after Mitigation. Less than significant.
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Impact BIO-PA10: Native upland vegetation will be impacted during construction activities. Removal of vegetation can result in a temporary loss of plant and wildlife habitat, increased erosion, and establishment of invasive non-native, disturbance-adapted plant species, which could inhibit native vegetation establishment and result in a permanent loss of biotic functions and values. (Adverse but less than significant and short-term).
Native and non-native upland vegetation will be removed from the access road and other upland areas during construction activities. This includes mixed evergreen forest and redwood forest at Upper St. Helena Reservoir and foothill pine-oak woodland around Lower York Creek Reservoir. In addition, non-native upland vegetation, including ruderal vegetation around Upper York Creek Reservoir, ruderal and non-native grassland around Lower York Creek Reservoir, and ruderal vegetation at Spring Mountain Vineyard, will be impacted during project construction.
Mitigation BIO-PA10: Adverse but less than significant impacts do not require mitigation; however, to avoid and/or reduce the reduce the adverse effects of vegetation removal associated with project construction, the City of St. Helena shall implement the protective measures outlined in Mitigation BIO-NP12.
Significance after Mitigation. Less than significant.
3.3.5 Full Dam Removal: Impacts and Mitigation Measures The Full Dam Removal Alternative is designed to restore the ecological connectivity between habitats upstream and downstream of the dam and provide for a natural sediment transport system. Central California Coast (CCC) steelhead migration would be restored to 100% effectiveness. This alternative allows for the removal of 100% of sediment behind the dam eliminating the threat of future sediment releases and removal of nearly 100% of the actual dam material. A 23-foot wide natural stream channel with a 30-foot wide floodplain bench would be restored. In addition, 2.2 acres of streambank (0.4 acres), terrace (0.6 acres), and riparian zone (1.5 acres) would be revegetated. Approximately 1.7 miles (8,855 feet) of aquatic habitat would become available to CCC steelhead including 0.30 acres of pool, 0.33 acres of flatwater, and 0.85 acres of riffle habitat, totaling 1.5 acres. This reach could potentially support between 825 and 1,810 juvenile steelhead annually under current habitat conditions (Corps 2006a).
Removing the right wall of the spillway (looking downstream) would require stabilization of the hillsides and Spring Mountain Road. Full removal of the dam would generate approximately 45,000 cubic yards of materials (Corps 2006a). Materials not utilized during ecosystem restoration would be reused or disposed of at LYCR, SMV, and Clover Flat landfill. Materials deposited at LYCR would impact 0.52 acres of freshwater wetland habitat, 0.99 acres of open water habitat, 0.22 acres of foothill pine-oak woodland, 0.24 acres of non-native grassland, and 0.02 acres of ruderal habitat. Acres of impact for freshwater wetland and open water are based on the preliminary delineation. This delineation is subject to verification by the Corps and may change as a result. 3.76 acres of ruderal habitat would be impacted at SMV. Significant biological impacts for the disposal of materials at Clover Flat Landfill are not anticipated, and, therefore, they are not addressed in this section.
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Under the Full Dam Removal Alternative, an additional 0.2 acres of habitat and a 30-foot wide floodplain bench would be restored as compared to the small notch preferred alternative. This alternative would result in an additional 6,100 cubic yards of materials being generated and disposed of LYCR.
Biological impacts from the full dam removal would be the same as those described for the Preferred Alternative. Mitigation will reduce impacts to less than significant (Mitigations BIO– PA1, BIO-PA2, BIO-PA3, BIO-PA4, BIO-PA5, BIO-PA6, BIO-PA7, BIO-PA8, BIO-PA9, and BIO- PA10).
3.3.6 Fish Ladder: Impacts and Mitigation Measures The Fish Ladder Alternative is designed to create a concrete step-pool/weir fish ladder cut into the dam. This design provides 65 to 95% effectiveness for upstream Central California Coast (CCC) steelhead migration and a small degree of ecological connectivity between habitats upstream and downstream of the dam. The fish ladder allows for the removal of 37% of sediment behind the dam reducing, but not eliminating, the threat of future sediment releases and removal of 52% of the actual dam structure. The Fish Ladder Alternative does not allow for natural sediment transport and would require on-going maintenance to prevent it from becoming clogged with sediment and other debris. The fish ladder would operate at maximum efficiency during winter months and would be designed to accommodate a water depth of 12 inches so as to allow for a fish jump height of 12 inches or less (Corps 2006a). The fish ladder would be essentially dry during the summer months. Revegetation of 1.9 acres of habitat would occur including 0.4 acres of streambank, 0.9 acres of terrace, and 0.6 acres of riparian zone.
The Fish Ladder Alternative would generate approximately 19,000 cubic yards of materials. Materials deposited at LYCR would impact 0.22 acres of freshwater wetland habitat, 0.33 acres of open water habitat, 0.15 acres of foothill pine-oak woodland, 0.1 acres of non-native grassland, and 0.01 acres of ruderal habitat. Acres of impact for freshwater wetland and open water are based on the preliminary delineation. This delineation is subject to verification by the Corps and may change as a result. 3.76 acres of ruderal habitat would be impacted at SMV. Significant biological impacts for the disposal of materials at Clover Flat Landfill are not anticipated, and, therefore, they are not addressed in this section.
Biological impacts from the fish ladder would be the same as those described for the Preferred Alternative (Impact BIO-PA1, BIO-PA2, BIO-PA3, BIO-PA4, BIO-PA5, BIO-PA6, BIO-PA7, BIO- PA8, BIO-PA9 and BIO-PA10). Additional impacts are described below.
Impact BIO-FL1: The fish ladder would act as a partial, unnatural, upstream and downstream migration barrier to fish and other aquatic species. (Potentially significant and long-term)
Given the seasonal variation in flows in York Creek and the nature of fish ladder designs, fish passage would likely be restricted to the rainy season (December through April). The fish ladder would be completely dry during summer, restricting downstream migration of smolts and local migration and dispersal of other aquatic species. In addition, during the winter months, the ladder is likely to clog with sediment and debris during large storm events. Debris jams would further restrict fish passage by blocking or lowering the effectiveness of the ladder. The ladder would be designed so that each jump between boxes will be less than 12 inches
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when water is present. While this dimension is suitable for migrating steelhead, it may not be adequate for smaller fish and other aquatic species, and they may be limited in their ability to migrate throughout the reach year-round.
Mitigation BIO-FL1: Improved fish passage and restoration of the project site would be considered mitigation for any impacts to fish and aquatic species migration, but they would not reduce the impact to less than significant. Restored site conditions would be a significant improvement over existing conditions.
Significance after Mitigation. Significant and unavoidable.
3.3.7 Section References Berner, M., B. Grummer, R. Leong, and M. Rippey. 2003. Breeding Birds of Napa County, California. Napa-Solano Audubon Society, Vallejo, California.
California Department of Fish and Game (CDFG). 2000. A List of Freshwater, Anadromous, and Euryhaline Fishes of California. California Fish and Game 86(4):244-258.
California Department of Fish and Game (CDFG). 2002. California Climate Based on the Köppen Classification System. GIS coverage. Wildlife and Habitat Data Analysis Branch, Sacramento, California.
California Department of Fish and Game (CDFG). 2003. List of California Terrestrial Communities Recognized by The Natural Diversity Database. California, September 2003. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2006a. California Natural Diversity Database, RareFind Version 3.1.0. California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2006b. Complete List of Amphibian, Reptile, Bird, and Mammal Species in California, March 2006. California Department of Fish and Game Sacramento, California.
California Department of Fish and Game (CDFG). 2006c. Special Animals, February 2006. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2006d. State and Federally Listed Endangered and Threatened Animal of California, October 2006. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2007a. Special Vascular Plants, Bryophytes, and Lichens List, January 2007. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
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California Department of Fish and Game (CDFG). 2007b. State and Federally Listed Endangered, Threatened, and Rare Plants of California, January 2007. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Invasive Plant Council. 2006. Invasive plant inventory. Accessed at: http://portal.cal- ipc.org/weedlist
California Native Plant Society. 2006. Inventory of Rare and Endangered Plants (online edition, v6-05b). California Native Plant Society. Sacramento, California. Accessed at: http://www.cnps.org/inventory.
Cox, Bill. 2002. Memorandum from Bill Cox, District Fishery Biologist, to Lt. Don Richardson. Subject: York Creek, Napa County. September 27, 2002.
Department of Water Resources (DWR). 2003. Biological Assessment for the York Creek Diversion Modification Project, City of St. Helena. Prepared for the City of St. Helena. May 21, 2003.
Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. Technical Report Y-87-1. U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg, Mississippi.
Hickman, J. C. (ed.). 1993. The Jepson Manual: Higher Plants of California. University of California Press. Berkeley, California.
Holland, R.F. 1986. Preliminary Descriptions of the Terrestrial Natural Communities of California. California Department of Fish and Game, Sacramento, California.
Jones & Stokes. 2006. Biological Assessment, St. Helena Comprehensive Flood Protection Project. Prepared for the City of St. Helena. Revised July 2006.
Napa County Resource Conservation District (NCRCD). 2005. Central Napa River Watershed Project, Salmonid Habitat Form and Function. Prepared for California Department of Fish and Game. October 2005.
National Oceanic and Atmospheric Administration’s National Marine Fisheries Service (NOAA Fisheries Service). 2006. ESA Salmon Listings. Accessed at: http://www.nwr.noaa.gov
Nelson, James R. 1987. Rare Plant Surveys: Techniques for Impact Assessment. From proceedings of a California Conference on the Conservation and Management of Rare and Endangered Plants. California Native Plant Society. Sacramento, California.
Prunuske Chatham, Inc. (PCI). 2004. Letter from Jennifer Michaud, Wildlife Biologist, to National Marine Fisheries Service. Subject: York Creek Diversion Modification Project, City of St. Helena, Napa County, Summary of Fish Relocation Activities. November 4, 2004.
Prunuske Chatham, Inc. (PCI). 2006a. California Red-legged Frog (Rana aurora draytonii) Site Assessment, York Creek Sediment Removal Project, City of St. Helena, May 2006.
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Prunuske Chatham, Inc. (PCI). 2006b. Letter from Jennifer Michaud, Wildlife Biologist, to Greg Martinelli, Department of Fish and Game. Subject: York Creek Sediment Removal Project, Notification Number: 1600-2006-0224-3, Summary of Fish Relocation Activities. October 17, 2006.
Riparian Habitat Joint Venture (RHJV). 2004. The Riparian Bird Conservation Plan: A Strategy for Reversing the Decline of Riparian Associated Birds in California, Version 2.0. California Partners in Flight. Accessed at: http://www.prbo.org/calpif/plans.html.
Sawyer, J.O and T. Keeler-Wolf. 1995. A Manual of California Vegetation. California Native Plant Society. Sacramento.
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California. U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
U.S. Army Corps of Engineers (Corps). 2006b. Draft Environmental Assessment: Upper York Creek Ecosystem Restoration Project, Napa County, California. U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006.
U.S. Department of Agriculture, Soil Conservation Service (USDA). 1978. Soil Survey of Napa County, California.
U.S. Fish and Wildlife Service (USFWS). 1998. California Freshwater Shrimp (Syncaris pacifica Holmes) Recovery Plan. U.S. Fish and Wildlife Service, Portland, Oregon. 94 pp.
U.S. Fish and Wildlife Service (USFWS). 2005. Revised Guidance on Site Assessment and Field Surveys for California Red-legged Frog (Guidance), August 2005. U.S. Fish and Wildlife Service.
U.S. Fish and Wildlife Service (USFWS). 2006. On-line endangered species lists. Accessed at: http://www.fws.gov/sacramento/es/spp_list.htm.
University of California, Santa Barbara (UCSB). 1998. California Gap Analysis Project: Land Cover for California. GIS coverage. Santa Barbara, California.
Zeiner, D.C., W.F. Laudenslayer, K.E. Mayer, and M. White. 1990. California’s Wildlife: Volumes I, II, & III. California Department of Fish and Game. Sacramento, California.
3.3.7.1 Federal Register, Codes, and Regulations
33 CFR 328.3 55 FR 26114 57 FR 1796 62 FR 43937 70 FR 52488 71 FR 19243
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71 FR 25813 71 FR 834 16 USC §668a-d 33 USC § 403 (Section 10 of the Rivers and Harbors Act of 1899) 16 USC §703-712 33 USC § 1344 (Section 404 of the Clean Water Act)
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3.4 Cultural Resources 3.4.1 Setting
3.4.1.1 Ethnographic Setting The project area lies within the territory historically occupied by the tribal group known as the Wappo, which belong to the Yukian language family, a very small language family that also includes the Yuki, the Coast Yuki, and the Huchnom tribal groups. The territory of the Wappo is subdivided according to five mutually intelligible dialects that were spoken by the Wappo tribal group: the Western, Northern, Central, Southern, and Clear Lake groups. The project area lies in the Central Wappo territory. (Guldenbrein 2007)
Prehistoric Archaeological Resources Napa County was a rich resource base and home to Native Americans for thousands of years (Jones & Stokes and EDAW, Inc. 2005). A survey for potential archeological resources in the project area was conducted in 2001, including records and literature search, a search of the Native American Heritage Commission’s Sacred Lands File, and a field survey. No prehistoric archaeological resources were identified within the proposed project area, and a Negative Archaeological Survey Report was prepared. In addition, individual letters were sent to Native American contacts identified by the Native American Heritage Commission requesting information on cultural resources in the project area. (DWR 2004)
In 2007, searches of records, the Sacred Lands File, and literature were initiated for the project site and potential placement sites, and individual letters were sent to Native American contacts identified by the Native American Heritage Commission requesting information on cultural resources in the project area. A prehistoric archaeological site was identified, and, based on an evaluation of the environmental setting, it was determined that there was a moderate likelihood that unrecorded cultural resources exist at the lower reservoir (Guldenbrein 2007).
A professional consulting archaeologist was retained by the City to research and assess the site and proposed project. After conducting a literature search and surface examination, the archaeologist determined that a prehistoric site is definitely present within the proposed project area. The archaeologist further determined that the site has been highly disturbed by prior construction activities and, due to this prior disturbance, the site would not qualify as a significant resource that would be potentially eligible for the National Register of Historic Places (NRHP). Therefore, the archaeologist determined that a special mitigation plan during project activities is not required. The archeologist does recommend that, should specific artifacts be discovered during project activities, work be halted until a qualified cultural resource consultant has evaluated the situation. No collection of artifacts by project personnel will be permitted. (Flynn 2007)
3.4.1.2 Historic Setting The Upper St. Helena Dam was constructed in 1900, and the adjacent concrete spillway was added in 1933. The dam was essential to the growth of the City of St. Helena in the early 20th century because it expanded the capacity of the original water delivery system, making more water available for the increasing commercial and residential uses, as well as for fire protection. When it was completed, the earthen filled dam was 35 feet high and 140 feet long on the crest
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(Eastman 2003); it was raised 15 feet in 1933 when the new spillway was constructed, and the standpipe outlet was installed.
A cultural resources study of the project’s area of potential effects was undertaken as part of the Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project (DWR 2004, quoting Eastman 2003).
3.4.1.3 Historical Resources The Upper St. Helena Dam was formally evaluated pursuant to Section 106 of the National Historic Preservation Act, as amended, and its implementing regulations (36 CFR 800, December 2000) and Section 15064.5 of CEQA by Bright Eastman in 2003. According to Eastman and to Richard Stratford of the Corps (pers. comm., November 2006), the dam appears eligible for listing in the NRHP under Criterion A, “at a local level of significance in the area of community development,” and may also be considered an historical resource for the purposes of CEQA. It is considered eligible for listing on the California Register of Historical Resources (CRHR) pursuant to the California Public Resources Code Section 5024.1(d)(1).
3.4.2 Standards A project would be considered significant if any historical or archaeological resource were abolished or altered in a way to make the relevant history unavailable. Specifically, the project would be considered significant if it would eliminate an important example of a major period of California history or prehistory.
3.4.3 No Project Alternative: Impacts and Mitigation Measures Description Under the No Project Alternative, the historic dam and spillway would remain unaltered, and there would be no impact on historical resources. No disposal of dam material would be required. There may still be a need to utilize one or more of the potential placement sites for on- going maintenance activities. Maintenance personnel will receive a pre-project briefing of potentially-occurring prehistoric resources and measures to avoid impacts. If cultural resources are encountered during project activities, personnel shall avoid altering the materials and their context until a cultural resource consultant has evaluated the situation. Project personnel will not be permitted to collect cultural resources.
3.4.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description The Small Notch Alternative would result in removal of 72% of the historic Upper St. Helena Dam and placement of fill into the historic spillway to provide stability for the adjacent Spring Mountain Road. Placement of materials removed from the dam and reservoir would result in no impact to cultural resources at Spring Mountain Vineyard or Clover Flat landfill. Precautionary measures for prehistoric archaeological resources at the lower reservoir are discussed above in the No Project Alternative.
Impact CUL-PA1: Removal of the of the Upper St. Helena Dam and associated structures would have a significant adverse impact on the historic feeling, design, and association of a resource
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considered eligible for listing in the National Register of Historic Places (NRHP) and the California Register of Historic Resources (CRHR). (Significant, long-term, and unavoidable)
No feasible alternatives could be identified that meet the project objectives of removing this fish passage obstruction while mitigating for adverse impacts to the historical structure and its setting. The dam is a unique historical resource, significant for its role in the development of the City of St. Helena, and alteration of the dam alone will be a significant impact. Therefore, significant impacts to the historical resource are considered unavoidable but justified to improve the aquatic environment of York Creek for steelhead and other species.
Mitigation CUL-PA1: The City will preserve physical information about this historic property by implementing mitigation measures including: • Creation of a record of the dam using photo documentation, drawing, and written data regarding the dam prior to alteration. • Maintenance of documentation showing the dam prior to alteration. • Development of interpretive materials to be incorporated into the City’s website within one year of the date of the dam alteration. • Creation of an exhibit of photographs and graphics of the dam for installation in a public facility in St. Helena within one year of the date of the dam alteration.
Success Criteria CUL-PA1: The website and exhibit discussed above shall be completed by within one year of the dam alteration.
Significance after Mitigation. Significant and unavoidable. 3.4.5 Full Dam Removal: Impacts and Mitigation Measures Description Impact and mitigation from the Full Dam Removal Alternative, which would result in removal of 100% of the historic Upper St. Helena Dam and placement of fill into the historic spillway to provide stability for the adjacent Spring Mountain Road, are discussed in CUL-PA1. Placement of materials removed from the dam and reservoir would result in no impact to cultural resources at Spring Mountain Vineyard or Clover Flat Landfill. Impacts and mitigation measures for impacts to prehistoric archaeological resources at the lower reservoir are discussed above (CUL-NP1).
3.4.6 Fish Ladder: Impacts and Mitigation Measures Description This alternative would create a concrete step-pool/weir fish ladder cut into the dam. Impacts and mitigation are similar to those discussed in CUL-NP1 and CUL-PA1.
3.4.7 Section References Department of Water Resources (DWR). 2004. Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project. January 14, 2004.
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Eastman, B. 2003. Historical Resources Evaluation Report for the Proposed Removal of an Earthen Dam and Diversion Structure on York Creek near the City of St. Helena in Napa County, California. Prepared for the City of St. Helena by Bright Eastman, Anthropological Studies Center, Sonoma State University, Rohnert Park, California.
Flynn, Katherine. 2007. Personal communication with Ms. Flynn, Archaeologist, Archeological Resource Service, Petaluma, CA. Appendix 5.
Guldenbrein, Jillian. 2007. Personal communication with Ms. Guldenbrein, Researcher I, Northwest Information Center, Sonoma State University. Sonoma State University, Cotati, CA. Appendix 5.
Jones & Stokes and EDAW, Inc. 2005. Napa County Baseline Data Report, Version 1 – November 30, 2005. Prepared for the Napa County Conservation, Development and Planning Department. November 2005. Available for viewing on the Napa County website. Accessed at: http://www.co.napa.ca.us/gov/departments/29000/bdr/index.html
Prunuske Chatham, Inc. (PCI). 2007c. Northwest Information Center cultural resources search summary. Technical memo. Appendix 5.
Stratford, Richard. 2006. Personal communication with Mr. Stratford, Cultural Resources Planner, U.S. Army Corps of Engineers. San Francisco, CA. Appendix 5.
U.S. Army Corps of Engineers (Corps). 2006b. Draft Environmental Assessment: Upper York Creek Ecosystem Restoration Project, Napa County, California (EA). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006.
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3.5 Geology, Soils, Landslides, and Seismic Activity 3.5.1 Setting 3.5.1.1 Geology The project site is located within the Coast Ranges geomorphic province of California. This geomorphic province is characterized by a series of discontinuous northwest-trending mountain ranges extending from the Klamath Mountains on the north coast of California to the Transverse Ranges to the south. The Coast Ranges are composed of thick Mesozoic and Cenozoic sedimentary strata that have a complex structure due to intense folding and faulting.
The California Geological Survey and Durham map geologic units in the immediate site vicinity from oldest to youngest as:
Franciscan Complex – Jura-Cretaceous rocks described as undifferentiated mélange consisting of a sheared shale matrix containing a chaotic mixture of fragmented blocks of chert, metamorphic rock, greenstone, serpentinized peridotite and other rocks.
• Ultramafic Rocks – Jura-Cretaceous rock consisting of continuous or sheared lenticular blocks, including serpentinite. • Sonoma Volcanics – Pliocene-age volcanic rocks consisting of andesitic flows and tuffs, welded tuffs, minor amounts of olivine basalt and dacite. Also includes interlayered sandstones, conglomerates, and siltstones. • Recent Alluvium – Holocene deposits within and along the margins of York Creek, comprised of unconsolidated sandy silt, sandy silt with clay, sand, gravel and silty gravel. These sediments vary in thickness within the natural channel and have accumulated behind the dam to thicknesses ranging between 17 and 29 feet. The mapping by Durham shows a landslide along the hillside east of York Creek, near the left dam abutment and spillway. Spring Mountain Road crosses this feature, which consists of active landsliding superposed over older, dormant landslide deposits (Blackburn 2006). The active sliding extends about 12 feet below the road and terminates at the concrete spillway, where it has displaced the east spillway wall. The older, dormant slide deposits extend to 40 to 50 feet below the road and dam crest and toes-out near the original (pre-dam) channel bottom.
3.5.1.2 Soils Site soils are mapped by the United States Department of Agriculture (USDA) as Aiken loam and clay loam on 30-50% slopes east of Spring Mountain Road and Forward gravelly loam elsewhere within the immediate project vicinity on 30-75% slopes. The Aiken loam and clay loam is mapped to a depth of about 44 inches and underlain by unweathered bedrock. The Forward gravelly loam is mapped to a depth of about 35 inches and underlain by weathered bedrock. A range of engineering properties for these soils is presented in Table 11.
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Table 11. Soil Properties
Percent Passing Sieve Soil Depth United Soil Liquid Plasticity Soil Texture 4 10 40 200 Name (inches) Classification Limit Index Aiken 0-8 Loam CL-ML, ML 95-100 80-100 70-80 60-70 25-35 5-10 “ 8-14 Clay loam CL, ML 95-100 95-100 80-90 60-70 30-50 10-20 “ 14-44 Clay MH 95-100 95-200 85-95 70-85 50-60 15-25 “ 44-48 Unweathered bedrock
Forward 0-4 Gravelly loam SC-SM, SM 55-80 50-75 40-65 30-50 15-30 NP-10 Gravelly loam, loam CL, CL-ML, “ 4-35 70-85 65-80 50-75 35-60 15-30 5-15 SC, SC-SM “ 35-39 Weathered bedrock
Source: USDA Natural Resources Conservation Service
The Aiken loam has “severe” erosion hazard on slopes of 30-50% while the Forward gravelly loam has “very severe” erosion hazard on slopes of 30-75%. The Aiken loam, clay loam and clay have a low to moderate expansion index while the Forward gravelly loam and loam are non- plastic or have a low expansion index.
The depth of sediment behind the dam varies from 17 to 29 feet. The upper 10 feet of reservoir sediments consist of silty sand and gravel (SM, GM and SP per Unified Soil Classification). These materials typically have greater than 90% passing the 3-inch sieve and contain about 12 to 28% fines, locally less than 1% fines. These materials are non-plastic or have a low expansion index.
3.5.1.3 Seismic Activity The Alquist-Priolo Special Studies Zone Act defines an active fault as a fault that has had surface displacement within Historic (last 200 years) or Holocene (last 11,000 years) time. Late Quaternary or Quaternary age (i.e., the last 1.6 million years) faults that show evidence of surface displacement are considered potentially active.
Regional Faults The distance between the site and recognized Historic, Holocene, and Late Quaternary faults within approximately 30 miles of the site is shown in Table 12. Maximum earthquake magnitudes (moment magnitude) are also shown and are based on seismological data such as maximum historic earthquakes and on geologic data such as fault length and fault displacement parameters. The faults listed are considered to have the greatest potential for impacting the site if they were to rupture.
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Table 12. Historic, Holocene, and Late Quaternary Faults Fault Name Distance and Direction from Site (miles) Mw1 West Napa 10.0 East - Southeast 6.5 Maacama – Gerberville 11.2 North – Northwest 7.5 Rodgers Creek – Hayward 11.4 West 7.3 Hunting Creek – Berryessa 12.9 East 7.1 Concord – Green Valley 19.6 East 6.7 Great Valley 4 20.1 East 6.6 Collayomi 20.8 North – Northwest 6.5 Great Valley 3 23.1 East 6.9 Bartlett Springs 29.0 North 7.6 San Andreas 31.5 West 7.9 1 Maximum Moment Magnitude (Blake 2000)
Ground Motion The site is within a seismically active area and located in California Building Code (CBC) Seismic Risk Zone 4. Areas within this zone are at a high risk to experience strong ground motions from an earthquake. Based on a Magnitude 7.5 event on the Maacama-Gerberville Fault at a distance of about 11 miles, a peak bedrock ground acceleration of 0.24g is obtained using deterministic procedures (Blake, 2000).
Using probabilistic procedures provided by the California Geological Survey (CGS), the peak horizontal ground acceleration with a 10% probability of being exceeded in 50 years is approximately 0.37g.
3.5.1.4 Potential Geologic/Seismic Hazards Surface Fault Rupture No active faults are mapped through the project site. The nearest active faults are: • West Napa Fault, located about 10 miles to the east, and • Maacama-Gerberville Fault, located about 11 miles to the north-northwest. The site is not located within nor crosses a delineated Alquist-Priolo Earthquake Fault Zone. Therefore, the risk of fault rupture within the project site is low.
Liquefaction Liquefaction is a secondary effect associated with seismic loading. It can occur when relatively loose, granular, saturated soils generally within about 50 feet of ground surface are subjected to ground shaking.
Stream channel deposits within York Creek and the sediments that have accumulated behind the dam consist of granular soils susceptible to liquefaction. Potential impacts from liquefaction are discussed in the impact analysis sections for the No Project and Fish Ladder Alternatives.
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Landslides Landslides most commonly occur in areas of and adjacent to steep slopes. They are triggered by static (i.e., gravity) or dynamic (i.e., earthquake) forces. The slopes within the upper portions of the York Creek watershed are steep and naturally prone to slope instability.
The project will remove a portion of the existing dam and may impact slope stability and service along Spring Mountain Road in the area of the known landslide. Potential impacts from landsliding are discussed further in the Preferred Small Notch and Full Dam Removal Alternatives sections below.
3.5.1.5 Soil-Related Hazards Erosion Erosion involves the removal of earth materials from one area with deposition to another area. It occurs by natural processes or human activities. The rate of erosion varies depending on a soils capacity to drain water, slope angle and length, amount of groundcover, and human influence. Excessive erosion can cause sedimentation and damage to waterways and riparian habitat, obstruct drainage facilities, and clog lakes and reservoirs. Potential impacts from erosion are discussed in the Hydrology and Hydraulics and Water Quality sections (3.8 and 3.11, respectively).
Expansive Soils Expansive soils are mostly comprised of clays, which swell when water is absorbed and shrink when dried. Over a long period of time, expansive soils can cause damage to structures as a result of repeated shrink-swell episodes. Soils at this site vary from non-plastic to moderately expansive.
3.5.2 Standards Geologic, soils-related, or seismic hazard impacts are considered significant if implementation of the project were to:
• Be located on, or occur within, a geologic unit or soil that is unstable or that would become unstable as a result of the project, and result in a substantial increase in on- or off-site landslide potential. • Cause a substantial increase in soil erosion and loss of topsoil in the project area. • Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code, creating substantial risks to life or property. • Expose people, property, or sensitive natural resources to potential substantial adverse effects involving: o rupture of a known earthquake fault. o strong seismic ground shaking. o seismic-related ground failure, including liquefaction.
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3.5.3 No Project Alternative: Impacts and Mitigation Measures Description The dam provides limited support to the spillway and Spring Mountain Road, which minimizes ground movement in the area of the known landslide. The stability of the road and side slopes, conditions affecting soil erosion and loss of topsoil, and soils within the project will remain unchanged. The site is not located within nor crosses a delineated Alquist-Priolo Earthquake Fault Zone. Therefore, the risk of fault rupture within the project site is considered low, and impacts related to fault rupture for this project are considered less than significant.
Impact GEO–NP1: Potential for project to expose people, property, or sensitive natural resources to substantial adverse effects involving strong seismic ground shaking and seismic-related ground failure, including liquefaction. (Potentially significant)
Strong ground shaking caused by one or more nearby active or potentially active faults is an unavoidable hazard for this site. The intensity of such an event would depend on the distance to the causative fault, moment magnitude, and duration of shaking. The potential for detrimental effects associated with seismically-induced ground failure of the existing dam and reactivation of the landslide cannot be precluded. Therefore, the risk of detrimental effects to the site associated with ground motion from nearby faults is considered potentially significant.
Granular sediment susceptible to liquefaction will remain behind the dam, and the potential for liquefaction to occur locally at this site exists. However, the risk of detrimental effects to the site is considered low. Therefore, impacts related to liquefaction for this project are considered potentially significant.
Mitigation GEO–NP1: If the City selects the No Project Alternative, seismic stabilization would be planned and implemented. Further review under CEQA would be required.
Significance after Mitigation: Less than significant.
3.5.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description The Preferred Small Notch Alternative, which has a 23-foot wide channel through the notch and no allowable space for a floodplain, is the preferred geotechnical solution for reducing or removing barriers to fish passage and at the same time maintaining a stable road. Geotechnical modeling results support the Corps recommendation favoring a notch. This alternative also appears stable without geotechnical slope stability measures. However, Corps geotechnical staff recommended incorporating new data from piezometers and inclinometers to better determine the need for the recommended stabilization measures. Under this alternative, the spillway will remain in place and will be backfilled to provide continued support for the existing road. (Corps 2006a Appendix C)
Except for the known landslide, partial removal of the dam and restoration of the streambed to the level of the natural streambed are not expected to adversely impact the natural slopes at the
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site. The Corps evaluated slope stability in the area of the known landslide; their proposed design includes measures to provide slope stabilization. See full discussion in Appendix C of the Draft Detailed Project Report Upper York Creek Ecosystem Restoration Project (Corps 2006a).
A significant amount of the granular sediment susceptible to liquefaction will be excavated from behind the dam, reducing the risk for liquefaction to occur, and, therefore, impacts related to liquefaction for this project are considered less than significant. Potential erosion caused by construction will be controlled by means of standard construction practices as required by the project’s Storm Water Pollution Prevention Plan (SWPPP). Long-term erosion control will be provided through establishing vegetation in areas disturbed by construction, placing boulder riprap interplanted with native species, and terracing.
Soils within the project area are comprised of sand, gravel, loam, clay loam, clay, and gravelly loam and vary from non-plastic to moderately expansive. Expansive soils are not considered to pose a significant hazard since no permanent structures are planned for this project. Therefore, impacts related to expansive soils for this project are considered less than significant.
Impact GEO– PA1: Potential for project to expose people, property, or sensitive natural resources to substantial adverse effects involving slope failure due to removal of the dam at the toe of a landslide. (Potentially significant)
There is an existing landslide under Spring Mountain Road adjacent to the dam. Landslides may be triggered due to loss of lateral and vertical support through removal of the dam embankment. On the northeast side of Spring Mountain Road, exposures of welded tuff (Sonoma Volcanics) and serpentinite are clearly visible in the materials exposed by a recent landslide. Treadwell & Rollo (2003) reported that Spring Mountain Road consists of 6-inch thick asphalt pavement and 24-inch thick compacted road base and appears to have been built on a surface cut into the native serpentine bedrock material. Serpentinite is notorious for relaxing or rebounding, leading to diminished intact shear-strength when unloaded, which may lead to landslides. (Corps 2006a Appendix C)
Mitigation GEO– PA1: The Corps proposes to stabilize the landslide area by leaving the existing spillway in place and buttressing it will fill from the project site. Two rows of soil anchors and subdrains will also be installed. The existing landslide area is presently being monitored with equipment such as slope inclinometers and piezometers. During construction, slopes within the project site will be reviewed to evaluate slope stability, identify/evaluate possible slope defects, and determine if supplemental stabilization measures should be implemented. Since slope stabilization measures and geotechnical review of slopes during construction are planned for this project, impacts related to slope stability are considered less than significant. (Corps 2006a Appendix C)
Significance after Mitigation: Less than significant.
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3.5.5 Full Dam Removal: Impacts and Mitigation Measures Description The difference between the Preferred Alternative and Full Dam Removal is that the existing spillway will be removed rather than filled to provide stability for the road. Subdrains and three rows of soil anchors would be installed rather than two. (Corps 2006a Appendix C)
Impact GEO– FR1: Potential for project to expose people, property, or sensitive natural resources to substantial adverse effects involving slope failure due to removal of the dam at the toe of a landslide. (Potentially significant)
The impacts discussed in GEO-PA1 are similar in the Full Removal Alternative, except the spillway will be removed rather than filled. This will require additional geotechnical measures to provide slope and road stability.
Mitigation GEO– FR1: The Corps proposes to stabilize the landslide area by installing three rows of soil anchors and subdrains. As with the Preferred Alternative, slopes within the project site will be reviewed to evaluate slope stability during construction, identify/evaluate possible slope defects, and determine if supplemental stabilization measures should be implemented. Since slope stabilization measures and geotechnical review of slopes during construction are planned for this project, impacts related to slope stability are considered less than significant. (Corps 2006a Appendix C)
Significance after Mitigation: Less than significant.
3.5.6 Fish Ladder: Impacts and Mitigation Measures, Success Criteria Description The stability of slopes will remain essentially unchanged. The dam provides limited support to the spillway and Spring Mountain Road, which minimizes ground movement in the area of the known landslide. Geology, soils, landslides, and seismic activity impacts and mitigation from the Fish Ladder Alternative would be the same as those described for the No Project Alternative (Impact GEO–NP1).
3.5.7 Section References Blackburn Consulting, Inc. 2006. Geotechnical Data Report, Upper York Creek Dam Removal Project, St. Helena, California. January 17, 2006.
Blake, Thomas F. 2000. EQFAULT: A Computer Program for the Estimation of Peak Horizontal Acceleration from 3-D Fault Sources, Version 3.00. April 2000.
California Geological Survey. 1999. Geologic Map of the Santa Rosa Quadrangle, Map No. 2A, Scale 1:250,000.
California Geological Survey. 2006. Seismic Shaking Hazards in California. Accessed November 27, 2006 at: http://www.consrv.ca.gov/cgs/rghm/pshamap/pshamain.html.
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Durham, J.B. 1979. Geology and Landslides of the Calistoga 15’ Quadrangle, CA. California Department of Forestry, Title II Data Compilation Project, Scale 1:62,500.
Innovative Technical Solutions, Inc. (ITSI) 2003. Final Report HTW Assessment Upper York Creek Ecosystem Restoration Project St. Helena, California. Prepared for U.S. Army Corps of Engineers San Francisco District. December 2003.
United States Army Corps of Engineers. 2006a. Draft Detailed Project Report Upper York Creek Ecosystem Restoration Project, Napa County, California, dated September 1, 2006. Accessed November 27, 2006 at: http://www.spn.usace.army.mil/projects/documents.html.
United States Department of Agriculture, Natural Resources Conservation Service. 2006. Web Soil Survey. Accessed November 27, 2006 at: http://websoilsurvey.nrcs.usda.gov/app/.
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3.6 Global Climate Change 3.6.1 Setting The earth is getting warmer. Eleven of the last twelve years are the warmest years on record; over the last hundred years, the average temperature of the earth has risen 1.4º F, and the trend is going to continue (IPCC 2007; NAS 2006; Pew 2006). This change is causing, and will continue to cause, profound effects on the environment and human endeavors.
3.6.1.1 Greenhouse Effect Human activities are increasing the levels of certain gases, known as greenhouse gases (GHGs), above natural background levels. Greenhouse gases are carbon dioxide (CO2), methane (CH4), nitrous oxide (NOx), hydroflourocarbons, perflourocarbons, and sulfur hexafluoride. These gases act very much like a greenhouse does, allowing sunlight in but retaining some of the heat that would otherwise escape, thereby warming the interior. Earth’s climate naturally has a greenhouse effect. Without it, the surface temperature would be about 50º F colder, and the planet would not support life. Earth’s temperatures vary within a range, partly based on the concentrations of GHGs in the atmosphere.
Since the industrial revolution, humans have been adding GHGs to the atmosphere at an accelerating pace. The main source of GHGs is burning of fossil fuels for energy, transportation, and industrial uses. GHGs other than CO2 may be result from industrial processes, chemical production, and agriculture, which produces methane and nitrous oxide.
16000 14000 12000 10000 8000 6000 4000 2000 0 Other CO2 CH4 N20 GHGs California 356 28 33 14 United States 5988 557 387 143 Global 14,910 1700 1050 270
Figure 9. Current Global, National, and State Greenhouse Gas Emissions Data compiled from UNFCCC 2006, EPA 2006e and CCEC 2006
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Greenhouse Gas Emissions in California by Economic Factor
Others Agriculture & 8% Energy Forestry 22% 8%
Industry 21% Transportation 41%
Figure 10. California Sources of Greenhouse Gas Emissions Source: CCEC 2006.
Two natural processes reduce the concentration of carbon dioxide in the atmosphere. Sequestration is the storage of carbon by plant uptake during photosynthesis, dissolving into the ocean, or human mechanical processes. Since plants need carbon dioxide to grow, more carbon in the atmosphere can lead to more plant growth, and, therefore, more carbon being removed from the atmosphere. Large trees may store a tremendous amount of carbon. Tropical rainforests and dense temperate forests absorb most of the net carbon removed from the atmosphere, about 2.3 gigatons per year (Grace 2004).
Carbon dioxide is also stored by dissolving in the ocean. This process currently absorbs another 2.3 gigatons carbon per year (Grace 2004). However, the capacity of the ocean surface water to absorb carbon dioxide is limited by the concentration of inorganic carbon already in the water. As the concentration of carbon dioxide in the atmosphere rises, so will the concentration of carbon dioxide in ocean surface waters, thereby decreasing the total amount the ocean can absorb (IPCC 2001). With forests and the ocean absorbing carbon dioxide, humans are adding a net 3.3 gigatons of carbon to the atmosphere each year (Grace 2004).
The natural range of carbon dioxide concentrations in the atmosphere during the last 650,000 years is 180 to 300 ppm (IPCC 2007). Prior to the industrial revolution, atmospheric concentration of carbon dioxide was 280 ppm, which is consistent with temperature history that shows that prior to human-caused (anthropogenic) climate change, the earth was in an interglacial warm period. The atmospheric carbon dioxide concentration has now risen to 379 ppm and is projected to rise to 700 ppm by 2100 at current GHG emission levels (IPCC 2007; Stewart 2007). Although carbon dioxide is the least heat capturing of the gases, its naturally
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large abundance and the rate at which humans are producing it means that it has the single largest effect on heat retention in the atmosphere. Methane and nitrous oxide are also above historic natural levels.
Table 13. Historic and Current Concentrations of Greenhouse Gases. Concentration range Pre-industrial Current Greenhouse Gas over last 650,000 years concentration concentration Carbon dioxide in ppm 180 - 300 280 379 Methane in ppb 320-790 715 1774 Nitrous oxide in ppb 270 319 Source: Data used from IPCC 2007.
As greenhouse gases increase, they are slowly raising the average temperature of the earth. The temperature is projected to increase between 3.2° F and 7.2° F by 2100, depending on how rapidly and effectively humans reduce GHG emissions (IPCC 2007). The phenomenon is often called global warming, but it is more accurately called climate change because the temperature may fall in some areas and increase in others.
3.6.1.2 Physical Effects Climate change does not happen uniformly. Some spots may become substantially hotter or colder while others remain virtually unchanged. Ocean and atmospheric circulation patterns produce a larger temperature change at the poles than at the equator. One of the predicted effects of global climate change is more extreme weather. More intense, frequent, longer duration heat waves are probable.
Average temperatures will be higher in most places, with the largest changes occurring at higher latitudes. This will mean fewer winter chill days, earlier springs, and later falls. Precipitation patterns will also change. Globally, precipitation will likely increase at high latitudes and decrease in more equatorial areas (IPCC 2007). There is less certainty for regional and local predictions. California is likely to continue to have a Mediterranean climate with a cool rainy season and a long, warm, dry season. However, both wet and dry seasons are likely to be warmer with average temperatures predicted to rise between 3° F and 10.5° F by 2100 depending on future emissions of GHGs (CCEC 2006).
Some areas will have more droughts and/or more floods. Rain events, in general, are likely to be more intense but shorter (IPCC 2007). It is not clear whether climate change will increase the number of hurricanes, but they will be stronger as they gather more energy from warmer oceans. This change has already started to occur, with a significant increase in Category 4 and 5 hurricanes, record breaking hurricane years in North America, Asia, and Australia, and the first recorded hurricane in the south Atlantic (Elsner 2006; IPCC 2007).
Another predicted change that has already started to occur is melting of glaciers and the polar ice caps. Most mountain glaciers will be gone in 50 years. The large continental ice sheets on Greenland and Antarctica are losing ice around the edges each year (IPCC 2007; Kerr and Balter 2007). There has always been seasonal melt, but now the trend is consistently for loss of total ice. Melting of glaciers and ice sheets raises sea level. As ocean water becomes warmer, it becomes less dense and expands, thereby contributing to even more rise. Sea level rose an
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approximate 0.17 meters during the 20th century, and the pace is accelerating (IPCC 2007). It may rise an additional 0.5 meters to 1.4 meters during the 21st century (Kerr and Balter 2007).
Earth’s climate is moderated by the continual circulation of water from the equator toward the poles driven by the movement of ocean and air currents. The main driver of ocean currents is the thermal haline cycle. As saltwater chills when it gets near the poles, it sinks and flows under the warmer surface waters back toward the equator where it warms and rises again pushing surface waters toward the poles. The Atlantic current turns under near Greenland. Dynamics of ice melting on Greenland could cause large amounts of fresh water to rapidly enter the north Atlantic. This fresh water would not sink the way the salt water does and could halt the north Atlantic currents. This happened when the glacier that formed the Great Lakes melted and suddenly broke through a natural dam to the north Atlantic. On that occasion, circulation of the Atlantic stopped, and northern Europe became glaciated over a space of perhaps as little as 10 years.
3.6.1.3 Biological Effects Living plants and animals are adapted to a particular temperature range. When temperatures change, species may experience stress that makes them more vulnerable to damage of various kinds. If temperatures shift outside species’ workable temperature range, species may react by moving their geographical range to a more compatible area or adjusting their phenology (event timing) to avoid the warmest times. If a species is unable to adapt, changing weather patterns may be fatal. This is already beginning to happen with coral in equatorial areas where many species live near the upper limit of their temperature range. In the northern hemisphere, 41% of 1,598 species studied have already made some adjustment for climate change (Parmesan 2006).
Additionally, shifting ranges can create domino effect ecological challenges by changing species interactions. Each species reacts separately to changes in temperature and may make different amounts of shift, either because they have different temperature needs or different abilities to disperse. This may result in organisms that previously lived in community moving apart, resulting in disruption of food webs and pollination, increasing invasive species, and other changes in the multiplicity of interactions that provide ecological stability.
Shifting timing (phenology) is also likely to disrupt many species interactions. This happens because species, even those that interact with each other, have separate changes in timing. For example, in Europe caterpillars have started to emerge almost two weeks sooner, while the trees on which they depend are leafing out only a few days sooner, so the caterpillars no longer have sufficient food. This sort of interaction has become almost common with desynchronization of predator and prey species, flowers and pollinators, etc.
Locally, special-status species such as steelhead and California red-legged frog are already being strongly negatively impacted by the invasion of warm water fish species and bullfrogs. There is not yet research showing whether global climate change will intensify that pressure. In some places, temperature effects on aquatic and marine algae are causing less productivity at the primary level on which the entire food web depends, causing losses throughout the ecosystem.
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3.6.1.4 Effects on Humans More intense heat waves have a direct impact on humans by causing heat illness and death. In summer 2004, Europe experienced a heat wave that killed 30,000 people (Ackerman and Stanton 2006). A similar heat wave in 2006 caused far fewer fatalities because coping mechanisms were better developed. In southern California, there may be more than 100 days a year with temperatures over 90° F, and in Sacramento it could be over 95º F for more than 100 days (CCEC 2006). This intense heat could make air quality worse. The frequency, duration, and intensity of periods in which ozone and other air pollutants form are likely to increase (CCEC 2006).
In California, a 70-90% projected loss of the Sierra snowpack could result in severe water shortages with agriculture having 25% less water available. Effects on agriculture will also include added challenges from changed rainfall, soil drying and salination from increased evaporation, increased pathogens, and disrupted pollination. Fruit and nut trees may not have enough chill hours to set fruit. In fact, crop yields are already being affected. Napa County is highly likely to become too warm for growing quality wine grapes and may become too warm for even table grapes (CCEC 2006).
Drying soils will not only have an effect on agriculture but also on natural systems. More xeric (drought tolerant) species may have an advantage. However, some species will just stay where they are. More dry plants together with more dry soils will increase the risk of forest fire. In California, there might be an increase of 55% in the incidence of forest fires if GHGs are not highly limited (CCEC 2006).
In California, flooding will increase in low-lying coastal areas with more wave damage during storms. Rising sea levels may stress the levee system in the Sacramento River delta and elsewhere.
3.6.1.5 Climate Change Effects on the Proposed Project A primary purpose of the proposed project is to open upstream habitat in York Creek for steelhead use. Since global climate change is causing many organisms to shift their ranges, it is relevant to consider whether York Creek will continue to be good habitat for steelhead into the future. Of the three kinds of salmonids that live on the California central coast, steelhead have the most temperature plasticity for warm waters. This allows steelhead to have a more southern end to their range, near Los Angeles, as opposed to coho and Chinook, neither of which extend beyond Santa Cruz (Adams 2007).
Juvenile steelhead have a thermal maximum of 24º C. It is possible that stream temperatures might rise by a small amount, and this could increase the number of days that the water exceeds the thermal maximum. However, complex topography and groundwater recharge in the western United States make forecasts for any particular watershed problematic.
St. Helena is near the center of the range of the Central Coast ESU20 of steelhead, which extends from Santa Cruz in the south past Ukiah to the north. The project area could remain viable habitat when more southern areas can no longer support steelhead. This would increase the importance for the species of having access to the well-protected habitat above the Upper St.
20 Evolutionary significant unit.
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Helena Dam on York Creek. Climate change predictions are not sufficiently specific to make accurate local forecasts, but range centers like York Creek will, in general, have more chance of remaining viable habitat.
3.6.1.6 Regulatory Setting The Intergovernmental Panel on Climate Change (IPCC) is a scientific body established by the United Nations Environment Programme and the World Meteorological Organization to assess scientific information relevant to human-induced climate change, impacts, and mitigation. Although the IPCC has no regulatory authority, it is considered an authoritative source for information on climate change because of the cooperative efforts of large numbers of scientists from many countries. The Fourth Assessment Report, now being produced, is the work of more than 400 scientists and is being peer-reviewed by more than 1,000 others.
The federal government has several pieces of proposed legislation on global warming, but no laws have been enacted at this time. California has a strong regulatory framework in place. On June 1, 2005, Governor Schwarzenegger published Executive Order S-3-05 directing that, because climate change threatens air quality, water supply, coastal resources, and agriculture in California, the state will reduce greenhouse gas emissions to 1990 levels by 2020 and to 80% below 1990 levels by 2050. The order directed the California EPA to oversee efforts, coordinating with the Business, Transportation and Housing Agency, Department of Food and Agriculture, Resources Agency, Air Resources Board, Energy Commission, and Public Utilities Commission. They were further ordered to report to the governor and the legislature by 2006 and biannually thereafter on progress toward meeting these emission levels.
Last year, the state of California enacted Assembly Bill 32 (AB 32), the California Global Warming Solutions Act of 2006. The law states, “Global warming poses a serious threat to the economic well-being, public health, natural resources, and the environment of California.” The law codifies the greenhouse gas reduction of 1990 levels by 2020, transfers leadership of the interagency cooperation to the Air Resources Board, implements mandatory reporting by industry of greenhouse gas emissions, requires voluntary, regulatory, and market incentive mechanisms for reducing greenhouse gases, and adopts early implementation actions. Significant time points included in the law are shown below. The California Air Resources Board is now holding frequent public meetings on all different aspects of AB 32 implementation.
AB 32 Time Points
July 1, 2007 Adopt Early Action Measures January 1, 2008 Establish GHG emission cap based on 1990 Adopt mandatory reporting rules for GHGs January 1, 2009 Adopt a plan for achieving emission levels January 1, 2010 Have implemented Early Action Measures January 1, 2011 Adopt regulations to achieve GHG levels
The U.S. Mayors’ Climate Protection Agreement commits to reducing greenhouse gas emission in participating communities by 7% below 1990 levels by 2012 through actions such as increasing energy efficiency, reducing vehicle miles traveled, maintaining healthy urban forests,
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reducing sprawl, and promoting use of clean renewable energy resources. It has been ratified by about 300 cities across the United States.
3.6.1.7 City of St. Helena On August 22, 2006, the City established a Climate Protection Task Force (Resolution 2006-112) to examine and recommend climate protection strategies for the City, local businesses, and residents. The Task Force has begun to study the goals of the U.S. Mayors’ Climate Protection Agreement to determine the local level of compliance and what actions are needed. The Task Force is also providing information to the public on global warming and how to reduce carbon emissions. This is available as a hands-on collection at the St. Helena Library on Library Lane or as an electronic library at http://city.ci.st-helena.ca.us/section.cfm?id=133.
3.6.2 Standards By itself, this project, or almost any project, will not produce a significant impact on global climate change. Amounts of carbon dioxide that produce measurable effects on the climate are in the millions of metric tons. However, the large climate effects we are now seeing are the product of many small contributions. Both globally and locally, amounts of greenhouse gases in the atmosphere are above the levels that create a significant environmental impact. Because legislation on climate change is recent, state standards for carbon dioxide emissions have not yet been adopted. This EIR uses the standard that any project that produces a net carbon contribution to the atmosphere is considered cumulatively significant.
Once the full regulatory structure for AB 32 is in place, it will be possible for projects to adhere to guidelines that will allow climate change impacts from the state as whole to less than significant. At that time, adherence to the regulatory structure will render an individual project’s impacts less than significant. This standard may apply to future maintenance actions if the No Project Alternative is selected.
3.6.3 No Project Alternative: Impacts and Mitigation Measures Description Under the No Project Alternative, the dam stays in place, and maintenance operations to clear sediments that accumulate behind the dam continue to occur periodically. Any single sediment clearing operation will have shorter duration than the proposed project; however, the on-going nature of the work will likely produce greater greenhouse gas emissions in total. Additionally, repeated clearing of the sediments means either that riparian vegetation will not have long enough to establish or that it will be periodically removed.
Impact GCC-NP1: On-going actions to remove sediment and debris will increase carbon dioxide by committing the City to repeated maintenance activities. (Potentially cumulatively significant and long- term)
Greenhouse gases are generated by use of construction equipment and trucks. Approximately half the construction equipment use and truck hauling for this project occur as part of sediment removal.
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Mitigation GCC-NP1: In the future, the City may be able to find contractors that use biodiesel fuels, which would reduce, but not eliminate, emissions. Additionally, adherence to regulations promulgated under AB 32 may render the action less than significant. However, there are too many unknowns to fully assess future impacts and mitigations under the No Project Alternative for global climate change.
Significance after Mitigation: Potentially significant and unavoidable.
3.6.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description The proposed project will produce GHGs from construction equipment and trucks moving dam and sediment materials to disposal locations. Under the Small Notch Alternative, trucks will be driving 17,910 miles (Corps 2006a). Heavy diesel trucks get 6-7 mpg. Each gallon of diesel generates 22 lbs. of CO2 (EPA 2005a). Direct estimation methods for the amount of carbon dioxide generated from the construction equipment is not available but should be roughly equivalent to the amount generated by truck use since it is likely to be the same number of construction vehicles as trucks (4 at a time), running for the same hours each construction day.
Impact GCC-PA1: Action alternatives will generate carbon dioxide. (Potentially cumulatively significant and short-term)
The project will generate approximately 55 metric tons at an average of 6.5 mpg. The project will also generate other GHGs, particularly nitrous oxide. (See construction emissions discussion in Section 3.2, Air Quality.) Mitigation measures recommended below will also sequester other GHGs, in proportion to the carbon dioxide sequestered (Miller, et al., 2004). Since calculations for emissions and sequestration of other GHGs are not as developed of carbon calculations, carbon dioxide emissions as representative of all GHGs are used herein.
Mitigation GCC-PA1: The project will use planting in the riparian areas to mitigate emission of GHGs by carbon sequestration. Sequestration of nitrous and sulfur oxides happen in parallel from the same plantings. Number and type of trees were estimated using the Corps’ Detailed Project Report Appendix C revegetation plan and the U.S. Department of Agriculture NRCS Riparian Forest Buffer planting recommendation of 400 trees per acre. The total number of trees planted for the Preferred Alternative is approximately 564. In order to measure success of this mitigation, the City shall monitor plant establishment as described in Section 3.3, Biological Resources.
Amount of carbon sequestered by the planting was calculated using the U.S. Department of Energy (US DOE) Urban Forestry Carbon Sequestration Worksheet. This method underestimates the total carbon sequestered because it assumes individual tree plantings, whereas this project will plant trees in riparian forest with dense herbaceous and shrubby understory, and it is anticipated that healthy leaf litter will develop. Both understory plantings and leaf litter enhance carbon sequestration. However, the alternate method designed for forest plantings does not include sufficient information on riparian species and habitat to generate accurate predictions. Use of the Urban Forestry Carbon Sequestration Worksheet was deemed
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adequate for this project because it means that mitigation measures will be more effective than the projections.
Carbon storage by 2020, established by AB32 and Executive Order S-3-05 as the year California will begin meeting GHG emission limits, will be 65 metric tons carbon dioxide equivalent. Since this amount is more than total project carbon dioxide emissions, the project will be a carbon sink rather than a carbon source. Plantings will continue to absorb carbon dioxide well into the future. In 2020, the project will be sequestering more than 8 metric tons as carbon dioxide. Therefore, the project impact to global warming, as mitigated, is beneficial.
Significance after Mitigation: Less than significant.
3.6.5 Full Dam Removal: Impacts and Mitigation Measures Description Full removal will create GHGs as described above in the Preferred Alternative. However, since the project is proportionally larger, there will be larger amounts of carbon dioxide and other GHGs released. Planting areas will also be larger under this alternative so more carbon dioxide can be sequestered.
Impact GCC-FR1: The project will generate carbon dioxide. (Potentially cumulatively significant and short- term)
Full dam removal generates approximately 45,000 cubic yards of material compared to the Small Notch Alternative’s approximately 40,000 cubic yards. This alternative is 12.5% larger for material moved than the Small Notch Alternative. Since carbon emissions are based on vehicle use to remove and place materials, emissions will be larger in the same proportion. The Full Dam Removal Alternative will produce 64 metric tons carbon dioxide.
Mitigation GCC-FR1: As specified in Mitigation GCC-PA1, use of the Corps’ planting plan shows that the Full Dam Removal Alternative will include planting approximately 636 trees of mixed species. The successful planting and establishment of these trees shall be monitored by the City as specified in Section 3.3, Biological Resources. This will sequester 72 metric tons of carbon dioxide by 2020 and will continue to sequester more than 9 metric tons a year. Therefore, the Full Dam Removal Alternative, as mitigated, has a beneficial impact on global warming.
Significance after Mitigation: Less than significant.
3.6.6 Fish Ladder: Impacts and Mitigation Measures Description The Fish Ladder Alternative will produce carbon dioxide over the long term as described in Impact and Mitigation GCC-NP1 and GHGs as described above in the Preferred Alternative. However, since the project is proportionally smaller, there will be lesser amounts of carbon dioxide and other GHGs released.
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The fish ladder will generate carbon dioxide from construction as described above in the Small Notch Alternative. However, since the project is proportionally smaller, there will be lesser amounts of carbon dioxide and other GHGs released. Additionally, the Fish Ladder Alternative includes the construction of a concrete fish ladder. Producing concrete also produces carbon dioxide. The production of concrete requires Portland cement; 0.9 metric tons of atmospheric carbon dioxide are generated for every metric ton of Portland cement produced (HVFAC 2005). Portland cement comprises 10 to 15% of the concrete. The fish ladder would be 23 feet long, consisting of 4-foot wide, 5-foot long, cast-in-place boxes on a concrete base. Engineering calculations for the volume or weight of concrete to be used in the fish ladder have not yet been done, but we estimate it will use roughly 600 cubic yards of cement.
Impact GCC-FL1: The project may generate carbon dioxide. (Potentially cumulatively significant)
The Fish Ladder Alternative generates approximately 19,000 cubic yards of dam and sediment material compared to approximately 40,000 cubic yards of material from the Small Notch Alternative, which is approximately 50% less. Therefore, the Fish Ladder Alternative will produce 28 metric tons carbon dioxide from general construction. The amount produced from concrete for the fish ladder cannot be calculated exactly because of current unknowns, including total volume of concrete and proportion of Portland cement, but it may contribute about 15-22 metric tons of atmospheric carbon dioxide. This alternative could generate 60 metric tons of carbon dioxide.
Mitigation GCC-FL2: As specified in mitigation GCC-PA1, use of the Corps’ planting plan shows that the Fish Ladder Alternative will include planting approximately 546 trees of mixed species. This will sequester 61 metric tons of carbon dioxide by 2020 and will continue to sequester more than 7 metric tons a year. Therefore, the Fish Ladder Alternative, as mitigated, has a beneficial impact on global warming.
Significance after Mitigation: Less than significant.
3.6.7 Section References Ackerman, A. and E. Stanton. 2006. Climate Change - The Costs of Inaction. Global Development and Environment Institute, Tufts University. October 11, 2006.
Adams, K. 2007. Thesis presentation on genetic variability in Oncorhynchus mykiss above and below permanent fish passage barriers. Sonoma State University. February 2007.
California Climate Change Center (CCEC). 2006. Our Changing Climate: Assessing the Risks to California. Union of Concerned Scientists, Scripps Institute of Oceanography, California Energy Commission, University of California, Berkeley, and California Air Resources Board. CEC-500-2006-077. July 2006.
Elsner, J. 2006. Evidence in support of the climate change – Atlantic hurricane hypothesis. Geophysical Research Letters. 33(16).
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Farrell, A., M. Hanemann, and C. Busch. 2007. Managing Greenhouse Gas Emissions in California. Chapter 10: Synthesis. The California Climate Change Center at UC Berkeley.
Grace, J. 2004. Presidential Address: Understanding and managing the global carbon cycle. Journal of Ecology. 92: 189-192.
High-Volume Fly-Ash Concrete Technology (HVFAC). 2005. Canadian International Development Agency, Natural Resources Canada, and Confederation of Indian Industry cooperative project. Accessed at: http://www.hvfacprojectindia.com/projects/backgrounds.htm
Intergovernmental Panel on Climate Change (IPCC). 2001. Climate Change 2001: Synthesis Report Summary for Policymakers. Working Group to the Third Assessment Report of the IPCC. Published for the Intergovernmental Panel on Climate Change. Cambridge University Press. New York, USA.
Intergovernmental Panel on Climate Change (IPCC). 2007. Climate Change 2007: The Physical Science Basis, Summary for Policy Makers. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, World Meteorological Organization and United Nations Environmental Programme. February 5, 2007.
Kerr, R, M., et al. Climate Change: Scientists Tell Policymakers We’re All Warming the World. Science. 315: 754. February 9, 2007.
Miller, P., R. Engel, and R. Bricklemyer. 2004. Soil Carbon Sequestration in Agriculture: Farm Management Practices Can Affect Greenhouse Gas Emissions. Dept. of Land Resources and Environmental Sciences, Montana State University Extension Service. MT200404 AG issued 4/04.
National Academy of Sciences (NAS). 2006. Understanding and Responding to Climate Change, Highlights of National Academies Reports. Climate and Global Change at the National Academies e-update, http://dels.nas.edu/global change. March 2006 edition.
Parmesan, C., and G. Yohe. 2003. A globally coherent fingerprint of climate change impacts across natural systems. Nature 421, 37–42.
Parmesan, C. 2006. Ecological and Evolutionary Responses to Recent Climate Change. Annual Review of Ecology, Evolution and Systematics. 37: 637-669.
Pew Center on Global Climate Change and Pew Center on the States. 2006. Climate Change 101, the Science and Impacts.
Stewart, R. 2007. Our Ocean Planet, Oceanography in the 21st Century. On-line textbook. Department of Oceanography, Texas A&M University. Copyright 2005. Last update February 14, 2007. Accessed at: http://oceanworld.tamu.edu/resources/oceanography- book/contents2.htm
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United Nations Framework Convention on Climate Change (UNFCC). 2006. National greenhouse gas inventory data for the period 1990-2004 and status of reporting. Item 3 (b) of the provisional agenda, National communication from Parties included in Annex I to the Convention. Subsidiary Body for Implementation, Twenty-fifth session, Nairobi, 6-14 November, 2006.
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California (DPR). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
U.S. Environmental Protection Agency (EPA). 2005a. Emission Facts: Calculating Emissions of Greenhouse Gases: Key Facts and Figures. EPA 420-F-05-003. February 2005.
U.S. Environmental Protection Agency (EPA). 2005b. Emission Facts: Metrics for Expressing Greenhouse Gas Emissions: Carbon Equivalents and Carbon Dioxide Equivalents. EPA 420- F-05-002. February 2005.
U.S. Environmental Protection Agency (EPA). 2006e. The U.S. Inventory of Greenhouse Gas Emissions and Sinks: Fast Facts. EPA 430-F-06-010. April 2006.
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3.7 Hazardous Materials 3.7.1 Setting There are two potentially significant sources of naturally-occurring hazardous materials that could result in adverse effects during construction at the Upper St. Helena Dam and Reservoir. The dam has naturally-occurring asbestos, and the sediments have naturally-occurring hydrogen sulfide (ITSI 2003). Both of these substances are relatively common in the local environment and do not pose a risk when they are in stable configurations in soil and rock. Potential risks arise when the area is disturbed and these compounds enter the air or water. Construction equipment and trucks also use toxic materials such as diesel fuel, oil, etc., which are common to all construction projects, and Best Management Practices (BMPs) exist to prevent potential problems.
The project will not introduce hazardous materials to the area except those associated with construction equipment. After construction, risks from naturally-occurring hazardous materials will be neither lower nor higher, as the project will not affect them. BMPs and mitigation measures during construction (described below and in Section 3.2, Air Quality) are designed to keep materials in place during site disturbance.
3.7.1.1 Asbestos Asbestos is a mineral consisting of thin, parallel fibers. Asbestos fibers do not dissolve in water or evaporate, and they are highly resistant to biological or chemical degradation. They can, however, enter water or air when the base material in which they are located decays or is disturbed. There are six kinds of asbestos: chrysotile, amosite, crocidolite, and the fibrous varieties of tremolite, actinolite, and anthophyllite (ATSDR 2001). Although all forms of asbestos can cause cancer or other diseases with sufficient exposure, chrysotile may be somewhat less hazardous than the other forms because the fibers are more pliable (ATSDR 2001). However, this point is currently under scientific debate. Hei, et. al., (1992) found that, while chrysotile fibers do break down more rapidly than other asbestos fibers inside living organisms, they still have significant cancer-causing potential.
Asbestos occurs naturally in asbestiform minerals, minerals with a fibrous texture from particles that occur in long, narrow strands. Asbestiform minerals often form in geologically active areas along fault zones and in subduction areas. In California, asbestiform minerals are largely present in the coastal ranges and Sierra foothills (EPA 2006d).
Minerals containing asbestos are amphibole, tremolite, and serpentine. Serpentine, a mineral formed in the subduction zones along the California coast, occurs in many California counties, including Marin, Sonoma, and Napa. Serpentine has a number of unique characteristics including the presence of chrysotile asbestos. Naturally-occurring asbestos is present in 44 of 58 California counties (OPR 2000).
Health Risks Exposure to airborne asbestos increases the risk of asbestosis, lung cancer, and mesothelioma (EPA 2006a). Asbestosis causes shortness of breath and impaired lung function as a result of scarring of the lung tissue. About one in 7 cases of asbestosis eventually develops into lung cancer (Monosson 1999). In addition to lung cancer, asbestos may contribute to lymphoma and
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cancer of the larynx, digestive tract, and kidney, although evidence on this point is not yet conclusive (NTP 2005). Mesothelioma is a cancer of the lining of the abdominal or chest cavities exclusively caused by asbestos exposure (Monosson 1999). Disease risks are related to the cumulative number of fibers inhaled and the time since first exposure (OEHHA 2003). Thus, both the duration and intensity of exposure are relevant to calculating health risks. Asbestos- related disease may not occur for decades after the causative exposure (CARB 2002).
In order to assess the cancer risk posed by asbestos that may become airborne from the project, the risk of a person maximally exposed by the project is compared to the background level of cancer for people in the area as a whole. The background level of cancer for people breathing the air in California is 760 in 1 million (CalEPA 2006).
The most intense asbestos exposure, and the most studied, is exposure in the workplace— workers engaged in manufacturing products that use asbestos or construction involving asbestos materials such as insulation. However, widespread manufacturing and use of asbestos products has generated elevated background levels of asbestos across the United States. The entire population is potentially exposed to some degree; however, the potential for exposure continues to decline because asbestos mining has stopped, and products containing asbestos are being eliminated from the market (NTP 2005). Currently, the risk of mesothelioma from background asbestos exposure is 1 or 2 individuals in 1 million people (OEHHA 2003).
Lung cancer background levels are higher because of smoking and other airborne carcinogens. Background asbestos may come from human sources such as release from building materials and vehicle brake linings. It may also come from naturally-occurring asbestos that is released through mining and other ground-disturbing activities or the natural erosion of asbestos- containing soils and rocks (Bourdes, et al., 2000). Studies on non-occupational or occasional asbestos exposure indicate that brief high exposure incidents raise the risk of asbestos=related disease more than very low level, long-term exposure (ATSDR 2001).
Project Area The bedrock in the project area is a shale/serpentinite mélange, and area soils may have high serpentine content (Corps 2006a). The dam is constructed of local rock and soil. The dam has been sampled for asbestos at 4 locations. Two borings were performed and samples were taken from two different levels in each of the borings. Asbestos was not detected at 2 of the sites and composed 2.8% and 3.5% of material at the other 2 sample locations (ITSI 2003). This is consistent with the likely inclusion in the dam of some serpentine rocks from the surrounding area. Assuming that these samples are representative of the dam as a whole, the dam is about 1.6% asbestos from serpentine. Additionally, soils and rock beneath reservoir and dam may be serpentine. Chrysotile asbestos from serpentine could potentially become airborne through construction activities.
3.7.1.2 Hydrogen Sulfide The upper reservoir has a deep layer of sediment. Anaerobic bacteria live in aquatic sediments in ponds, marshes, lakes, streams, and rivers and anywhere that flow rates are low enough to allow sediment to accumulate. These bacteria produce hydrogen sulfide as a by-product of their metabolism. Hydrogen sulfide is a colorless, heavier than air gas with a smell of rotten eggs. Under normal conditions of the system, the hydrogen sulfide remains within the sediments
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where it was generated and does not pose a hazard. It can constitute a risk to human health if it becomes airborne.
Hydrogen sulfide is a neurotoxin that can cause eye and nose irritation, headaches, dizziness, nausea, and eventually unconsciousness and death at concentrations from 100 to 1,000 parts per million (ppm). It is first detectable by smell at 0.7 ppm (Stultz and Collar 1993). However, odor cannot be used as a reliable warning because high concentrations, or continuous exposure to low levels, cause olfactory fatigue (ATSDR 2006).
3.7.1.3 Arsenic Sampling of the sediments in the upper reservoir revealed arsenic at levels ranging from 1.0 to 3.6 mg/kg (ITSI 2003). ITSI compared their metal results with the EPA Region 9 Preliminary Remedial Goals (PRG) and reported arsenic in exceedance of the standard. The PRG standard for direct contact industrial soils (cancer endpoint) is 1.6 mg/kg. If exposures are not long-term, the relevant standard would be the noncancer endpoint PRG, which is 260 mg/kg (EPA 2004). PRG standards are advisory, not site specific. Further, the PRG standards are designed to guide clean up of contaminated sites. The average arsenic in California soils is 5.5 mg/kg (ITSI 2003). Therefore, the average native soil has higher arsenic concentrations than those naturally- occurring in the sediments at the upper reservoir. Since arsenic and other metals at the site are naturally-occurring and consistent with the amount in other soils, they do not pose a hazard.
3.7.1.4 Vehicle-Associated Toxics In addition to naturally-occurring hazardous substances, the project will utilize the normal hazardous materials that occur in all construction: gasoline, oil, coolant, and other hazardous materials associated with vehicle use. Significant quantities of pollutants are not expected to be present in storm water discharges from the site. However, precautions will be taken to prevent toxics from entering the waterway and causing adverse impacts to aquatic life. These consist of standard construction BMPs, together with some special precautions for riparian areas, and preparation of a Storm Water Pollution Prevention Plan (SWPPP) utilizing guidelines from the State Water Resources Control Board that will be followed during construction activities.
The key to keeping potentially hazardous construction materials out of storm water is to perform most of the construction during the dry season, generally between June 15 and October 15. Additionally, the site will be dewatered so that construction vehicles are not in the flow of York Creek. (See Section 3.3, Biological Resources, for further details regarding dewatering.) Specific measures to prevent adverse impacts from construction vehicles are given in Mitigation Haz-NP2 below.
3.7.1.5 Regulatory Setting The federal Environmental Protection Agency (EPA) regulates asbestos under the Clean Air Act and the Toxic Substances Control Act. State and local air boards must set standards to comply with these regulations. The federal Occupational Health and Safety Administration (OSHA) regulates workplace exposure to asbestos. They have delegated authority to 24 states including California.
In California, authority is delegated to the Department of Industrial Relations, Division of Occupational Safety and Health (DOSH). DOSH operates the Cal/OSHA enforcement unit,
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which enforces California's Asbestos Standards in Construction (8 CCR §1529), Shipyards (8 CCR §8358), and General Industry (8 CCR §5208). This project would be regulated under CCR §1529 (g): “Excavation which may involve exposure to asbestos as a natural constituent which is not related to asbestos mining and milling activities.” Project activities qualify as Type II asbestos work: removal of asbestos-containing material (ACM) that is not insulation or surfacing material.
Additionally, the Bay Area Air Quality Management District (BAAQMD) regulates construction activities in areas with naturally-occurring asbestos under the Asbestos Airborne Toxic Control Measure (ATCM) for Construction, Grading, Quarrying, and Surface Mining Operations (BAAQMD 2007b). BAAQMD sets trigger levels for toxic air contaminants (TACs) from new sources below which the TAC is not expected to pose a risk to the public. Hydrogen sulfide acute trigger level is 0.093 pounds per hour, and the chronic trigger level is 390 pounds per year (BAAQMD 1999a). See Section 3.2, Air Quality, for more details on asbestos and hydrogen sulfide regulations.
3.7.2 Standards The major potential for hazards from naturally-occurring substances at the project site is to construction workers who will be the maximally exposed individuals. Therefore, standards for significant impact are taken from OSHA regulations to protect construction workers. OSHA sets the following Permissible Exposure Limits (PELS).
Table 14. OSHA Permissible Exposure Levels
Substance Time Weighted Average (TWA) Excursion Limit Asbestos 0.1 fiber/cm3 over 8 hours 1.0 fiber/cm3 over 30 (airborne concentration) (29 CFR 1926.1101(c)(2)) minutes (29 CFR 1926.1101(c)(2)) Hydrogen Sulfide 20 ppm 50 ppm 10 minutes (29 CFR 1910.1000, Table Z-2) maximum (29 CFR 1910.1000, Table Z-2)
Additionally, areas with ultramafic or serpentine soils are presumed to have asbestos, unless proven otherwise, and work in such areas is considered a significant impact requiring mitigation practices during construction (BAAQMD 1999a).
Vehicle toxics release would be considered significant if it caused adverse impacts to beneficial water uses.
This section addresses the risks to human health from airborne asbestos and hydrogen sulfide, which provide the main human health effect. The affects of aquatic asbestos and hydrogen sulfide are assessed in Section 3.11, Water Quality.
3.7.3 No Project Alternative: Impacts and Mitigation Measures Description The No Project Alternative will leave the dam in place. Asbestos from the dam will not be released. However, sediments will need to be removed periodically for on-going maintenance.
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The potential for release of hydrogen sulfide and for water contamination will be largely the same for the maintenance activities and each of the action alternatives. The only difference is that sediment removal impacts will be repeated periodically with the No Project Alternative.
Impact HAZ-NP1: Potential for exposure of construction workers to unsafe levels of hydrogen sulfide. (Potentially significant and short-term)
Hydrogen sulfide pockets may be opened during sediment excavation, leading to unsafe exposure of construction workers. In previous sediment maintenance operations, workers have smelled hydrogen sulfide but not suffered health consequences. However, the amount of hydrogen sulfide being released will vary because it is not uniformly distributed through the sediments. It is not anticipated that levels will be high enough to generate more than nuisance odor; however, since the level of hydrogen sulfide is unknown until construction takes place, mitigation shall be implemented to make sure that this is not a significant effect.
Maintenance dredging of the reservoir is essentially the same activity as sediment removal prior to dam removal. As such, the No Project Alternative involves repeated impacts as dredging occurs. Depending on the frequency of dredging, concentrations of hydrogen sulfide may be lower in routine dredging than in any of the project alternatives. However, because of the uneven distribution of the hydrogen sulfide, maximum concentrations may be the same. Because toxic effects of high levels of hydrogen sulfide can happen in a matter of seconds, it is peak rather than averaged concentration that is important in assessing impacts.
Mitigation HAZ-NP1: A portion of construction workers, at least one in each area, shall wear a personal safety hydrogen sulfide monitor. If levels exceed OSHA safety standards, construction will be halted, and the vicinity cleared until the hydrogen sulfide gas has time to dissipate.
Significance after Mitigation: Less than significant.
Impact HAZ-NP2: Potential for standard toxics associated with construction vehicle operation to be released into the environment. (Potentially significant and short-term)
All construction that happens in riparian zones creates possible water contamination from construction vehicle leaks. The longer the construction lasts, and the larger the area affected, the greater the risk. BMPs are required by CDFG and the Regional Water Quality Control Board as part of their permits (§1602 and §401, respectively) for projects in environmentally sensitive areas. These practices have been repeatedly shown to be effective at preventing water contamination. The same BMPs will be required for either maintenance or the action alternatives.
Mitigation HAZ-NP2: Release of toxics shall be avoided by use of BMPs listed below. The City, or designated contractor, shall include these measures as part of project implementation:
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Construction Equipment and Vehicles • Maintain all construction equipment to prevent oil or other fluid leaks. Use drip pans for any oil or fluid changes that are required for maintenance of equipment. Keep vehicles and equipment clean. Do not allow excessive build-up of oil and grease. • Use off-site repair shops as much as possible. • Always use secondary containment, such as a drain pans or drop cloths, to catch spills or leaks when removing or changing fluids. • Place stockpiled spill cleanup materials where they will be readily accessible. Regularly inspect on-site vehicles and equipment for leaks, and repair immediately. Check incoming vehicles and equipment (including delivery trucks and employee and subcontractor vehicles) for leaking oil and fluids. Do not allow leaking vehicles or equipment on-site. • Segregate and recycle wastes, such as greases, used oil or oil filters, antifreeze, cleaning solutions, automotive batteries, and hydraulic and transmission fluids. • Use off-site fueling stations as much as possible. • If fueling must occur on site, use designated areas located away from drainage. Locate on-site fuel storage tanks over a retention area designed to hold the total tank volume. • Discourage "topping-off" of fuel tanks, as it frequently leads to fuel spillage. • Avoid mobile fueling of mobile construction equipment around the site; transport the equipment to designated fueling areas. • Adhere to the SWPPP for the project site.
Storage • Vehicle and equipment storage, cleaning, and maintenance areas shall be established in designated, confined areas. These areas should be located away from significant drainage courses and out of the riparian corridor to the extent feasible. Cleaning and maintenance activities shall be allowed only in such designated areas. • Direct any concentrated storm water run-on/runoff around storage and service areas. Minimize contact of storm water and run-on/runoff with stored equipment by raising equipment on pallets or other similar devices.
Impact after Mitigation: Less than significant.
3.7.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description To open a small notch in the dam, approximately 12,000 cubic yards of dam material and 830 cubic yards of downstream material will be removed. Implementation of all the action alternatives, including the Preferred Alternative, may result in potential impacts from hydrogen sulfide and vehicular toxics as discussed in the No Project Alternative (HAZ-NP1 and HAZ- NP2), except that Preferred Alternative impacts will be reduced because no follow-up sediment
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removal will be necessary. Mitigation measures described in the No Project Alternative will be implemented to reduce impacts to a less than significant level (Mitigations HAZ-NP1 and HAZ- NP2).
When material from the dam is removed to create the notch, it is possible that serpentine rocks will be broken open and serpentine soils exposed to the air and dried. Both of these can release friable chrysotile asbestos into the atmosphere. This additional potential impact and mitigation are described below.
Impact HAZ-PA1: Asbestos may become airborne through earthmoving activities during dam removal creating a health hazard for construction workers. (Potentially significant and short-term)
Asbestos may become airborne during the removal of materials from the dam. Particles may remain airborne for two or more weeks, but they will gradually settle and be dispersed by the wind. Areas with serpentine soils have somewhat elevated asbestos levels in general. It is unlikely that the project will generate sufficient asbestos to have health impacts to the surrounding region. However, if airborne asbestos is sufficiently high at the upper reservoir site, there could be deleterious health impacts to the construction workers.
Many factors could affect the level of airborne asbestos produced by construction, including the distribution of serpentine pockets within the dam, the character of the soils, the timing of the different components of construction, humidity and wind on construction days, and possibly other confounding factors. There are too many unknowns to create a justifiable estimate of asbestos levels during construction (Ghezavat 2007). Instead, it is reasonable to presume that significant impacts may occur and implement preventative mitigation.
Mitigation HAZ- PA1: In order to protect the health of construction workers, in accordance with OSHA regulations and guidance, the City shall: • Train construction workers regarding asbestos hazards and self-protection. • Perform air-monitoring. The monitoring program shall be designed and overseen by a “competent person” as defined in 29 CFR §1926.1101(b). In the event that air monitoring shows levels in exceedance of PELS or excursion level limits, the competent person shall require respiration equipment or other measures necessary to protect worker health. • Designate and demark a “regulated area” around the dam removal site, following the recommendations of the competent person. Only authorized personnel may enter the regulated area. Workers must use appropriate hygienic practices within the regulated area including not eating, drinking, or smoking and wearing disposable coveralls. • Prevent asbestos from becoming airborne by use of water and other BMPs. The City shall adhere to the BAAQMD practices for mitigating asbestos risk as stated in Section 3.2, Air Quality, Mitigation AIR-NP3.
Before construction, in accordance with the naturally-occurring asbestos ATCM (CCR Title 17, §93015), the City shall get an Asbestos Dust Mitigation Plan Application approved for specific measures that will effectively control dust for the particular project and site. Measures will include at least one action from each category.
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Materials placed off site at the lower reservoir will be secured in place with both 3 inches of non-asbestos-containing soil and vegetative planting above the expected average water level of the reservoir. Dam materials will not be transported to Spring Mountain Vineyard or Clover Flat landfill.
Significance after mitigation. Less than significant.
3.7.5 Full Dam Removal: Impacts and Mitigation Measures Description The Full Dam Removal Alternative will generate approximately 16,000 cubic yards of dam material and 1,025 cubic yards of downstream material. Implementation of full dam removal may have potential impacts from hydrogen sulfide and vehicular toxics as discussed in the No Project Alternative, except that the Full Dam Removal Alternative impacts will be reduced because no follow-up sediment removal will be necessary. Asbestos impacts could be similar to those described for the Preferred Alternative, or even larger because more material will need to be removed. Mitigation measures described in the No Project Alternative and Preferred Alternative sections will be implemented to reduce impacts to a less than significant level (Mitigations HAZ-NP1, HAZ-NP2, and HAZ-PA1).
3.7.6 Fish Ladder: Impacts and Mitigation Measures Description The Fish Ladder Alternative calls for the smallest amount of earthmoving, both from the dam and from the sediments. Under this alternative, about 10,000 cubic yards of sediment and 8,500 cubic yards of dam material will need to be moved. The substrate underneath the dam and sediments will not be affected. With less material being moved, a smaller potential amount of both asbestos and hydrogen sulfide could become airborne. Still, there may be potential impacts from asbestos and hydrogen sulfide. Vehicle hazardous materials impacts are the same as in Impact Haz-NP1 above. Mitigation measures described in the No Project Alternative and Preferred Alternative sections will be implemented to reduce impacts to a less than significant level (Mitigations HAZ-NP1, HAZ-NP2, and HAZ-PA1).
3.7.7 Section References Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service. Toxicological Profile for Asbestos. 2001.
Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service. Medical Management Guidelines for Sulfur Dioxide. CAS #7446-09-05. UN# 1079. Accessed at: http://www.atsdr.dcd.gov/mhmi/mmg116.html
Bay Area Air Quality Management District (BAAQMD). 1999a. BAAQMD CEQA Guidelines: Assessing the Air Quality Impacts of Projects and Plans. Prepared by the Planning and Research Division of the Bay Area Air Quality Management District. December 1999.
Bourdes, V., P. Boffetta, and P. Pisani. 2000. Environmental exposure to asbestos and risk of pleural mesothelioma: review and meta-analysis. European Journal of Epidemiology 16:411-417.
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California Air Resources Board (CARB). 2002. Naturally-Occurring Asbestos General Information. California Environmental Protection Agency. Accessed at: http://www.arb.ca.gov/toxics/asbestos/general.htm
California Environmental Protection Agency (CalEPA). 2006. A Guide to Health Risk Assessment. Office of Environmental Health Hazard Assessment, California Environmental Protection Agency.
Ghezavat, Sam. 2007. CalOSHA, Industrial Hygiene Engineer. Personal communication. February 8, 2007.
Hei, Tom K., et al. 1992. Chrysotile Fiber is a Strong Mutagen in Mammalian Cells. Cancer Research. 52:6305-6309. November 15, 1992.
Innovative Technical Solutions, Inc. (ITSI) 2003. Final Report: HTW Assessment, Upper York Creek Ecosystem Restoration Project, St. Helena, California. Prepared for U.S. Army Corps of Engineers, San Francisco District. December 2003.
Monosson, Emily, Ed. 1999. Asbestos Health Hazards. Encyclopedia of Earth. Accessed at: http://www.eoearth.org/article/Asbestos_health_hazards
National Toxicology Program (NTP). 2005. Substance Profiles: Asbestos CAS No. 1332-21-4. Report on Carcinogens, Eleventh Edition. U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program.
Office of Environmental Health Hazard Assessment (OEHHA). 2003. Asbestos Fact Sheet. State of California.
Office of Planning and Research (OPR). 2000. Memo From: Terry Roberts, Senior Planner Governor's Office of Planning and Research, Re: Addressing Naturally Occurring Asbestos in CEQA Documents. California State Clearinghouse. October 26, 2000. Accessed at: http://www.opr.ca.gov/clearinghouse/asbestos.html
Schultz, Tom and C. Collar. Dairying and Air Emissions. University of California Cooperative Extension Dairy Manure Series. UCCE-DMMS-4. October 1993.
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California (DPR). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
U.S. Environmental Protection Agency (EPA), Region 9. 2004. PRG 2004 Table. Accessed at: http://www.epa.gov/region09/waste/sfund/prg/index.html
U.S. Environmental Protection Agency (EPA). 2006a. Asbestos and Vermiculite: Basic Information. October 18, 2006. Accessed at: http://www.epa.gov/asbestos/pubs/help.html#Info
U.S. Environmental Protection Agency (EPA). 2006d. Region 9: Naturally Occurring Asbestos (NOA) in California. August 23, 2006. Accessed at: http://www.epa.gov/region09/toxic/noa/.
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3.8 Hydrology and Hydraulics 3.8.1 Setting Introduction This section describes the existing hydrology, geomorphology, and sediment transport resources of York Creek in the Upper York Creek Ecosystem Restoration Project sites and project area. Potential impacts of the proposed project alternatives on those resources are described, and mitigation measures to eliminate or minimize potentially significant impacts imposed by the project are discussed. For the purposes of this section the project sites include Upper York Creek Dam and Reservoir (UYCD) and Lower York Creek Reservoir (LYCR). Spring Mountain Vineyard and Clover Flat landfill are not included in the discussion as there are no hydrologic or hydraulic concerns at these proposed sediment disposal sites. The project area includes York Creek and its adjacent floodplain from UYCD to its confluence with the Napa River.
Department of Water Resources (DWR) and the U.S. Army Corps of Engineers (Corps) have performed hydrologic and hydraulic analyses of the proposed project at the UYCD project site (DWR 2002a, 2002b, Corps 2005). Prunuske Chatham, Inc. (PCI) conducted a hydrology and hydraulics study of lower York Creek in 2006 (PCI 2007a) to assess potential impacts to the channel and flooding as a result of removing UYCD and reestablishing natural sediment transport processes in the project area. A GIS-based hydrologic model of the watershed was produced using HEC-HMS and hypothetical frequency-based precipitation events for the region. Peak stream flows were computed from the hydrologic model and routed through the lower 1.5 miles of lower York Creek using HEC-RAS, a one-dimensional hydraulic model. Flooding history and sediment distribution data was collected for this lower reach. Water surface elevations and sediment transport potential were calculated at 44 surveyed cross sections.
As a result of on-going data collection and analyses to support the City of St. Helena in the Upper York Creek Ecosystem Restoration Project, PCI surveyed the reservoir topography in 2004, 2005, and 2006. Estimates of reservoir volume and sediment deposition rates were calculated using these surveys in combination with historic data (City of St. Helena 1932; Albion 1993, 2002). In addition, sediment sampling of both reservoir and upstream channel deposits in 2005 and 2007 provide data on grain sizes transported annually in upper York Creek.
In several instances there are discrepancies between data values cited in Corps documents and PCI calculations. Unless otherwise stated, the latter are used in this report.
Project Area York Creek flows from the eastern flank of the Mayacmas Mountains of the California Coast Range to the Napa River on the northeast edge of St. Helena. It drops approximately 2,000 feet over it 7.24-mile length (Corps 2006b). The headwaters of York Creek drain steep, forested slopes underlain by highly erodible metamorphic, volcanic, and sedimentary rocks. Land use in the upper watershed consists primarily of ridgetop vineyards. Other than UYCD and Spring Mountain Road, the upper reaches of the creek have seen little modification. Downstream of UYCD, in the middle reach, the creek flows through a narrow, confined alluvial valley bordered by sparse residential housing. After exiting the foothills, York Creek traverses the Napa Valley’s
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alluvial plain for 0.85 miles. Land use in the lower reach is a mixture of dense residential, commercial, and agricultural-industrial. The creek is bordered by vineyards along much of this reach. Through the City of St. Helena, York Creek has been modified through riparian vegetation removal, bank hardening, levee construction, and bridge placement (Corps 2006a). The last 0.4 miles has been straightened and channelized.
Project Sites Upper St. Helena Dam is located 1.25 miles northwest of the City of St. Helena and is 50 feet tall and stretches 140 feet across the channel (Corps 2006a). Flow coming into the reservoir is concentrated to a drop-inlet snorkel located just behind the face of the dam. The snorkel is a perforated pipe that connects to a masonry-lined tunnel that passes through the dam and releases water on the downstream side into a small pool. During periods of high flows, a spillway located on the left side of the reservoir (looking downstream) parallel to Spring Mountain Road takes water approximately 100 feet downstream of the dam directly to York Creek. Steep hillslopes and Spring Mountain Road create a narrow channel for York Creek in the project reach.
UYCD was built to store 10 million gallons (~30 acre-feet) of water to supply the growing town of St. Helena (Corps 2006a). Use of the reservoir for water storage and supply was halted due to sedimentation issues. Regular clearing of accumulated sediment for dam maintenance is necessary every 5-20 years, with the last excavations occurring in 1992 and 2006. Prior to sediment removal activities in 2006, the storage capacity of the Upper York Creek Reservoir was at less than 50% due to sediment accumulation (PCI 2007a).
Lower York Creek Reservoir is an off-stream impoundment located 0.5 miles down Spring Mountain Road from UYCD. The 160 acre-foot capacity reservoir was originally constructed to provide water for domestic and fire protection uses. Currently, the water stored in the reservoir is untreated and utilized for irrigation and construction activities.
Hydrology Average annual rainfall in the York Creek watershed ranges from 35 to 40 inches (Corps 2006a, citing Lambert and Kashiwagi 1978). Record 7-day precipitation totals occurred during the week of December 24, 2005, to January 3, 2006, when rainfall in the area ranged from 18.5 to 29.6 inches (Parrett and Hunrichs 2006). Approximately 7 of those inches fell in one 24-hour period producing the largest flood on record for the watershed – the 2005 New Year’s Eve Flood.
York Creek does not have a historic stream flow-gaging station. The Napa County RCD established a gage at the Highway 29 Bridge in 2005. Unfortunately it was disabled by debris on December 30, 2005, and did not capture the peak flow event the next day. To synthesize peak stream flows in York Creek, hypothetical frequency storms were used as input to HMS models (Corps 2005; PCI 2007a). Hypothetical frequency storm events are statistically derived and are based on the probability of occurrence in a given area for a given time period (Table 15).
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Table 15. Statistically Derived Rainfall Intensities Used to Estimate Peak Stream Flow for the Given Return-Period Storm Event. Rainfall Depth Duration Frequency (inches) Return Period (years) 15 min 1 Hr 2 Hr 3 Hr 6 Hr 12 Hr 24 Hr 2 0.27 0.60 0.90 1.17 1.82 2.64 3.73 10 0.38 1.01 1.52 1.97 3.05 4.43 6.26 25 0.54 1.21 1.82 2.37 3.67 5.33 7.52 50 0.61 1.36 2.05 2.66 4.13 5.98 8.45 100 0.67 1.51 2.27 2.94 4.57 6.63 9.37 (PCI 2007a)
The 2005 New Year’s Eve (NYE) storm was reported regionally to be a 25 to 50-year event by the USGS (Parrett and Hunrichs 2006). Hydrologic modeling of the watershed using measured precipitation totals indicates that the stream flow produced by the 2005 NYE storm was slightly greater than that of a 25-year recurrence interval storm (PCI 2007a). Table 16 lists the discharges determined by the watershed models for the standard flow recurrence intervals. The recurrence interval is the average length of time between flood events of a given magnitude. More accurately, a peak discharge with a 25-year recurrence interval has an annual exceedance probability of 4%, or the probability of a storm of that magnitude or greater occurring in any given year is 0.04 or 4%.
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Table 16. York Creek Peak Stream Flows associated with Standard Recurrence Intervals at Several Locations in the Watershed.
PCI 2007 Study USACE Flows 2005 Existing Upper Dam Study Conditions* Removed
Just below Upper Reservoir Drainage Area (mi2) 2.48 2.39 2.39 115 235 240 50% AEP - Q2 420 605 605 10% AEP - Q10 700 860 860 4% AEP - Q25 2005 NYE event n/a 890 900 960 1220 1220 2% AEP - Q50 1280 1550 1550 1% AEP - Q100
At Napa River Drainage Area (mi2) 5.01 4.40 4.40 295 440 455 50% AEP - Q2 960 1030 1040 10% AEP - Q10 1440 1440 1450 4% AEP - Q25 2005 NYE event n/a 1500 1530 1850 1915 1930 2% AEP - Q50 2310 2400 2410 1% AEP - Q100
Note: All peak flows are in cubic feet per second. AEP - Annual Exceedance
Probability. NYE - 2005 New Year's Eve. Q# denotes average recurrence interval in years.
* - Assumes a cleaned out condition of the Upper Reservoir for AEP calculations and a real "full of sediment condition" for NYE event
The 2005 NYE storm event caused flooding and property damage in lower York Creek. Flows exceeded channel capacity and flooded the Beringer Winery warehouse, administrative building, parking lots, and vineyards, as well as the Culinary Institute’s dorms and several downstream vineyards. York Creek also overtopped its banks in several locations between Spring Mountain Road Bridge and Highway 29 (Figure 11). Hydraulic model results indicate that the “base flood” or 100-year storm event will cause widespread flooding throughout lower York Creek within the City limits. Flooding occurs at bankfull flows (Q2) in one location adjacent to the Beringer Winery warehouse.
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Geomorphology York Creek is predominantly classified as a moderately entrenched, riffle dominated, relatively stable, gravel/cobble substrate channel (Figure 12) (NCRCD 2005). Channel features were measured in a reach upstream of UYCD, which represents natural stream conditions, to determine average channel width, as well as pool and riffle lengths (Corps 2006a, Appendix A citing Entrix 2002; PCI 2007a). Average pool and riffle lengths are 105 and 128 feet, respectively (Corps 2006a, Appendix A). PCI measured channel widths range 20-25 feet. In the lower reaches where the channel is not so constrained by the steep valley walls, the planform begins to meander, and a pool/riffle structure occurs (Figure 13). Through the City, York Creek maintains a fairly consistent width and depth except for one location adjacent to the Beringer Winery warehouse where a large gravel/cobble bar has formed and filled the channel (Figure 14).
Sediment Transport The area above the dam represents 55% of the total watershed and 63% of the steep, sediment- source zone. The reservoir captures the entire coarse bedload and a portion of the suspended load produced in its 4.4 square mile drainage area – approximately 1,000-5,000 cubic yards of material annually depending on the rainfall and runoff patterns. An average hydrologic year with no unusual storm events delivers roughly 1,250 cubic yards of sediment to the reservoir. The winter of 2005/2006, an above-average year with the largest storm in recent history, deposited approximately 3,000 cubic yards of material behind the dam.
Throughout the watershed, the channel bed is composed of sediment ranging from sand to small boulders. The mean grain size is consistently very coarse gravel (32-64mm) to small cobble (64-128 mm), with low percentages of fines in the deposits (NCRCD 2005, PCI 2007a). Sediment deposited in the upper reservoir ranges from silt to small cobbles. Forty-one percent of the material by weight is made up of fine sediment (<2 mm) transported as wash and suspended load, while 30% is bedload composed of coarse gravel (16 mm) and larger particles.
Regulatory Environment The upper watershed, including UYCD, is located within unincorporated Napa County. The lower reaches of York Creek are within the limits of City of St. Helena. The upper dam property, structure, and right-of-way were purchased by the City of St. Helena in 1922 (Corps 2006a). The City of St. Helena has the only pre-1914 appropriative rights to York Creek.
The City of St. Helena’s Municipal Code Title 15, Chapter 15.52 Flood Damage Prevention provides for the establishment of areas of special flood hazard through scientific studies and mapping, as recommended by the City floodplain administrator. The floodplain administrator has the responsibility to manage activities that affect flooding and maintain the carrying capacity of channels within, or affecting properties within, City limits.
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Figure 11. Approximate Locations of Overbank Flows in Lower York Creek. Based on flood recurrence interval (as listed in Table 16). Locations marked for the 25-year flow and lower experienced out-of-bank flows during the 2005 NYE storm event.
Figure 12. Characteristics of the Upper Watershed Channels. Characteristics include high slopes, steep riffles, and alternating gravel/cobble bars.
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Figure 13. The York Creek Channel through the City of St. Helena. The channel is less confined by valley walls. Bed material is coarse, as most of the sediment produced by the upper watershed is trapped in the upper reservoir.
Figure 14. Aggraded Channel in the Beringer Winery Reach. Flooding occurs approximately every 2 years at this location.
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3.8.2 Standards Significance criteria for hydrology and water resources are outlined in the CEQA Checklist from Appendix G of the CEQA Guidelines. The project alternatives have been evaluated and significant impacts determined based on if they would:
• Cause streambank erosion or long-term streambed aggradation/ degradation resulting in damage to private property, utilities, or infrastructures. • Increase flood hazards through flow diversion or obstruction, or change the rate and/or amount of runoff. • Increase the risk of loss, injury, or death involving flooding, including flooding as a result of the failure of a levee or dam. For the purposes of this EIR, the determination of significance is based on the above-mentioned guidelines, as well as policies set forth by the County’s General Plan and other documents as referenced. Environmental impacts associated with the proposed project alternatives are discussed below. Impacts are classified as significant, potentially significant, or less than significant. Mitigation measures are provided whenever possible to avoid or reduce the impact to less than significant.
3.8.3 No Project Alternative: Impacts and Mitigation Measures Description Under the No Project Alternative, UYCD would not be altered from its current configuration, and no ecosystem restoration measures would be implemented. The dam would remain as an unnatural channel barrier, and the majority of sediment delivered from the upper watershed would continue to deposit in the reservoir. Maintenance dredging would be required on a regular basis to manage the sediment accumulation behind the dam. Historically, this has occurred every 5-20 years, with the timing determined by sediment accrual rate and its elevation around the drop-inlet structure. Under the No Project Alternative, sediment disposal and/or reuse sites would be selected on an as needed basis.
Releases of detrimental amounts of fine sediment were documented by the Department of Fish and Game four times between 1965 and 1992 (Corps 2006b). These releases were likely associated with reservoir maintenance activities during low flow periods and resulted in fish kills and impairment of downstream aquatic habitat. Details on the impacts and mitigation measures associated with fine sediment releases from reservoir maintenance can be found in the Biology (Mitigation BIO-NP3) and Water Quality (Mitigation WQ-NP1) resource sections of this document.
UYCD does not have the flow control structures to operate as a flood control structure. Even if these structures were installed, the maximum impoundment is only 27 acre-feet. The 2-year storm event produces five times the volume of water needed to fill the reservoir’s base pool volume. Filling of the reservoir pool delays the storm peak by 20 minutes and reduces it by 5 cfs (PCI 2007a). For larger, less frequent storm events, there is no difference between peak discharges with or without the dam in place, as measured immediately below UYCD. Thus, early runoff during a storm event quickly fills the pool, and subsequent flows pass through the
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spillway and drop-inlet. The hydrologic model of UYCD indicates that even during the 100-year storm event, the dam is not overtopped (PCI 2007a).
The dam itself was constructed in 1900. A concrete spillway was added in 1933, and minor modifications occurred in 1985 and 1993. It is an earthen dam composed of approximately 12,000 cubic yards of local fill material faced with basaltic fieldstone riprap. The dam is resting on serpentine bedrock that exhibits varying degrees of strength within the project site (Corps 2006a). UYCD has not been evaluated for seismic stability.
Impact H&H-NP1: On-going sedimentation of the Upper York Creek Reservoir may threaten dam functioning and stability. (Potentially significant and long-term)
Aggradation of the streambed within the reservoir area occurs annually. During an average hydrologic year, 1,000 to 1,500 cubic yards of coarse sediment are deposited behind the dam. Twice that amount can be deposited during large storm events, such as the 2005 New Years Eve storm (Corps 2006a; PCI 2007a). Long-term aggradation restricts, and may completely obstruct, the drop-intake structure, reducing the volume of stream flow that the dam is capable of bypassing during high flow. A fully aggraded reservoir may increase the likelihood of overtopping and failure.
Mitigation H&H-NP1: To avoid threats to dam safety and function, the City shall continue the regular removal of aggraded sediment in the reservoir. It is expected that sediment removal will be needed on a 10 to 20-year cycle in perpetuity. Actions required to maintain UYCD and ensure its hydrologic functioning are: • Annual monitoring of sediment levels in the reservoir. • Annual maintenance of the drop-intake structure and spillway to clear debris or other obstructions. • Timely implementation of sediment removal projects that incorporate environmental compliance mitigation measures listed under the other resource impact sections in this EIR.
Significance after Mitigation. Less than significant.
Impact H&H-NP2: Failure of Upper St. Helena Dam could result in loss of life, property damage, and/or streambed aggradation. (Potentially significant and long-term)
Catastrophic failure of Upper St. Helena Dam from overtopping, earthquake, or other unforeseen event is a possibility. Based on its age and construction, it is unlikely that it conforms to seismic design code and would require retrofit measures to bring it to modern safety standards. Although hydrologic models of the predicted 100-year rainfall event do not indicate that the dam would be overtopped, it is possible that watershed and rainfall conditions could occur that would lead to overtopping and erosion of the dam fill. This potential flood
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event has an annual exceedance probability of less than 1%, is larger than the base flood (100- year event), and thus typically does not require mitigation measures.
A dam-break inundation map was produced for the City of St. Helena (Hanson). This map indicates that several properties upstream of Highway 29 would be flooded in the event of dam failure.
Mitigation H&H-NP2: To minimize the potential for dam failure, the City shall have Upper St. Helena Dam evaluated for stability and shall implement recommended seismic stabilization measures (Geology Mitigation GEO-NP4).
Significance after Mitigation. Less than significant.
3.8.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description The Small Notch Alternative is designed to restore the ecological connectivity between habitats upstream and downstream of the dam and allow natural sediment transport while providing a high level of stability for Spring Mountain Road. This alternative calls for the removal of 95% of the accumulated sediment behind the dam and 72% of the actual dam material. A 23-foot wide natural stream channel with a series of pools and riffles would be established through the project site, with 2.0 acres of aquatic and riparian habitat restored (Corps 2006a Appendix A, Corps 2006b). The proposed channel is sized to reflect natural channel morphology and have the capacity to pass the 100-year storm. The existing spillway adjacent to Spring Mountain Road would be filled with sediment from the project site. This provides the most geotechnically stable alternative. Spring Mountain Road traverses a large landslide at the dam site, and maintaining slope stability is a primary concern.
Notching the dam would generate approximately 40,000 cubic yards of materials in total from the reservoir and dam (Corps 2006a). Coarse sediment from the reservoir will be sorted and used for ecosystem restoration at the project site. The remaining material will be reused or disposed of at Lower York Creek Reservoir, Spring Mountain Vineyard, and/or Clover Flat landfill. Materials deposited at Lower York Creek Reservoir would reduce the storage capacity of the reservoir by 10-20%. Water from LYCR is untreated and used for agricultural and construction purposes. The proposed reductions will not significantly impact these uses. Adverse and/or significant hydrologic impacts from the disposal of materials at Spring Mountain Vineyard and Clover Flat landfill are not anticipated, and, therefore, they are not addressed in this section.
The hydrologic effect of UYCD is negligible during storm flows. It reduces peak flows downstream by merely 0.5-2.0% (PCI 2007a). Thus, restoring hydrologic connectivity at the project site will not increase flood hazards or the risk to life or property.
Under this alternative, the annual sediment yield of 1,000 to 1,500 cubic yards of bedload and suspended load that have accumulated in the reservoir would be transported to the lower reaches of York Creek and the Napa River. Downstream of UYCD, the channel is steep (~5% slope), and the bed is composed of coarse gravel, cobble, and scattered boulders. Bedrock outcrops occur within the channel both upstream and downstream of the dam. The channel is
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moderately entrenched, riffle dominated, and appears to be stable in the upper reaches, with few bank erosion sites (NCRCD 2005). Channel slope decreases to 2% where the stream exits the foothills and becomes 1% through the City of St. Helena downstream of Highway 29 (PCI 2007). Downstream of UYCD, the channel has adapted to a sediment starved regime over the last 100 years. It is likely that the channel will undergo physical changes as the system adjusts to renewed sediment inputs. Potential changes include areas of short-term and long-term aggradation, shifts in pool locations and depths, and fining of the bed deposits downstream of the dam.
Hydraulic modeling (HEC-RAS) indicates that notching the dam and restoring a natural channel at a 5% slope through the project site will result in channel velocities that are capable of transporting the annual sediment load in a near equilibrium condition (Corps 2006a). In lower York Creek, through the City of St. Helena, decreasing channel slopes (1-2%) and associated lower velocities reduce sediment transport potential. Analysis of sediment deposits in the reservoir area and in representative reaches throughout the system indicates that the mean grain size carried as bedload ranges from coarse gravel to small cobble. A hydraulic model of the lower reaches suggests that a portion of the delivered material in this size range and larger may be deposited during high frequency storm events downstream of Highway 29 (PCI 2007a). Large cobble size material delivered to this lower reach is likely to accumulate in the channel. Infrequent storm events (>4% exceedance probability) appear to have sufficient stream power to mobilize the coarse material (PCI 2007a). The last 1,000 feet of channel are likely to experience sedimentation during high flow events as a result of backwater conditions from the Napa River.
Impact H&H-PA1: Sediment aggradation in lower York Creek may increase the frequency and severity of flooding. (Potentially significant)
Coarse bedload material that has annually been trapped in the Upper York Creek Reservoir would be delivered to the lower reaches of York Creek. Low channel slopes and areas of poor channel competence create hydraulic conditions conducive to sediment deposition. A preliminary assessment of sediment transport in this reach indicates that gravel and cobble may aggrade the bed downstream of Highway 29 (PCI 2007a). Large, infrequent floods may mobilize and rework sediment deposits. Two areas in lower York Creek are particularly vulnerable to sediment accumulation. The channelized reach from the railroad bridge to the Napa River confluence is likely to experience sedimentation and flooding during periods of high flow on the Napa River when a backwater condition produces low velocities and sluggish stream flow. The reach adjacent to Beringer Winery’s production facilities is currently aggraded and floods bi-annually. Long-term, persistent aggradation of the bed in these reaches may further reduce channel capacities and lead to localized, increased frequency and severity of flooding.
Mitigation H&H-PA1: To minimize the potential impacts of long-term sedimentation on flood capacity in lower York Creek, a channel monitoring program by the City of St. Helena shall be implemented that: • Documents changes in channel cross section area on a regular, pre-determined schedule. • Tracks sediment accumulation at bridges and other critical locations. • Provides guidance on acceptable levels of aggradation.
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• Establishes a mitigation plan should channel aggradation reach a point that it significantly impacts channel capacity and flooding, including: o Defining and prioritizing options for sediment management (i.e., sediment retention basins or in-stream sediment removal). o Obtaining permits required for sediment management practices.
Existing flood hazards will be resolved and future flooding minimized in areas of known low channel capacity and/or sediment accumulation (Beringer Winery reach, channelized reach) by the City of St. Helena through execution of a causative factors analysis and an implementation program to improve channel capacity and promote sediment transport.
Circumstances may occur in which sediment management practices are unable to be implemented in a timely manner (i.e. during winter flows) and temporary, localized changes in existing flood heights and locations may occur. It is not feasible to quantify the likelihood and severity of this potential impact.
Significance after Mitigation: Potentially significant and unavoidable.
Impact H&H-PA2: Construction activities may lead to streambank erosion within the project site. (Potentially significant and long-term)
Reservoir sediment and dam material removal will expose 2,000 linear feet of streambank during construction. If left unprotected by rock and/or vegetation, subsequent stream flows would likely cause bank erosion and long-term slope instability throughout the reach.
Mitigation H&H-PA2: Mitigation measures to avoid post-project streambank erosion within the project site are provided in the Civil Design Appendix (B) of the Final Draft Project Report (Corps 2006a). These measures include soil anchors, rock bank protection to the 100-year flow elevation, and extensive riparian revegetation. Additional mitigation measures to minimize streambank and channel erosion during construction are outlined in Section 3.3, Biological Resources (Mitigation BIO-NP4).
Significance after Mitigation: Less than significant.
3.8.5 Full Dam Removal: Impacts and Mitigation Measures Description The Full Dam Removal Alternative is designed to restore the ecological connectivity of York Creek upstream and downstream of the dam and provide for a natural sediment transport system. This alternative calls for the removal of 100% of sediment accumulated in the reservoir and removal of nearly 100% of the actual dam material. As in the Preferred Alternative, a 23- foot wide natural stream channel with a series of pools and riffles would be established. In addition, a 30-foot wide floodplain bench would be constructed through the project site, and 2.2 acres of aquatic and riparian habitat would be restored (Corps 2006a Appendix A).
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Full removal of the dam entails removing the right wall of the spillway (looking downstream) and stabilizing the hillsides and Spring Mountain Road. It would generate approximately 45,000 cubic yards of materials (Corps 2006a). Coarse sediment from the reservoir will be sorted and used for ecosystem restoration at the project site. The remaining material will be reused or disposed of at Lower York Creek Reservoir, Spring Mountain Vineyard, and/or Clover Flat landfill. Materials deposited at Lower York Creek Reservoir would reduce the storage capacity of the reservoir by 10-20%. Water from LYCR is untreated and used for agricultural and construction purposes. The proposed reductions will not significantly impact these uses. Adverse and/or significant hydrologic impacts from the disposal of materials at Spring Mountain Vineyard and Clover Flat landfill are not anticipated, and, therefore, they are not addressed in this section.
Implementation of the Full Dam Removal Alternative will have similar hydrologic and hydraulic effects on York Creek in the project site and downstream reaches as described under the Preferred Alternative. Potential impacts and mitigation measures associated with increased flooding and streambank erosion in the project site are the same as under the Preferred Alternative (Impacts/Mitigations H&H-PA1, H&H-PA2).
3.8.6 Fish Ladder: Impacts and Mitigation Measures Description The Fish Ladder Alternative is designed to limit the amount of material removed during project construction while still providing for fish passage, sediment transport, and limited ecological connectivity. A portion of the dam would be lowered by 20 feet and a concrete step-pool/weir fish ladder constructed into the remaining dam face. The fish ladder structure would be 23 feet wide to match the natural channel dimensions upstream and downstream. A series of 4-foot wide, 5-foot long, and 20-inch deep box steps would be set into the ladder for fish passage (Corps 2006a Appendix A). These boxes are likely to capture a portion of the annual coarse sediment load and would require on-going maintenance to prevent the ladder from becoming completely clogged with sediment and other debris. A natural channel with the same dimensions and morphology described in the Preferred and Full Dam Removal Alternatives will be constructed upstream and downstream of the fish ladder. The channel upstream of the ladder would have a 3% slope through the reservoir area instead of the 5% in the fully restored channel alternatives. The fish ladder itself would have a 23% slope.
Construction of the fish ladder calls for the removal of 37% of sediment in the reservoir and removal of 52% of the actual dam structure, generating approximately 19,000 cubic yards of material. Materials deposited at Lower York Creek Reservoir would reduce the storage capacity of the reservoir by <10%. Water from LYCR is untreated and used for agricultural and construction purposes. The proposed reductions will not significantly impact these uses. Adverse and/or significant hydrologic impacts from the disposal of materials at Spring Mountain Vineyard and Clover Flat landfill are not anticipated, and, therefore, they are not addressed in this section.
Implementation of the Fish Ladder Alternative will have similar hydrologic and hydraulic effects on York Creek in the project site and downstream reaches as described under the Preferred Alternative. Sediment transport processes may be affected by the presence of a fish ladder, and total annual transport through the project site may be less than under the dam notch and removal alternatives. Potential impacts and mitigation measures associated with
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increased flooding in lower York Creek and streambank erosion in the project site are the same as under the Preferred Alternative (Impacts/Mitigations H&H-PA1, H&H-PA2).
3.8.7 Section References DWR. 2002a. York Creek Dam Removal – Hydraulic Analysis. Division of Planning and Local Assistance, Resource Restoration and Support Branch, Fish Passage Improvement Program. July 2002.
DWR. 2002b. York Creek Sediment Transport Analysis. Division of Planning and Local Assistance, Resource Restoration and Support Branch, Fish Passage Improvement Program. April 2002.
Napa County Resource Conservation District (NCRCD). 2005. Central Napa River Watershed Project, Salmonid Habitat Form and Function. Prepared for California Department of Fish and Game. October 2005.
Parrett, Charles and Richard A. Hunrichs. 2006. Storms and Flooding in California in December 2005 and January 2006—A Preliminary Assessment. U.S. Geological Survey. Open File Report Series 2006-1182.
Prunuske Chatham, Inc. (PCI). 2007a. Hydrology and Hydraulics of Lower York Creek, Napa County, California. March 2007.
U.S. Army Corps of Engineers (Corps). 2005. Upper York Creek Dam Removal Project Section 206: Aquatic Ecosystem Restoration Basin Hydrology Assessment. U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. March 2005.
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California. U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
U.S. Army Corps of Engineers (Corps). 2006b. Draft Environmental Assessment: Upper York Creek Ecosystem Restoration Project, Napa County, California. U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006.
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3.9 Noise 3.9.1 Setting Noise can be generally described as unwanted sound (NCDCDP 2007). Sound travels in waves through the atmosphere in all directions away from the source. Sounds weaken as they travel away from the source and as they travel through obstacles such as trees or walls.
Sound is measured in decibels (dB) and is further standardized using the A-weighted scale (dBA). The human ear is less sensitive to very low and high range frequencies, and the dBA scale, which is commonly used in health and environmental sound calculations, adjusts for this when measuring the sound pressure levels. Sound measurements are logarithmic, so an increase in 10 dB is perceived as double the loudness (UNSW 2006).
Upper Spring Mountain Road adjacent to the project sites contains a number of wineries and residences tucked behind the trees along the heavily wooded road. Background noise is mostly from road traffic, although during various times of the year there is increased noise from winery operations and tourism. Noise from project-related traffic will increase along Spring Mountain Road, but project activities will not result in enough vehicles to significantly increase noise from current traffic levels (Section 3.10, Transportation and Traffic). The Upper St. Helena Dam and Reservoir are not adjoined by any residences, parks, or facilities for sensitive receptors such as hotels, schools, nursing homes, homes for the elderly, or churches. Adverse noise impacts from activities at the upper site are not anticipated.
There are several homes in the vicinity of the Lower York Creek Reservoir. Noise levels will be increased from the delivery and placement of excavated materials on site, although it is anticipated that tree cover and the remoteness of the site will likely buffer noise impacts to neighboring properties. There will be no other impacts from project-related noise to residential neighbors at the lower site.
Spring Mountain Vineyard is a commercial site located away from residences. Clover Flat is the disposal site for unused sediment and waste generated from construction activity. Noise impacts at Clover Flat should not exceed normal levels.
3.9.2 Standards The proposed project would occur in a rural area that generally has lower noise levels than in nearby urban areas. The Napa County Draft General Plan lists the 2006 day-night average sound level (Ldn) along Spring Mountain Road at 68 dBA (NCDCDP 2007). Everyday speech is approximately 60 dBA; an alarm clock is between 65-80 dBA. The Draft General Plan also lists ambient noise levels for 2-lane highways typically carrying traffic at speeds of 45-55 mph at 60 dBA (NCDCDP 2007).
Within the City of St. Helena, an increase of 5 dBA or greater from the average noise environment is considered subjectively significant (Napa County General Plan 1983). The Napa County Baseline Data Report provides recommendations for noise level limits for interior construction activities. Table 6-7 in the report lists the noise limit for residential areas as 75 dBA during the hours of 7 a.m. to 7 p.m. and as 80 dBA for commercial areas (Jones & Stokes and EDAW, Inc. 2005).
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Analysis of increases in noise levels in sensitive receptor areas such as schools, hospitals, nursing homes, facilities for the elderly, and churches is particularly important. Truck traffic would be the only increase in noise levels around sensitive receptors. Traffic levels would not exceed 10% of existing traffic on the various roads assessed as part of this EIR, and, therefore, would not contribute to a significant increase in noise.
3.9.3 No Project Alternative: Impacts and Mitigation Measures Description The No Project Alternative would result in no immediate changes to the current noise levels at Upper St. Helena Dam and Reservoir. On-going maintenance and sediment removal would be required to protect public resources and the safety of downstream residents. An increase in noise levels would be generated from maintenance activities, which would occur during the low water season, likely late summer and/or early fall.
There would be an increase in construction noise at the off-site disposition and disposal locations. Most of the equipment used for the various alternatives, including maintenance under the No Project Alternative, would generate levels around 80-85 dBA. These impacts from the maintenance of Upper St. Helena Dam are considered potentially significant and unavoidable. Maintenance activities are an on-going necessity
Impact NOI – NP1: Truck traffic from maintenance or construction activities could temporarily increase noise levels on Spring Mountain Road. (Less than significant) Upper St Helena Dam and Reservoir, Spring Mountain Vineyard, and the lower reservoir are all located off Spring Mountain Road. Clover Flat is 8.5 miles away on Silverado Trail. Maintenance would result in increased truck traffic along Spring Mountain Road. However, minor increases in noise would only occur in an unpopulated area along the road. A review of the existing conditions and potential project-related traffic impacts has determined that the various alternatives would not create a significant impact (Section 3.10, Transportation and Traffic), and, therefore, impacts from noise would be less than significant.
Mitigation NOI – NP1: No mitigation is required as the impact is less than significant.
Impact NOI – NP2: Maintenance or construction activities would temporarily increase noise at the dam and disposal sites. (Potentially significant, short-term, and unavoidable)
Project activities will result in temporarily increased noise levels at the Upper St. Helena Dam, Spring Mountain Vineyard, Lower York Creek Reservoir, Clover Flat, and along public roads between the various sites. Maintenance and construction will occur during several months during the summer or early fall for three years. Noise at the upper dam would involve heavy equipment including earthmoving and material sorting for transport off site. Table 6-12 in the Napa County Baseline Data Report lists noise levels for various types of construction equipment. Exact equipment will not be known until a contractor is hired. Equipment that would be used for the various alternatives would generate levels around 80-85 dBA.
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Restoration of the stream channel and revegetation improve habitat for wildlife, provide natural creek sounds, and improve buffering of noise.
Mitigation NOI – NP2: The project will occur in a steep canyon, and heavy vegetation should provide natural dampening of the noise levels. Maintenance or construction will occur during daylight hours, and efforts will be made to efficiently schedule construction activities to limit impacts to neighbors at the Lower York Creek Reservoir. Construction activity will be temporary, and the long-term benefit to York Creek and its residents will outweigh short-term impacts from construction. The noise generated from construction activity at the project sites is considered potentially significant and unavoidable.
3.9.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description Noise impacts and mitigation measures from the Small Notch Alternative would be the same as those described for the No Project Alternative. These include short-term increases in noise on Spring Mountain Road and at the dam and disposal sites during project activities (NOI-NP1 and NOI-NP2). Revegetation would result in increased buffering of noise in the long term.
3.9.5 Full Dam Removal: Impacts and Mitigation Measures Description Noise impacts and mitigation measures from the Full Dam Removal Alternative would be the same as those described for the No Project Alternative. These include short-term increases in noise on Spring Mountain Road and at the dam and disposal sites during project activities (NOI-NP1 and NOI-NP2). Revegetation would result in increased buffering of noise in the long term.
3.9.6 Fish Ladder: Impacts and Mitigation Measures Description The fish ladder and the reservoir would require maintenance to keep sediment at levels to allow for fish passage. Noise from maintenance would be similar to the No Project Alternative above, but it would also include removal of sediment and debris from the ladder itself. Sediment removal from the fish ladder would likely be done by hand, although equipment might assist with transporting the material away from the site. Noise impacts and mitigation measures from the Fish Ladder Alternative would be the same as those described for the No Project Alternative. These include short-term increases in noise on Spring Mountain Road and at the dam and disposal sites during project activities (NOI-NP1 and NOI-NP2).
3.9.7 Section References Jones & Stokes and EDAW, Inc. 2005. Napa County Baseline Data Report, Version 1 – November 30, 2005. Prepared for the Napa County Conservation, Development and Planning Department. November 2005. Available for viewing on the Napa County website. Accessed at: http://www.co.napa.ca.us/gov/departments/29000/bdr/index.html
Napa County Department of Conservation, Development and Planning (NCDCDP). 2007. Napa County General Plan Update, Draft for Public Review. February 16, 2007.
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http://www.napacountygeneralplan.com/library/pdgpu.htm
Napa County General Plan 1983, amended 1992. Available for viewing on the Napa County website. Accessed at: http://www.co.napa.ca.us/GOV/Departments/DeptPage.asp?DID=29000&LID=959
University of New South Wales (UNSW). 2006. Music Acoustics website. Accessed at: http://www.phys.unsw.edu.au/jw/dB.html#absolute
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3.10 Transportation and Traffic 3.10.1 Setting Access to the Upper St. Helena Dam and Reservoir, the Lower York Creek Reservoir, and Spring Mountain Vineyard all occur on a short segment of Spring Mountain Road, which is a 2- lane, rural, curvy, mountainous road maintained by Napa County. It runs adjacent to York Creek for nearly 2.5 miles and crosses the creek at three bridges (Corps 2006a). There are approximately two dozen wineries along the road but little other development. The road carries through car and bicycle traffic between St. Helena and Santa Rosa and tourist traffic to the wineries. At the lower end, Spring Mountain Road becomes a city street in St. Helena.
Clover Flat landfill is at 4380 Silverado Trail, 8.5 miles from St. Helena. Truck traffic from the project area to Clover Flat would drive down Spring Mountain Road to city streets. To avoid delays in the left turn onto Main Street, trucks would proceed all the way on Spring Mountain Road to Madrona Avenue, then left on Main Street/SR 29. The intersection of Madrona and Main is signalized. On the return trip, trucks would turn right on Elmhurst, then right on Spring Mountain Road, avoiding most of downtown St. Helena. From St. Helena, trucks would proceed along SR 29 to Deer Park Road and Silverado Trail.
In assessing traffic impacts, current and potential future conditions are described by the level of service (LOS), which represents the speed and travel time, traffic interruptions, predictability of flow, and freedom to maneuver for a particular road. Standards for LOS are based on the kind of street or intersection (Table 17 below). LOS A represents virtually free-flow conditions, with unrestricted ability to maneuver in the traffic stream. Levels B, C, D, E, and F represent decreasing flow rates with correspondingly more interference from other vehicles in the traffic stream. The City of St. Helena General Plan (1993) implements an altered scheme for dividing levels of service into Under Capacity, At Capacity, and Over Capacity.
Table 17. Level of Service (LOS) Classifications Level of Service Classifications (defined by miles per hour) LOS 2-lane Class I Class II Class III Technical Description highway (50 mph) (40 mph) (35 mph) A >55 >42 >35 >25 Free traffic flow. Insignificant delays. Stable traffic flow. Speed and B 50-55 34-42 28-35 19-25 maneuverability slightly restricted. Minimal delays Stable traffic flow but somewhat more C 45-50 27-34 22-28 13-19 restricted. Acceptable delays. Less stable traffic flow. Speeds subject D 40-45 21-27 17-22 9-13 to sudden change. Tolerable Delays Unstable flow. Sudden speed changes E <40 16-21 13-17 7-9 and low maneuverability. Significant delays. F <16 <13 <7 Heavily congested. Excessive delays. Table information based on Caltrans Guide for the Preparation of Traffic Impact Studies and City of St Helena 1993 General Plan.
Spring Mountain Road operates under capacity at LOS A or B. SR 29 sometimes operates at LOS E or F during peak hours, indicating over capacity conditions, in the segment north of Bale Avenue. The segment of SR 29 to be used for trucking operates between LOS A-D (Jones &
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Stokes and EDAW, Inc. 2005). Main Street/SR 29 through St. Helena often operated at LOS A-C in 1990, but it is projected to operate at level D-E by 2030 (NCTPA 2006). Currently, it operates over capacity during peak hours.
Regulatory Setting Spring Mountain Road is a local road in unincorporated Napa County. It is under the jurisdiction of the county of Napa, and an encroachment permit will be obtained for this project.
According to Caltrans criteria, formal traffic information studies should be undertaken if the project:
1) Generates over 100 peak hour trips to a state highway. 2) Generates 50-100 peak hour trips, and the state highway is already at LOS C or D. 3) Generates 1 to 49 peak hour trips, and the road is at LOS E or F (Caltrans 2002).
The project, as mitigated, will generate no peak hour traffic to state highways or to roads with reduced service levels, will generate less than 100 trips per day to Spring Mountain Road, and will involve only temporary traffic effects. Preliminary traffic studies do not indicate any unmitigated significant impacts. Therefore, a formal traffic study was not undertaken.
The project will not conflict with adopted policies, plans, or programs supporting alternative transportation.
3.10.2 Standards Traffic impacts would be considered significant if they exceed 10% of the existing traffic on the road or decrease an existing level of service (Caltrans 2002).
3.10.3 No Project Alternative: Impacts and Mitigation Measures Description The No Project Alternative will have no long-term impacts to traffic. All impacts will be temporary and short-term. The only delay to traffic would be from trucks entering and leaving Spring Mountain Road during routine sediment maintenance operations. It is not known at this time how frequently the City will carry out maintenance activities, and, consequently, it is not known how much sediment will be removed on each occasion. However, some maintenance activities will have to be conducted under the No Project Alternative, and these will necessarily include truck access to Spring Mountain Road from the upper reservoir.
Impact TRA-NP1: Trucks entering and leaving Spring Mountain Road may cause traffic delays. (Potentially significant and short-term)
Since Spring Mountain Road has LOS A or B, any substantial delays could reduce the LOS. Trucks attempting to entering and exiting the project sites could cause such delays.
Mitigation TRA-NP1: In order to minimize delays, the contractor shall:
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• Prepare a traffic control plan using standard Caltrans protocols. The plan will incorporate one or more flaggers for trucks entering and leaving the project sites. Based on experience from maintenance operations during the late summer and early fall of 2006, each delay will be about one minute. • Flaggers shall give emergency vehicles priority so that even when traffic is stopped, emergency vehicles will not be detained.
The traffic control will cause a minor inconvenience to motorists but would be temporary and periodic in nature.
Significance after Mitigation: Less than significant.
3.10.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description This project will have no long-term impacts to traffic. All impacts will be from temporary, short- term construction activities. During construction, there will be additional truck traffic bringing boulders and other construction materials to Upper York Creek Dam and Reservoir and taking away sediments and dam materials for reuse and disposal. Project impacts may result from two sources: construction site access at the upper reservoir and an increase in total traffic caused by trucks moving spoils to reuse and disposal sites. Both will be affected by the project alternative selected because that will determine the amount of material to be relocated and the duration of construction.
A total of approximately 19,000 to 45,000 cubic yards of materials will need to be relocated from the upper reservoir site, depending on the alternative selected. The majority will be placed at Spring Mountain Vineyard and the lower reservoir. About 60% of the total truck traffic generated during construction will stay on a short stretch of Spring Mountain Road. The other 40% will move through St. Helena. Site constraints will limit the number of trucks that can be used to 4 per hour, for a total of 8 trips (4 in and 4 out) per hour, or 48 trips a day. Each truck can carry 12.5 cubic yards of material and still maintain a safe weight for Spring Mountain Road. This will result in 32 to 65 days of truck trips depending on the alternative selected. The Preferred Alternative will generate 40,000 cubic yards of material to be moved off site, resulting in about 56 days of trucking.
These trips can impact traffic in two ways. First, the trips can contribute to the traffic load utilizing a roadway. The relationship of project traffic to total routine traffic in the area is shown in Table 18.
Table 18. Existing Traffic on Hauling Routes and Expected Project Impacts Annual Average Daily % of total traffic generated by Traffic (AADT)* project construction Spring Mountain Road 1,500 3.2 Silverado Trail 4,310 1.1 Main Street 11,000 0.4 Deer Park 3,115 1.5 * Data from Caltrans, “Structure Maintenance & Investigations,” January 2006
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Load traffic can also be evaluated within a specific piece of the day when local or construction traffic is heaviest. The project will generate traffic only during the daytime, so project impact assessment included specific traffic counts on Spring Mountain Road during the daytime. Counts were performed on three different days at times between 8:30 a.m. and 5:30 p.m. during grape harvest season. There are 113 average hourly trips on Spring Mountain Road during daytime hours. The project will generate eight trips per hour during hauling hours, or 7.1% of the traffic on Spring Mountain Road during the day. Since there is no project traffic at night, the project will have no effect on nighttime traffic loads.
Second, the project may add traffic to the already-congested roads in and through the City of St. Helena. Adding traffic to roads that exceed an acceptable level of service is a significant impact under Caltrans traffic evaluation guidelines. Traffic in the city exceeds acceptable levels of service on some roads at peak hours.
Under the Preferred Alternative, the impact on traffic of trucks entering and leaving Spring Mountain Road would be similar to those discussed in the No Project Alternative (TRA-NP1). Other potential impacts from and mitigations for the action alternatives are discussed below.
Impact TRA-PA1: Trucks moving materials from the reservoir to reuse or disposal sites will contribute to traffic loads on the roads. (Less than significant and short-term)
The number of project-related trucks on any road is less than 10% of existing traffic and should not reduce the existing LOS.
Mitigation TRA-PA1: No mitigation is required as the impact is less than significant.
Impact TRA-PA2: The project could generate peak hour traffic to roads that exceed acceptable LOS. (Potentially significant and short-term)
Existing road segments with unacceptable LOS are:
• SR 29 during peak hours in the segment north of Bale Avenue. • Main Street/SR 29 through St. Helena during peak hours.
Trucks will turn off SR 29 before reaching Bale Avenue. However, the project could impact Main Street/SR 29 that is currently operating at LOS E-F during peak hours. In off-peak hours this stretch of road operates within capacity, and the addition of project trucks should not change the LOS. However, at peak hours, from 7 to 9 a.m. and from 3 to 6 p.m., project trucks could make an already bad situation worse. Caltrans considers any addition of traffic on a road operating at LOS E-F to be a potentially significant impact.
Mitigation TRA-PA2: In order to avoid traffic impacts during peak hours, truck traffic on SR 29 through the City of St. Helena will be limited to 9 a.m. to 3 p.m. daily. Trucks may continue to move dam and
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sediment materials to the lower reservoir and Spring Mountain Vineyard outside of these hours.
Significance after Mitigation: Less than significant.
3.10.5 Full Dam Removal: Impacts and Mitigation Measures Description The Full Dam Removal Alternative is the same as the Preferred Alternative except that 45,000 cubic yards of material will be removed over 65 trucking days. Traffic impacts and mitigation measures from the Full Dam Removal Alternative would be the same as those described in the No Project and Preferred Alternatives. These include traffic delays along Spring Mountain Road, increases in traffic loads from trucks moving from the reservoir to disposal sites, and increases in peak hour traffic (TRA-NP1, TRA-PA1, and TRA-PA2).
3.10.6 Fish Ladder: Impacts and Mitigation Measures Description The Fish Ladder Alternative is the same as the Preferred Alternative, except that approximately 19,000 cubic yards of material will be removed over 32 trucking days. Since this material can all be accommodated at the lower reservoir and Spring Mountain Vineyard, no trucks will need to go through the City of St. Helena. Traffic impacts and mitigation measures from the Fish Ladder Alternative would be the same as those described Impacts TRA-NP1 and TRA-P1. These include traffic delays along Spring Mountain Road and increases in traffic loads from trucks moving from the reservoir to disposal sites.
3.10.7 Section References Caltrans. 2002. Guide for the Preparation of Traffic Impact Studies. State of California, Department of Transportation. December 2002.
Caltrans. 2006. Structure Maintenance & Investigations. Localbrlist.rdf. January 2006.
City of St. Helena. 1983. General Plan. September 1983.
Jones & Stokes and EDAW, Inc. 2005. Napa County Baseline Data Report, Version 1 – November 30, 2005. Prepared for the Napa County Conservation, Development and Planning Department. November 2005. Available for viewing on the Napa County website. Accessed at: http://www.co.napa.ca.us/gov/departments/29000/bdr/index.html
Napa County Transportation Planning Agency (NCTPA). 2006. Measure H: An Overview. www.nctpa.net/tax/NCTPA_MeasureH%20v2%20web%20version%20show.pdf.
Prunuske Chatham, Inc. (PCI) 2006c. Traffic Counts on Spring Mountain Road and Potential Impacts from Dam Removal. October 2006. Appendix 6.
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California (DPR). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
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3.11 Water Quality
3.11.1 Setting
3.11.1.1 Introduction This section provides background for the potential threats and benefits to water quality from the Upper York Creek Ecosystem Restoration Project. Project sites reviewed in this assessment include Upper St. Helena Dam and Reservoir, Lower York Creek Reservoir, and Spring Mountain Vineyard. Potential impacts to water quality will be assessed, and mitigation measures will be provided to reduce or eliminate significant impacts resulting from the proposed work.
3.11.1.2 Physical Environment York Creek watershed drains an area of approximately 4.4 square miles from the Mayacmas Mountains that divide Napa from Sonoma County down towards the Napa Valley floor and then to the Napa River. York Creek is a second order stream, meaning that it is a headwater stream fed by two tributaries. York Creek originates in redwoods and conifers at an elevation of about 2,200 feet and travels 7.24 miles, losing nearly 2,000 feet by the time it reaches the Napa River. In the upper reaches, it is largely unaltered except for the presence of the upper dam and reservoir. York Creek is prime habitat for steelhead trout, although the dam effectively blocks approximately two miles of suitable upstream habitat (Corps 2006b). A good combination of pool, riffle, and run stream features occurs both above and below the dam. Through the City of St. Helena, York Creek has been modified by the removal of riparian vegetation, bank modification, levees, and roads (Corps 2006b). The last approximately 0.4 miles are channelized.
Upper St. Helena Dam is 50 feet tall and stretches 140 feet across the channel and banks to concentrate the flow to a drop-inlet snorkel located just behind the face of the dam. The snorkel is a perforated pipe that travels the height of the dam before releasing water on the other side into a small pool. During periods of high flows, a spillway located off the side of the reservoir parallel to Spring Mountain Road takes water approximately 100 feet downstream of the dam directly to York Creek. Steep hillslopes and Spring Mountain Road create a narrow channel for York Creek in this reach along the dam.
3.11.1.3 Water Temperature Water temperature regulates many significant biological and chemical processes in the creek. Temperature is related to levels of dissolved oxygen in the water, as well as the breakdown of chemicals that affect pH. Water temperature is a factor for fish migration and spawning and determines where aquatic organisms live in the creek. Temperature can be influenced by many factors including depth, flow, tributaries, and season.
3.11.1.4 pH pH measures the acidity and alkalinity of water. It is based on a logarithmic scale from zero to 14. Acidic solutions like battery acid or citric acid range from 0-6.9, neutral water has a pH of 7, and alkaline solutions such as bleach and ammonia range from 7.1-14. pH is influenced by chemical processes in the water, such as the breakdown of organic materials, by soils and
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vegetation in the watershed, and by pollution. Most aquatic species require a relatively stable and narrow range of pH to survive.
3.11.1.5 Dissolved Oxygen Dissolved oxygen measures the concentration of oxygen available in the water. Fish and other aquatic species take oxygen from the water and require minimal levels to survive. Dissolved oxygen levels are related to the water temperature. Higher water temperatures mean lower levels of dissolved oxygen. Dissolved oxygen levels are also influenced by the rate of photosynthesis, turbulence in the water, and the chemical processes in the creek.
3.11.1.6 Turbidity Turbidity measures the clarity of the water. Turbidity does not distinguish the cause, such as sediment or other pollutants, just the clarity of the sample. Muddy waters are highly turbid; clear water will result in lower turbidity measurements. Turbid waters can be detrimental to fish and other aquatic life, reducing the ability to feed and reproduce, and often affects other water quality parameters. Turbidity levels, measured in nephelometric turbidity units (NTUs), are affected by natural erosion processes, algae blooms, and human factors such as construction and roads.
3.11.1.7 Asbestos The dam was constructed using on-site materials from the creation of the reservoir (Corps 2006b). Construction materials used to build the dam are believed to include native serpentine soils containing chrysotile asbestos. Asbestos is a group of six different fibrous minerals found in nature (ATSDR 2001). Geologists observed serpentine in outcroppings along Spring Mountain Road and in York Creek (ITSI 2003). Serpentine soils are endemic and unique to the western states. Serpentine is the state rock of California and relatively common in pockets throughout the Bay Area. Asbestos fibers in the serpentine can become airborne and enter the waterway as soil is weathered or disturbed. Airborne asbestos can be carcinogenic if inhaled in sufficient quantities (see Section 3.7, Hazardous Materials, for additional detail). Asbestos fibers do not bind to soils, break down easily, or easily migrate through soils to the groundwater table. It is not believed to accumulate in aquatic life (EPA 2006b).
Soil Borings The Corps retained the services of Innovative Technical Solutions, Inc. (ITSI) to analyze the material in the dam and reservoir. Two soil borings were taken from the dam at multiple depths in September 2003. Materials from the borings were analyzed for a variety of minerals and compounds. ITSI’s test method for asbestos was the California Air Resources Board Method 435 (ITSI 2003). Chrysotile asbestos was found at a maximum concentration of 3.5% in the dam material. Of the two soil borings on the dam, the site closer to Spring Mountain Road had asbestos in both samples. Chrysotile was detected at 3.5% at 15 feet and 2.8% at 35 feet. A composite sample created by combining samples from multiple borings at the same depth in the area from the dam to just behind the snorkel found asbestos at a concentration of 0.25%. This is attributed to the serpentine soils in the area, not any other source. Soil samples collected elsewhere in the reservoir indicated trace to non-detectable levels of asbestos. Dam material will
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be re-used only where it can be capped with clean soil to prevent release into the air from erosion.
Potential Drinking Water Effects The EPA standards for asbestos in drinking water are set at 7 million fibers per liter (MFL) of water. Further research on the effects of asbestos in drinking water found no compelling evidence. Ingested asbestos has not been shown to have carcinogenic effects in populations with high levels of asbestos in their drinking water (WHO 1996). The World Health Organization completed a study to determine whether an asbestos drinking water guideline was needed. The research document led to the conclusion that there is “no consistent, convincing evidence that ingested asbestos is hazardous to health, and it is concluded that there is no need to establish a guideline for asbestos in drinking water” (WHO 1996).
Asbestos in York Creek Water samples were analyzed for asbestos by Caltest at the City’s request. Three sites were tested at two different times for asbestos in the creek upstream of the reservoir, downstream several hundred feet, and in the pool directly below the dam in York Creek.
The first samples were taken after the site had been dewatered for routine sediment removal in September 2006. Some earthwork had begun on site, and the water quality results from the day of the asbestos test show low turbidity results. The water quality notes from the day include a comment about the appearance of new sediment in the pool. The table below shows the test results.
Table 19. Asbestos Test Results from York Creek. 9-27-2006. EPA 100.2 Method # of Asbestos Fibers Concentration of Sample Location in million fibers per Confidence Limits Asbestos Fibers liter (MFL) (MFL) Upstream of Upper 0 0.00-0.73 <0.20 Reservoir
Pool Directly Below 3 6.10-87.00 30.00 Dam*
Downstream of 2 0.10-2.90 0.79 Upper Reservoir* *Due to the presence of many large, non-fibrous particulate matter in the sample, the lab was unable to filter the water to achieve an analytical sensitivity of 0.2 MFL.
Test results showed unusually high levels of asbestos in a pool directly below the dam. The dam contains asbestos, although given knowledge that asbestos does not travel well through soils to groundwater, it seems the likelihood of leaching from the dam is relatively low (EPA 2006b). The asbestos could be slowly leaching from the sediment in the reservoir, although the source of the asbestos in the pool is unknown due to the natural presence of asbestos in the area.
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The tests were redone at the end of January in order to better understand the high asbestos readings in the test results. The first samples could have been somehow tainted or otherwise mishandled. The lab did not make any computation errors in the results. Without any prior baseline data for asbestos in York Creek, we can only speculate about the high results. The retest was delayed due to weather and time constraints. The asbestos test must be submitted to Caltest in Napa, then sent to EMSL in San Leandro (Bay Area) for analysis. The test has a 48- hour hold time, meaning that the sample must be at EMSL within the 48-hour period. Samples were collected at low flows as close to the flows in September as possible given winter conditions. Several rain events have passed through the area since the maintenance project ended with very heavy rains falling during the Christmas to New Year week. The test results are below.
Table 20. Asbestos Test Results from York Creek*. 1-24-07. EPA 100.2 Method Concentration of # of Asbestos Fibers Sample Location Confidence Limits Asbestos Fibers (MFL) (MFL) Upstream of Upper 0 0.00-0.61 <0.17 Reservoir*
Pool Directly Below 0 0.00-0.73 <0.20 Dam
Downstream of 0 0.00-0.61 <0.17 Upper Reservoir* *Due to the presence of many large, non-fibrous particulate matter in the sample, the lab was unable to filter the water to achieve an analytical sensitivity of 0.2 MFL.
The January test results show low levels (below 0.20 MFL) of asbestos in all 3 sites. The samples were collected on a clear day with low turbidity readings. No significant rainfall activity had occurred since the end of December. Maintenance activity wrapped up at the reservoir 2 months prior, and erosion control measures were in place to prepare for winter flows. Maintenance activity removed some sediment, although the reservoir is still far from capacity. The dewatering pipe is no longer carrying water around the site allowing for surface and groundwater flow to the snorkel.
Test results show two very different results for asbestos levels downstream of the upper dam. The nature of asbestos limits its movement through dense material like soil or the dam, although it does not completely block all asbestos from leaching into York Creek. ITSI’s assessment determined that remediation would not be necessary prior to the removal of dam or sediment material. Asbestos in the dam should be relatively stable and should not be contributing to the asbestos in the pool. The sediment in the reservoir closest to the snorkel does contain some asbestos (0.25%) that could be leaching into the pool. The pool itself could contain native serpentine rock resulting in higher levels of asbestos at that location. Low level flows from the perennial (year-round) waters of York Creek could either slowly erode material in the pool or slowly carry material from the reservoir downstream. The low flows would result in high levels of asbestos that would naturally settle in the pool and in the waters downstream. Higher winter flows, especially those as intense as the December 2006 storms, would wash
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away any existing chrysotile asbestos from the site. Based on these findings, the downstream pool will be kept moist, and safety measures listed in Section 3.7, Hazardous Materials, will be followed to prevent asbestos from becoming airborne. Water quality will not be affected by asbestos.
3.11.1.8 Hydrogen Sulfide Hydrogen sulfide is a naturally-occurring, colorless gas present in trapped sediment. The gas smells like rotten eggs and is a byproduct of the bacteria as they break down organic matter in anaerobic or airless conditions like the bottom of the reservoir. It can become a health hazard when released into the air. Hydrogen sulfide can cause symptoms ranging from eye and nose irritation to death (see Section 3.7, Hazardous Materials, for additional details).
Hydrogen sulfide breaks down into elemental sulfur as evidenced by the formation of yellowish soils in the reservoir. Water quality could be compromised if large quantities of gaseous hydrogen sulfide were released quickly downstream. When released into water, hydrogen sulfide becomes hydrosulfuric acid, taking oxygen from the water and creating low dissolved oxygen and pH levels for aquatic life. Dewatering the project area prior to construction and aerating water prior to its release into York Creek would likely remedy the potential to cause harm downstream. Water quality monitoring shall occur at least daily during construction to ensure clean, safe water is delivered downstream.
Table 21. Sulfide Test Results from York Creek. 9-27-2006. EPA 376.2 Method Sample Location Results (mg/L) Upstream of UYC Reservoir ND (non-detectable) Pool Directly Below Dam ND Downstream of UYC Reservoir ND
3.11.2 Standards Water quality standards are determined by federal, state, and local regulators and upheld through various permits. The project will be required to acquire and conform to any monitoring and reporting for environmental permits prior to construction. Water quality standards shall meet the highest level of cleanliness as required by regulators; these may supercede the table below.
This section focuses on the regulatory objectives for water quality as set by the San Francisco Bay Basin Plan. Specific objectives are listed in a table below. Regulatory permits will have project-specific requirements at the time of permit approval, and the more stringent of the requirements will be followed. The San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) has listed the Napa River as an impaired waterbody for excessive sediment, nutrients, and pathogens, so the project would likely require additional monitoring requirements. The SFBRWQCB with the State Water Resources Control Board, sets objectives for acceptable levels of water contamination that still allow for beneficial uses (SFBRWQCB 2006). The project would be considered to have a significant effect if it caused water quality to change so that it no longer meets these objectives as stated in the table below. Criteria are based on measurable quantitative or qualitative standards as stated in the Basin Plan.
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Table 22: Water Quality Objectives from the San Francisco Bay Basin Plan for Surface, Cold Water Habitats
Criteria Objective Bacteria Median less than 240 Most Probably Number (an estimate of bacterial population)/100 ml total coliform bacteria Biostimulatory Substances Substances will not occur at concentrations that promote aquatic growth enough to cause phytoplankton blooms Dissolved Oxygen Minimum of 7.0 mg/L Oil and Grease Levels less than would create a visible film or coating pH Between 6.5 and 8.5, no change greater than 0.5 Sulfide Not above natural background levels Temperature No increase larger than 5º F No toxics in ambient water at concentrations that produce acute Toxicity toxicity Not over 10% if natural background is over 50 nephalometric Turbidity turbidity units (NTU), or at a level that would nuisance or adversely affect beneficial uses. Unionized Ammonia Less than 0.16 mg/L as Nitrate
Based on the standards above, water quality will be monitored for the likely violations. Dissolved oxygen, pH, temperature, and turbidity can be easily measured on site with handheld meters. These would be monitored once sediment is moved at the project site. Other disposition sites would be dry at the time of construction. They will not be monitored for water quality. The only other likely parameter that will be monitored would be sulfides. The City had a water sample sent to the lab to test for sulfides during the most recent maintenance efforts, and they would likely continue to do so if sediments were moved in the reservoir.
3.11.3 No Project Alternative: Impacts and Mitigation Measures Description The dam would remain with no changes to the site. The upper reservoir was constructed with a storage capacity of approximately ten million gallons in an area encompassing 3 acres (Corps 2006a). The reservoir currently stores an estimated 28,000 cubic yards of accumulated sediment. CDFG memos cite four incidents (1965, 1973, 1975, and 1992) of sediment releases into York Creek resulting in fish kills and sedimentation to pools and riffles downstream. Without a project, there is a significant, unavoidable potential for adverse impacts to York Creek and its residents. A catastrophic failure of the dam would result in miles of downstream sedimentation and loss of aquatic life due to highly turbid waters. Impacts could be reduced with routine maintenance of the reservoir to remove accumulated sediment. It is important to note that the 1992 sediment spill occurred during a maintenance effort during low summer flows resulting in up to 18 inches of sediment deposited to downstream pools and riffles and destroying aquatic life for miles to the Napa River.
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Impact WQ – NP1: Water quality in York Creek could be degraded during maintenance activities and result in adverse effects to downstream aquatic life. (Potentially significant and short-term)
Temperature, pH, and dissolved oxygen could be altered from normal background levels during maintenance activities. The project has no components that should affect bacteria, biostimulatory substances, or unionized ammonia. Adverse effects from oil, grease, and/or turbidity could occur from construction equipment working within the bed and bank of York Creek or at the lower reservoir. These impacts will be avoided or minimized by use of BMPs for vehicle maintenance and erosion control in sensitive areas (Section 3.7, Hazardous Materials).
Mitigation WQ – NP1: Monitoring shall occur upstream and downstream of the project site at least daily during all stages of construction with the potential to impact water quality. These requirements may be superseded by ecological permit requirements. The more stringent requirement shall be followed. • A dewatering plan shall be in place prior to any disturbance of sediment to limit water quality impacts (Section 3.3, Biological Resources, for additional details). • Water temperature will not increase more than 5° F. Water temperature is inversely related to dissolved oxygen levels so temperature should be kept as low as possible through the bypass. Increases over 5° F will require changes to the dewatering pipe to allow cool water to move through the project site. Pipe should be kept underground, out of direct sunlight to keep temperatures cool. • pH levels shall be between 6.5 and 8.5, with no change greater than 0.5 to meet Basin Plan objectives. Hydrogen sulfide in the water becomes hydrosulfuric acid, which would lower the pH. pH level changes greater than 0.5 will require careful inspection of the dewatering system to ensure water from the project area does not contaminate water in the pipe. The project area should be completely dewatered prior to sediment disturbance. • The Basin Plan objective for dissolved oxygen requires a minimum level of 7.0 mg/L. Measured levels of dissolved oxygen shall be within 5% of the upstream site and no lower than 7.0 mg/L before leaving the project area. If oxygen levels in the bypass are lower than upstream conditions or 7.0 mg/L, the water shall be agitated to provide oxygenation prior to its release downstream. Agitation could be inherent in the design of the pipe (corrugated pipe would naturally agitate water) or with the installation of an energy dissipator downstream.
Significance after Mitigation: Less than significant.
Impact WQ – NP2: Project activities could result in increased turbidity that adversely affects water quality downstream of the dam to the Napa River. (Potentially significant and short-term)
Maintenance or construction activities shall be completed during the dry months and with the reservoir dewatered to limit the potential for a sediment release downstream. Sediment releases
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from the maintenance of Upper York Creek Dam and Reservoir are considered potentially significant and unavoidable.
Mitigation WQ – NP2: The following mitigation and monitoring measures shall be implemented to prevent adverse impacts to water quality from turbidity: • A Storm Water Pollution Prevention Plan (SWPPP) outlining erosion control and basic construction BMPs shall be prepared and adhered to on the construction site to limit the potential for a sediment release downstream. • A dewatering plan shall be adhered to during maintenance activities (see Section 3.3, Biological Resources, for additional details). • Turbidity will be monitored to meet requirements set forth by the Basin Plan. Turbidity shall not exceed 10% if natural background is over 50 NTU, or at a level that would nuisance or adversely affect beneficial uses. If turbidity levels exceed the 10%, work shall be halted until turbidity is managed onsite. Turbidity shall be measured upstream and downstream of the project site at least daily during all stages of maintenance with the potential to impact turbidity.
Significance after Mitigation: Less than significant.
Impact WQ – NP3: Naturally-occurring asbestos could be released into York Creek from sediment movement during maintenance or construction activities in the reservoir. (Less than significant)
Naturally-occurring asbestos does not pose a water quality threat to York Creek. Efforts will be made to limit releases of sediment that could contain asbestos to York Creek (Mitigation WQ- NP2 above). However, waterborne asbestos from serpentine soils is not regulated by the Regional Water Quality Control Board and, therefore, will not be monitored during maintenance or construction activities.
Mitigation WQ – NP3: No mitigation will be necessary because the impact will be less than significant.
Impact WQ – NP4: Hydrogen sulfide could be released into York Creek from an accidental spill during sediment removal. (Potentially significant and short-term) At low flows, high levels of hydrogen sulfide in the water would be deadly for aquatic life in downstream pools.
Mitigation WQ – NP4: Monitoring shall occur upstream and downstream of the project site at least daily during all stages of maintenance or construction activities with the potential to impact water quality to insure that background levels of hydrogen sulfide are not exceeded. These requirements may be superseded by ecological permit requirements. The more stringent requirement shall be followed.
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• Sulfide levels shall not exceed upstream background levels. If sulfide levels exceed background, work shall be halted until sulfide is managed onsite. The project area should be completely dewatered prior to sediment disturbance. • A dewatering plan shall be in place prior to any disturbance of sediment to limit hydrogen sulfide releases to the water (see Section 3.3, Biological Resources).
Significance after Mitigation: Less than significant.
3.11.4 Preferred Alternative – Small Notch: Impacts and Mitigation Measures Description This alternative will restore fish passage and flow to York Creek. Restoration of the riparian habitat with native plants will stabilize the site and prevent erosion. Water quality conditions should be improved as the stream is returned to a more natural flow and channel.
Materials will be screened and sorted on site at the upper reservoir and then delivered to the various reuse and disposal sites. Water quality concerns at Spring Mountain Vineyard are limited to surface runoff. The placement of materials at Lower York Creek Reservoir will be alongside the edges of the current reservoir and will change its topography. The lower reservoir sediments may or may not be under water depending on the time of year, but the reservoir should be dry at the time of construction. The sediment at the lower reservoir will be protected from erosion with BMPs and a planting plan (see Appendix 2). Clover Flat is a refuse delivery site able to safely store and dispose of fill material.
The Preferred Alternative has the potential to result in impacts due to degraded water quality, increased turbidity, naturally-occurring asbestos, and hydrogen sulfide as discussed in the No Project Alternative. Mitigation measures described in the No Project Alternative will be implemented to reduce impacts to a less than significant level (WQ-NP1, WQ-NP2, WP-NP3, and WQ-NP4).
3.11.5 Full Dam Removal: Impacts and Mitigation Measures Description Implementation of the Full Dam Removal Alternative may have potential impacts due to degraded water quality, increased turbidity, naturally-occurring asbestos, and hydrogen sulfide as discussed in the No Project Alternative. Mitigation measures described in the No Project Alternative will be implemented to reduce impacts to a less than significant level (WQ-NP1, WQ-NP2, WP-NP3, and WQ-NP4).
3.11.6 Fish Ladder: Impacts and Mitigation Measures Description As with the other action alternatives, implementation of the Fish Ladder Alternative may have potential impacts from degraded water quality, increased turbidity, naturally-occurring asbestos, and hydrogen sulfide as discussed in the No Project Alternative. Mitigation measures described in the No Project Alternative will be implemented to reduce impacts to a less than significant level (Mitigations WQ-NP1, WQ-NP2, WP-NP3, and WQ-NP4).
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3.11.7 Section References Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service. Toxicological Profile for Asbestos. 2001.
Caltest Analytical Laboratory. 2006a. Asbestos Results from September 26, 2006.
Caltest Analytical Laboratory. 2006b. Sulfide Results from September 22, 2006.
Caltest Analytical Laboratory. 2007. Asbestos Results from January 24, 2007.
Emig, John. 1992. Memorandum from John Emig, Associate Fisheries Biologist to Warden Jack Edwards. Subject: York Creek Discharge, July 1992. August 4, 1992.
Hunter, Brian. 1992. Letter from Brian Hunter, Regional Manager, to Marty Oldford, Director of Public Works for the City of St. Helena. Subject: Removal of Dam, York Creek. July 30, 1992.
Innovative Technical Solutions, Inc. (ITSI). 2003. Final Report HTW Assessment Upper York Creek Ecosystem Restoration Project St. Helena, California. Prepared for U.S. Army Corps of Engineers San Francisco District. December 2003.
Jones & Stokes and EDAW, Inc. 2005. Napa County Baseline Data Report, Version 1 – November 30, 2005. Prepared for the Napa County Conservation, Development and Planning Department. November 2005. Available for viewing on the Napa County website. Accessed at: http://www.co.napa.ca.us/gov/departments/29000/bdr/index.html
San Francisco Bay Regional Water Quality Control Board (SFBRWQCB). 2006. The Water Quality Control Plan for the San Francisco Bay Basin (Basin Plan). December 22, 2006. Accessed at: http://www.swrcb.ca.gov/rwqcb2/basinplan.htm
U.S. Army Corps of Engineers (Corps). 2006a. Final Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California (DPR). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. December 15, 2006.
U.S. Army Corps of Engineers (Corps). 2006b. Draft Environmental Assessment: Upper York Creek Ecosystem Restoration Project, Napa County, California (EA). U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006.
U.S. Environmental Protection Agency. 2006b. Ground Water and Drinking Water Consumer Factsheet on Asbestos. Accessed at: http://www.epa.gov/ogwdw000/dwh/c-ioc/asbestos.html
World Health Organization (WHO). 1996. Asbestos in Drinking-Water: Background Document for Development of WHO Guidelines for Drinking-Water Quality. Accessed at: http://www.who.int/water_sanitation_health/dwq/asbestos.pdf
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4 Impacts Analysis This chapter analyzes potential environmental impacts of the Upper York Creek Ecosystem Restoration Project, including the No Project Alternative. The purpose of describing and analyzing a No Project Alternative is to allow the public and agency decision-makers to compare the impacts of approving the proposed project with impacts should the project not be approved. Significant and unavoidable impacts, cumulative impacts, irreversible effects, and long-term versus short-term impacts are outlined. Also included is a discussion of the beneficial effects and the environmentally superior project alternative.
4.1 Significant and Unavoidable Impacts Details regarding impacts to specific environmental resources potentially affected by the proposed Upper York Creek Ecosystem Restoration Project, and their associated mitigation measures, are found in Section 3, Environmental Setting and Consequences of Project Alternatives. The list below outlines the potentially significant and significant environmental impacts that could not be eliminated or reduced to less than significant after implementation of feasible mitigation measures. The impacts of the No Project Alternative are distinguished from the proposed action alternatives.
4.1.1 No Project Alternative The following significant and unavoidable impacts have been identified for the No Project Alternative: • Aesthetics Placement of materials removed from the upper reservoir during sediment maintenance activities may result in potentially significant, recurring visual impacts at the lower reservoir. • Biological Resources Upper St. Helena Dam would continue to act as an unnatural upstream and downstream migration barrier to fish and other aquatic species, resulting in a significant and unavoidable impact. Upper York Creek Dam and Reservoir would continue to disrupt the natural transport of materials and organisms, reducing their availability for downstream habitat and food, and significantly adversely affecting aquatic species and habitat.
• Global Climate Change Maintenance activities to remove sediment and debris will increase carbon dioxide by committing the City to repeated projects. • Noise Recurrent maintenance activities may increase noise significantly at the dam and sediment disposal sites.
4.1.2 Action Alternatives The following significant and unavoidable impacts have been identified for the Preferred Small Notch, Full Dam Removal, and Fish Ladder Alternatives:
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• Aesthetics Placement of materials removed from the upper reservoir during project activities may result in potentially significant visual changes at the Lower York Creek Reservoir by reducing the reservoir surface area by 2-6%. • Biological Resources The fish ladder would act as a partial, unnatural upstream and downstream migration barrier to fish and other aquatic species, resulting in a significant and unavoidable impact. [Fish Ladder Alternative only] • Cultural Resources Removal of the Upper St. Helena Dam and associated structures would have a significant adverse impact on the historic feeling, design, and association of a resource considered eligible for listing in the National Register of Historic Places and the California Register of Historical Resources. • Global Climate Change Maintenance activities to remove sediment and debris will increase carbon dioxide by committing the City to repeated projects. [Fish Ladder Alternative only] • Hydrology and Hydraulics Under specific, unmanageable conditions, sediment aggradation during a storm event may temporarily increase the localized severity of flooding within City limits along lower York Creek. • Noise Maintenance and/or construction activities may increase noise significantly at the dam and disposal sites.
4.2 Cumulative Impacts Cumulative impacts may occur if two or more individual effects, when considered together, are considerable or compound or increase other environmental impacts. The cumulative impact from several projects is the change in the environment that results from the incremental impact of the project when added to other closely related past, present, and reasonably foreseeable future projects. Cumulative impacts can result from individually minor but collectively significant projects taking place over a period of time (CCR §15355).
For the purposed of this DEIR, the California CEQAnet database was consulted for projects currently in planning for the greater St. Helena area. Projects were included if they were within the City, on the haul routes, or within a 5-mile radius (for projects affecting sensitive receptors21). These included the following:
1) St. Helena Hospital – Three-phase project over 20 to 25 years including new patient building, power plant, cooling plant, and new parking spaces. 2) City of St. Helena Comprehensive Flood Protection Project – The City of St. Helena is developing a plan that, when implemented, will reduce damage from Napa River
21 Sensitive receptors include schools, hospitals, parks, homes for the elderly, etc.
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flooding in a manner that will result in an overall improvement to the health of the ecosystem in the project reach. 3) City of St. Helena Wastewater Treatment Plant Upgrade – Upgrade and expansion of existing facilities to include a treatment system to produce disinfected tertiary recycled water to meet Regional Water Quality Control Board (RWQCB) discharge requirements and meet the City's 2010 demands for wastewater treatment. 4) David Vineyard Conversion – Conversion of 8 acres on a 54-acre parcel to vineyards. 5) Harold Smith Weir Maintenance – Maintenance to existing vortex weirs on Sulphur Creek to re-establish a single channel and ensure fish passage through the weirs. 6) Culinary Institute – Remodel, addition of 85 parking spaces, and removal and replanting of trees. 7) Grand View Inn – Conversion of a ±40-unit multiple family residential development into a 40-room inn. Fourteen residential units will be retained as affordable housing. The project would include historic restoration. New street access would be established. 8) Schultz Bridge – Installation of a free span bridge over Canon Creek. 9) Trinchero Family Estate Winery Remodel – Remodel and expansion of an existing winery including a two-story, 20,792-square foot building with an adjoining outdoor patio and construction of a new 7,208-square foot hospitality-office building. 10) Youth Center Expansion – Removal of 5 portable structures and replacement with a ±11,300-square foot joint use youth facility. 11) Conelly/Carpy Vineyard Conversion – Development of a new 10-acre vineyard. 12) Turley Wine Cellars Bank Stabilization – Stabilization and vegetation of a loose, erosive right bank of Mill Creek on the Turley property. 13) Magnolia Oaks – Subdivision of a 5.86-acre parcel into 33 lots. A total of 45 housing units will be constructed on 31 of the 33 lots. 14) Bekker Winery Expansion – New 15,000-gallon per year winery totaling 3,348 square feet; conversion of four structures; addition of a crush pad area and outside work area of 2,100 square feet. 15) Aquatic Weed and Algae Control at Milliken Diversion Dam and Lake Hennessy – Proposed use of copper to control algae and other aquatic weeds in Milliken Reservoir and Lake Hennessy.
For some impact areas, such as air quality, global climate change, and water quality, cumulative impacts were assessed on a basin-wide scale and based on regulatory guidelines rather than specific projects.
A cumulative impact analysis was completed for all of the environmental factors described in Section 3. Projects in the vicinity do not contribute to cumulative impacts in the following resource areas: aesthetics, biology, cultural resources, geology, hazardous materials, hydrology and hydraulics, and noise. Impacts to air quality from PM10 emissions are below levels defined as cumulatively significant by the Bay Area Air Quality Management District. Potential cumulative impacts associated with the implementation of the Upper York Creek Ecosystem Restoration Project are restricted to impacts to global climate change and traffic, which are discussed below.
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4.2.1 Global Climate Change Net cumulative contributions to carbon dioxide concentrations were identified for the No Project Alternative. Recurrent maintenance activities at the dam to remove sediment will produce carbon dioxide levels that are not likely to be mitigated through on-site vegetation restoration or construction practices. These ongoing carbon dioxide contributions, in combination with other greenhouse gas producing projects, are likely to cumulatively contribute to global warming. Carbon dioxide contributions in the project’s action alternatives are mitigated by riparian revegetation.
4.2.2 Traffic Under the Preferred Small Notch, Full Dam Removal, and Fish Ladder Alternatives, the project could add traffic to an area that is already exceeding acceptable levels of service, resulting in significant cumulative impacts. This applies to roads in and through the City of St. Helena that are experiencing congestion. These impacts would be short-term, occurring only during project activities.
4.3 Irreversible Impacts Significant irreversible environmental changes are those that would be caused by a proposed project should it be implemented. Such changes include use of non-renewable resources, commitment of future generations to similar uses, and environmental accidents that could occur as a result of the project (CCR 15126.2(c)).
Under all proposed action alternatives for the Upper York Creek Ecosystem Restoration Project, irreversible environmental changes would occur. The dam is a unique historical resource, and alteration would result in irreversible changes to a historic structure and its setting. Restoring sediment transport functions through the project site may result in changes to the lower York Creek and Napa River channels. Coarse sediment may aggrade the streambed in lower York Creek during a storm event, leading to temporary increased flooding potential. The proposed project alternatives would require the use of non-renewable resources in the form of fuel and construction materials.
Under the No Project and Fish Ladder Alternatives, maintenance activities would be required, and resource use would be on-going into the foreseeable future. Protective measures will be in place during project implementation to guard against accidental releases of hazardous materials (i.e., sediment, fuel, etc.). See specific BMPs and mitigation measures in Section 3.
4.4 Growth Inducing Effects Growth-inducing impacts are defined as changes that could foster economic or population growth or construction of additional housing, either directly or indirectly, in the surrounding environment. Included in this are projects that would remove obstacles to population growth (CCR 15126.2(d)).
The proposed project, under all alternatives, would not remove obstacles to growth nor require additional public services. Although it may set precedence for future ecological restoration projects, such actions would not induce growth. Accordingly, the Upper York Creek Ecosystem Restoration Project would have less than significant growth-inducing impacts.
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4.5 Short-term Impacts vs. Long-term Effects Short- and long-term effects on the environment from the project alternatives, including the No Project Alternative, are assessed in this section (CCR §15126.2(a)). The removal or modification of Upper York Creek Dam and Reservoir and restoration of the ecosystem in the project area will result in both losses and gains in the affected environment.
Short-term impacts would result from construction activities under all project alternatives. These would include potentially significant increases in noise at the dam and material disposition sites, increased traffic congestion on Spring Mountain Road and other project transportation routes, destruction of riparian and aquatic habitat, and reduced aesthetic and scenic values. Under the No Project Alternative, sediment maintenance activities would result in these short-term impacts recurring regularly in perpetuity.
Long-term effects of the proposed action alternatives include increasing and improving in- stream habitat for threatened populations of steelhead trout and other aquatic organisms, restoring the site to a more natural state resembling that of pre-dam conditions (not applicable in the Fish Ladder Alternative), and re-establishing sediment delivery to downstream reaches. Coarse sediment delivered to the lower watershed will both improve aquatic habitat conditions and potentially alter channel conveyance during high flows. The removal of the dam would result in a permanent loss of a historic structure. Overall, the long-term environmental gains from the Upper York Creek Ecosystem Restoration Project appear to outweigh the short-term impacts and long-term losses.
4.6 Beneficial Effects and the Environmentally Superior Alternative Determination of the environmentally superior alternative is based on the accomplishment of project objectives, maximizing beneficial environmental effects, and the avoidance or substantial reduction of potentially significant impacts. The three primary project objectives are described fully in Section 1. They include: • Improved fish passage and habitat connectivity. • Reduced future downstream habitat degradation and fish kills from low-flow fine sediment releases. • Habitat restoration within the project area. A detailed impacts analysis is provided above in Sections 4.1 through 4.5. The following discussion includes an overview of beneficial impacts and culminates in the presentation of the environmentally superior project alternative.
A natural creek bed restored to its historic location, slope, and geomorphic components occurs under the Full Removal and Preferred Small Notch Alternatives. The reinstated channel will provide complete habitat connectivity and passage for all life stages of steelhead, as well as movement and dispersal of other aquatic and terrestrial wildlife species. The Fish Ladder Alternative would provide adult steelhead passage over the lowered dam during the rainy season and limited passage for adults and juveniles during other times of the year, provided sufficient flows were present. The high, concrete fish ladder would present a significant, un-
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natural barrier for smaller fish as well as other aquatic and terrestrial species. Under the No Project Alternative, fish passage and habitat connectivity would not be restored.
The Full Dam Removal and Preferred Small Notch Alternatives remove at least 95% of the sediment stored in the reservoir, restore natural sediment transport, and eliminate the threat of an accidental release of accumulated sediment. The Fish Ladder Alternative will leave nearly 65% of the fine-grained reservoir sediment in place while subsequently allowing unrestricted sediment transport through the ladder. Sediment transport potential through the reconstructed reach upstream of the fish ladder may be reduced for coarse sediment, as the channel slope will be constructed at 3% instead of the natural channel’s 5%. Under the No Project Alternative, sediment will continue to accumulate in the reservoir, resulting in an on-going potential for detrimental fine sediment releases from catastrophic dam failure and/or sediment removal activities.
Each of the action alternatives includes reestablishing approximately 2 acres of currently disturbed riparian habitat and 1.5 acres of in-stream habitat. Construction of a complex, natural channel and revegetation of the banks with native trees and plants to create a mature riparian environment and provide bank stabilization are included in each action alternative. Restoration of the creek to most closely reflect local, historic conditions and provide full ecosystem connectivity occurs only in the Full Dam Removal and Preferred Small Notch Alternatives. Sediment removal activities under the No Project Alternative will frequently disturb the 1.5 acres of riparian and in-stream habitat within the reservoir, displacing the aquatic and terrestrial inhabitants.
Spring Mountain Road is sited on a landslide immediately adjacent to the dam and spillway. Currently, the dam functions as a stabilizer for the unstable hill slope. Maintaining the stability of Spring Mountain Road at this location is a mandatory design constraint. Both the Full Dam Removal and Preferred Small Notch Alternatives potentially destabilize the landslide. The Full Dam Removal Alternative requires the highest level of slope reinforcement measures for long- term structural stability. A higher level of slope stability is provided by the Preferred Small Notch Alternative through backfilling the spillway, leaving a portion of the dam fill as a buttress, and reinforcing the slopes adjacent to the channel.
Of the alternatives analyzed, the Preferred Small Notch Alternative is judged to be environmentally superior because it provides for the highest levels of ecosystem restoration and protection, while providing for greater slope stability than the Full Dam Removal Alternative. Beneficial environmental effects of the Preferred Small Notch Alternative include restored access to 1.7 miles of high quality habitat for steelhead trout; restored habitat connectivity and unimpeded migration for aquatic and terrestrial organisms; elimination of the threat of harmful low-flow fine sediment releases; and reestablished natural sediment transport processes to improve in-stream habitat in York Creek and the Napa River. Long-term impacts associated with the Preferred Small Notch Alternative include removal of an eligible historic structure (Upper St. Helena Dam) and a possibility for changes in existing flood heights due to localized, temporary channel aggradation in lower York Creek. Construction activities are likely to produce short-term significant impacts to noise levels, traffic congestion, and aesthetics at the Upper and Lower York Creek Reservoirs.
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5 List of Preparers and Reviewers
City of St. Helena 1480 Main Street St. Helena, CA 94574
Project Manager: Jonathon Goldman, Director of Public Works and City Engineer Reviewers: John Ferons, Associate City Engineer Bert Johansson, City Manager Carol Poole, Planning Director Amy L. Valukevich, City Attorney
5.1 EIR Consultants Prunuske Chatham, Inc. PO Box 828 Occidental, CA 95465
Project Principal: Steven Chatham Project Manager: Jon Mann, Senior Professional Engineer Task Manager Kathie Lowrey, Senior Environmental Planner Assistant Task Manager: Jennifer Michaud, Wildlife Biologist
Staff Contributors: Harold Appleton, Registered Professional Forester Chris Choo, Planning Assistant Aimee Crawford, Environmental Planner II Lauren Hammack, Geomorphologist/Hydrologist John Pawson, Senior CAD Operator Liza Prunuske, Principal Anna Quinn, CAD Operator Laura Saunders, Environmental Planner I
Coast Range Biological, LLC. PO Box 1238 Santa Cruz, CA 95061
Tom Mahoney, Principal/Plant Ecologist
Blackburn Consulting 11521 Blocker Drive, Suite 110 Auburn, CA 95603
W. Eric Nichols, Certified Engineering Geologist
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6 Acronyms and Abbreviations
AADT average annual daily trips ACM asbestos containing material AES Aesthetics AFS American Fisheries Society AIR Air Quality ATSDR Agency for Toxic Substances and Disease Registry ATCM Airborne Toxic Contaminant Measure BAAQMD Bay Area Air Quality Management District BCC Bird of Conservation Concern BGEPA Bald and Golden Eagle Protection Act BIO Biological Resources BLM Bureau of Land Management BMP(s) best management practices CARB California Air Resources Board CalEPA California Environmental Protection Agency CBC California Building Code CCC Central California Coast CCR California Code of Regulations CDF California Department of Forestry CDFG California Department of Fish and Game CSC California Species of Concern CEQA California Environmental Quality Act CFR Code of Federal Regulations CGS California Geologic Survey City City of St. Helena cm centimeter CO carbon monoxide Corps U.S. Army Corps of Engineers CRLF California red-legged frog CNDDB California Native Diversity Database CNPS California Native Plant Society CUL Cultural Resources dB decibels dBA A-weighted decibels DOSH Division of Occupational Safety & Health (State of Calif.) DPR Draft Project Report DWR Department of Water Resources EA Environmental Assessment EDAW Eckbo, Dean, Austin and Williams (company name) EIR Environmental Impact Report EMSL Company name EPA Environmental Protection Agency ESA Endangered Species Act ESU evolutionarily significant unit et seq. and following F Fahrenheit
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FE federally listed as endangered FL Fish Ladder Alternative FPD Proposed for Delisting FR Full Removal Alternative FS USDA Forest Service FT federally listed as threatened FYLF foothill yellow-legged frog g gravity GEO Geology, Soils, Landslides, and Seismic Activity GHG greenhouse gas GIS geographic information system GLO Global Warming and Climate Change H&H Hydrology and Hydraulics HAZ Hazardous Materials HEPA high efficiency particulate air (filter) HEC HMS hydraulic modeling system i.e. that is IPCC International Panel on Climate Change ITSI Innovative Technical Solutions, Inc. kg kilogram
Ldn day-night average sound level lb(s) pound(s) LOS level of service LYCR Lower York Creek Reservoir MBTA Migratory Bird Treaty Act mg milligram mg/L milligrams per liter MFL million fibers per liter ml milliliter mm millimeter MMT million metric tonnes mph miles per hour MPN Most Probable Number (an estimate of bacterial population) NCDCDP Napa County Department of Conservation, Development and Planning NCRCD Napa County Resource Conservation District ND non detectable NEPA National Environmental Policy Act NMFS NOAA Fisheries National Marine Fisheries Service NOA Naturally occurring asbestos NOAA National Oceanic & Atmospheric Administration NOI Noise NOP Notice of Preparation NP No Project Alternative NTU nephelometric turbidity units OEHHA Office of Environmental Health Hazard Assessment OSHA Occupational Health and Safety Administration PA Preferred Alternative, Small Notch
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PCI Prunuske Chatham, Inc. pH potential of hydrogen PM10 particulate matter less than 10 microns PM2.5 particulate matter less than 2.5 microns ppb parts per billion pphm parts per hundred million ppm parts per million PRG Preliminary Remedial Goal RCD Resource Conservation District SFBRWQCB San Francisco Bay Regional Water Quality Control Board SCH California State Clearinghouse SC Species of Concern SE state listed as endangered SMV Spring Mountain Vineyard SR State Route SHPO State Historic Preservation Officer ST state listed as threatened SWPPP Storm Water Pollution Prevention Plan TAC toxic air contaminant TRA Transportation and Traffic µg/m3 microgram per cubic meter UNSW University of New South Wales USDA United States Department of Agriculture USDOE United States Department of Energy USFWS United States Fish and Wildlife Service USGS United States Geological Survey USHDR Upper St. Helena Dam and Reservoir UYCD Upper York Creek Dam WHO World Health Organization WQ Water Quality
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7 References Ackerman, A. and E. Stanton. 2006. Climate Change - The Costs of Inaction. Global Development and Environment Institute, Tufts University. October 11, 2006.
Adams, K. 2007. Thesis presentation on genetic variability in Oncorhynchus mykiss above and below permanent fish passage barriers. Sonoma State University. February 2007.
Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service. Toxicological Profile for Asbestos. 2001. *
Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Public Health Service. Medical Management Guidelines for Sulfur Dioxide. CAS #7446-09-05. UN# 1079. Accessed at: http://www.atsdr.dcd.gov/mhmi/mmg116.html *
Association of Environmental Professionals. 2005. California Environmental Quality Act Statutes and Guidelines. **
Bay Area Air Quality Management District (BAAQMD). 1999a. BAAQMD CEQA Guidelines: Assessing the Air Quality Impacts of Projects and Plans. Prepared by the Planning and Research Division of the Bay Area Air Quality Management District. December 1999. *
Bay Area Air Quality Management District (BAAQMD). 1999b. BAAQMD Rule 9-2 Inorganic Gaseous Pollutants, Hydrogen Sulfide. Amended October 6, 1999.
Bay Area Air Quality Management District (BAAQMD). 2007a. Ambient Air Quality Standards and Bay Area Attainment Status. Accessed at: http://www.baaqmd.gov/pln/air_quality/ambient_air_quality.htm
Bay Area Air Quality Management District (BAAQMD). 2007b. Asbestos Airborne Toxic Control Measure for Construction and Grading Operations. Asbestos Dust Mitigation Plan Application. *
Bay Area Air Quality Management District (BAAQMD). 2007c. Emission Inventory. Accessed at: http://www.baaqmd.gov/pln/emission_inventoryYear2003BY00.htm
Berner, M., B. Grummer, R. Leong, and M. Rippey. 2003. Breeding Birds of Napa County, California. Napa-Solano Audubon Society, Vallejo, California. **
Blackburn Consulting, Inc. 2006. Geotechnical Data Report, Upper York Creek Dam Removal Project, St. Helena, California. January 17, 2006. **
Blake, Thomas F. 2000. EQFAULT: A Computer Program for the Estimation of Peak Horizontal Acceleration from 3-D Fault Sources, Version 3.00. April 2000. **
Bourdes, V., P. Boffetta, and P. Pisani. 2000. Environmental exposure to asbestos and risk of pleural mesothelioma: review and meta-analysis. European Journal of Epidemiology 16:411-417.
* Document is available on the City of St. Helena website at www..ci.st-helena.ca.us/. ** Document is available at public libraries or directly from the source.
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California Air Resources Board (CARB). 2002. Naturally-Occurring Asbestos General Information. California Environmental Protection Agency. Accessed at: http://www.arb.ca.gov/toxics/asbestos/general.htm
California Air Resources Board (CARB). 2005. Ambient Air Quality Standards for Particulate Matter. Accessed at: http://www.arb.ca.gov/research/aaqs/pm/pm.htm
California Climate Change Center (CCEC). 2006. Our Changing Climate: Assessing the Risks to California. Union of Concerned Scientists, Scripps Institute of Oceanography, California Energy Commission, University of California, Berkeley, and California Air Resources Board. CEC-500-2006-077. July 2006.
California Department of Fish and Game (CDFG). 2000. A List of Freshwater, Anadromous, and Euryhaline Fishes of California. California Fish and Game 86(4):244-258.
California Department of Fish and Game (CDFG). 2002. California Climate Based on the Köppen Classification System. GIS coverage. Wildlife and Habitat Data Analysis Branch, Sacramento, California. **
California Department of Fish and Game (CDFG). 2003. List of California Terrestrial Communities Recognized by The Natural Diversity Database. California, September 2003. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2006a. California Natural Diversity Database, RareFind Version 3.1.0. California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2006b. Complete List of Amphibian, Reptile, Bird, and Mammal Species in California, March 2006. California Department of Fish and Game Sacramento, California.
California Department of Fish and Game (CDFG). 2006c. Special Animals, February 2006. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2006d. State and Federally Listed Endangered and Threatened Animal of California, October 2006. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2007a. Special Vascular Plants, Bryophytes, and Lichens List, January 2007. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
California Department of Fish and Game (CDFG). 2007b. State and Federally Listed Endangered, Threatened, and Rare Plants of California, January 2007. California Natural Diversity Database, California Department of Fish and Game, Sacramento, California.
* Document is available on the City of St. Helena website at www..ci.st-helena.ca.us/. ** Document is available at public libraries or directly from the source.
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California Environmental Protection Agency (CalEPA). 2006. A Guide to Health Risk Assessment. Office of Environmental Health Hazard Assessment, California Environmental Protection Agency.
California Geological Survey. 1999. Geologic Map of the Santa Rosa Quadrangle, Map No. 2A, Scale 1:250,000. **
California Geological Survey. 2006. Seismic Shaking Hazards in California. Accessed November 27, 2006 at: http://www.consrv.ca.gov/cgs/rghm/pshamap/pshamain.html
California Invasive Plant Council. 2006. Invasive plant inventory. Accessed at: http://portal.cal- ipc.org/weedlist
California Native Plant Society. 2006. Inventory of Rare and Endangered Plants (online edition, v6-05b). California Native Plant Society. Sacramento, California. Accessed at: http://www.cnps.org/inventory
California Office of Planning and Research. 2006. State Clearinghouse (SCH) CEQAnet Database. Accessed at: http://www.ceqanet.ca.gov/ **
Caltest Analytical Laboratory. 2006a. Asbestos Results from September 26, 2006.
Caltest Analytical Laboratory. 2006b. Sulfide Results from September 22, 2006.
Caltest Analytical Laboratory. 2007. Asbestos Results from January 24, 2007.
Caltrans. 2002. Guide for the Preparation of Traffic Impact Studies. State of California, Department of Transportation. December 2002.
Caltrans. 2006. Structure Maintenance & Investigations. Localbrlist.rdf. January 2006.
City of St. Helena. 1983. General Plan. September 1983. **
Cox, Bill. 2002. Memorandum from Bill Cox, District Fishery Biologist, to Lt. Don Richardson. Subject: York Creek, Napa County. September 27, 2002.
Department of Water Resources (DWR). 2002a. York Creek Dam Removal – Hydraulic Analysis. Division of Planning and Local Assistance, Resource Restoration and Support Branch, Fish Passage Improvement Program. July 2002. *
Department of Water Resources (DWR). 2002b. York Creek Sediment Transport Analysis. Division of Planning and Local Assistance, Resource Restoration and Support Branch, Fish Passage Improvement Program. April 2002. *
* Document is available on the City of St. Helena website at www..ci.st-helena.ca.us/. ** Document is available at public libraries or directly from the source.
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Department of Water Resources (DWR). 2003. Biological Assessment for the York Creek Diversion Modification Project, City of St. Helena. Prepared for the City of St. Helena. May 21, 2003. *
Department of Water Resources (DWR). 2004. Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project. January 14, 2004. *
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Eastman, B. 2003. Historical Resources Evaluation Report for the Proposed Removal of an Earthen Dam and Diversion Structure on York Creek near the City of St. Helena in Napa County, California. Prepared for the City of St. Helena by Bright Eastman, Anthropological Studies Center, Sonoma State University, Rohnert Park, California. *
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High-Volume Fly-Ash Concrete Technology (HVFAC). 2005. Canadian International Development Agency, Natural Resources Canada, and Confederation of Indian Industry cooperative project. Accessed at: http://www.hvfacprojectindia.com/projects/backgrounds.htm
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Jones & Stokes. 2006. Biological Assessment, St. Helena Comprehensive Flood Protection Project. Prepared for the City of St. Helena. Revised July 2006. **
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Napa County Department of Conservation, Development and Planning (NCDCDP). 2007. Napa County General Plan Update, Draft for Public Review. February 16, 2007. Available for viewing on the Napa County website. Accessed at: http://www.napacountygeneralplan.com/library/pdgpu.htm **
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Nelson, James R. 1987. Rare Plant Surveys: Techniques for Impact Assessment. From proceedings of a California Conference on the Conservation and Management of Rare and Endangered Plants. California Native Plant Society. Sacramento, California. **
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Parmesan, C., and G. Yohe. 2003. A globally coherent fingerprint of climate change impacts across natural systems. Nature 421, 37–42.
Parmesan, C. 2006. Ecological and Evolutionary Responses to Recent Climate Change. Annual Review of Ecology, Evolution and Systematics. 37: 637-669.
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Parrett, Charles and Richard A. Hunrichs. 2006. Storms and Flooding in California in December 2005 and January 2006—A Preliminary Assessment. U.S. Geological Survey. Open File Report Series 2006-1182. **
Pew Center on Global Climate Change and Pew Center on the States. 2006. Climate Change 101, the Science and Impacts.
Prunuske Chatham, Inc. (PCI). 2004. Letter from Jennifer Michaud, Wildlife Biologist, to National Marine Fisheries Service. Subject: York Creek Diversion Modification Project, City of St. Helena, Napa County, Summary of Fish Relocation Activities. November 4, 2004.
Prunuske Chatham, Inc. (PCI). 2006a. California Red-legged Frog (Rana aurora draytonii) Site Assessment, York Creek Sediment Removal Project, City of St. Helena, May 2006.
Prunuske Chatham, Inc. (PCI). 2006b. Letter from Jennifer Michaud, Wildlife Biologist, to Greg Martinelli, Department of Fish and Game. Subject: York Creek Sediment Removal Project, Notification Number: 1600-2006-0224-3, Summary of Fish Relocation Activities. October 17, 2006.
Prunuske Chatham, Inc. (PCI) 2006c. Traffic Counts on Spring Mountain Road and Potential Impacts from Dam Removal. October 2006. Appendix 6.
Prunuske Chatham, Inc. (PCI). 2007a. Hydrology and Hydraulics of Lower York Creek, Napa County, California. March 2007. *
Prunuske Chatham, Inc. (PCI) 2007b. Lower York Creek Dam Revegetation and Mitigation Plan. January 2007. Appendix 2.
Prunuske Chatham, Inc. (PCI). 2007c. Northwest Information Center cultural resources search summary. Technical memo. Appendix 5.
Prunuske Chatham, Inc. (PCI). 2007d. Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir, Spring Mountain Road, City of St. Helena, Napa County. Prepared for the City of St. Helena. March 2007. Appendix 4.
Riparian Habitat Joint Venture (RHJV). 2004. The Riparian Bird Conservation Plan: A Strategy for Reversing the Decline of Riparian Associated Birds in California, Version 2.0. California Partners in Flight. Accessed at: http://www.prbo.org/calpif/plans.html *
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Appendix 1
Initial Study, Upper York Creek Restoration Project Initial Study
Upper York Creek Ecosystem Restoration a joint project of City of St. Helena and U.S. Army Corps of Engineers
Napa County, California
CEQA Lead Agency City of St. Helena 1480 Main Street St. Helena, CA
Contact: Jonathon Goldman Director of Public Works/City Engineer 707-968-2658
Prepared by Prunuske Chatham, Inc. P.O. Box 868 Occidental, CA 95465
Contact: Kathie Lowrey Senior Environmental Planner 707-874-0100
September 2006 Upper York Creek Ecosystem Restoration Administrative Draft Initial Study
PREPARERS OF THE INITIAL STUDY
This initial study was prepared for the City of St. Helena by Prunuske Chatham, Inc.. Individuals who contributed to this study include:
CITY OF ST. HELENA Jonathon Goldman, Director of Public Works/City Engineer Others?
PRUNUSKE CHATHAM, INC. Kathie Lowrey, Senior Environmental Planner Laura Saunders, Environmental Planner I Aimee Crawford, Environmental Planner II
Technical information was provided: Steven Chatham, Principal Lauren Hammack, Hydrologist/Fluvial Geomorphologist Jon Mann, PE, Senior Civil Engineer Jennifer Michaud, Senior Biologist
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Acronyms and Abbreviations
ARB Air Resources Board ATCM Airborne Toxic Contaminant Measure BAAQMD Bay Area Air Quality Management District CDFG California Department of Fish and Game CEQA California Environmental Quality Act CFR Code of Federal Regulations City City of St. Helena Corps U.S. Army Corps of Engineers CRLF California red-legged frog CNPS California Native Plant Society DWR Department of Water Resources EIR Environmental Impact Report ESA Endangered Species Act MPN Most Probable Number (an estimate of bacterial population) NEPA National Environmental Policy Act NMFS NOAA Fisheries National Marine Fisheries Service NOAA National Oceanic & Atmospheric Administration NOP Notice of Preparation NTU nephelometric turbidity units PM10 particulate matter less than 10 microns PM2.5 particulate matter less than 2.5 microns ppb parts per billion pphm parts per hundred million ppm parts per million SFBRWQCB San Francisco Bay Regional Water Quality Control Board SCH California State Clearinghouse SHPO State Historic Preservation Officer µg/m3 microgram USGS United States Geological Survey
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TABLE OF CONTENTS Page PREPARERS OF THE INITIAL STUDY ...... i ACRONYMS AND ABBREVIATIONS ...... ii PROJECT OVERVIEW...... 1 Project Title ...... 1 Lead Agency Name and Address ...... 1 Contact Person and Phone Number ...... 1 Project Location...... 1 Project Federal Sponsor's Name and Address ...... 1 Project Non-federal Sponsor's Name and Address ...... 1 Zoning ...... 2 Project Description ...... 3 Existing Conditions ...... 6 Other Public Agencies Whose Approval Is Required...... 7 NEPA Review ...... 7 CEQA Responsible and Trustee Agencies...... 7 Other Agencies with Jurisdiction by Law...... 7 Other Commenting Agencies ...... 7 Environmental Factors Potentially Affected...... 8 DETERMINATION ...... 8 AFFECTED ENVIRONMENT AND POTENTIAL ENVIRONMENTAL CONSEQUENCES...... 10 Aesthetics...... 10 Affected Environment ...... 10 Standards...... 11 Environmental Consequences ...... 11 Agricultural Resources ...... 13 Affected Environment ...... 13 Standards...... 14 Environmental Consequences ...... 14 Air Quality...... 15 Affected Environment ...... 15 Standards...... 17 Environmental Consequences ...... 17 Biological Resources...... 19 Affected Environment ...... 19
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Standards...... 23 Environmental Consequences ...... 24 Cultural Resources ...... 25 Affected Environment ...... 25 Standards...... 26 Environmental Consequences ...... 27 Geology and Soils ...... 28 Affected Environment ...... 29 Standards...... 29 Environmental Consequences ...... 30 Hazards and Hazardous Materials ...... 31 Affected Environment ...... 33 Standards...... 33 Environmental Consequences ...... 33 Hydrology and Water Quality...... 34 Affected Environment ...... 35 Standards...... 36 Environmental Consequences ...... 37 Land Use and Planning...... 38 Affected Environment ...... 38 Standards...... 38 Environmental Consequences ...... 38 Mineral Resources ...... 39 Noise...... 40 Affected Environment ...... 40 Standards...... 41 Environmental Consequences ...... 41 Population and Housing...... 42 Affected Environment ...... 42 Standards...... 42 Environmental Consequences ...... 42 Public Services...... 43 Affected Environment ...... 43 Standards...... 43 Environmental Consequences ...... 44 Recreation ...... 45 Affected Environment ...... 45 Standards...... 46
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Environmental Consequences ...... 46 Transportation and Traffic ...... 47 Affected Environment ...... 47 Standards...... 48 Environmental Consequences ...... 48 Utilities and Service Systems ...... 50 Affected Environment ...... 51 Standards...... 51 Environmental Consequences ...... 51 MANDATORY FINDINGS OF SIGNIFICANCE...... 52 REFERENCES...... 54
FIGURES Figure 1: Project Location Map
Figure 2: Project Area Earthquake Shaking Intensity
Figure 3: Project Area Landslide Location Map
Figure 4: Project Area Liquefaction Potential Map
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PROJECT OVERVIEW
Project Title Upper York Creek Ecosystem Restoration
Lead Agency Name and Address City of St. Helena 1480 Main Street St. Helena, CA 94574
Contact Person and Phone Number Jonathon Goldman, Director of Public Works/City Engineer (707) 968-2658
Project Location The main project location is at the Upper York Creek Dam and Reservoir (Upper St. Helena Dam). The reservoir is located at 38º 30’ 48” N, 122º 30’ 9” W, in the SW ¼, Section 26, Range 6 West, Township 8 North, Mt. Diablo Base and Meridian of the St. Helena Quadrangle, St. Helena, Napa County, California (see Figure 1). Several nearby sites, including a private upland vineyard, Lower York Creek Reservoir, Fulton Lane, and Clover Flat landfill, may be utilized for reuse or disposition of materials removed during project activities.
Project Federal Sponsor's Name and Address U.S. Army Corps of Engineers San Francisco District, South Pacific Division 333 Market Street San Francisco, CA 94105-2197
Project Non-federal Sponsor's Name and Address City of St. Helena 1480 Main Street St. Helena, CA 94574
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Zoning AW (Agriculture, Watershed or Open Space Lands)
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Project Description
The project will involve alteration or removal of the Upper St. Helena Dam on York Creek and restoration of the decommissioned reservoir into natural creek channel and native riparian corridor. The proposed removal or alteration of the dam is a joint project of the City of St. Helena (City) and the U.S. Army Corps of Engineers (Corps). The purpose of the project is to prevent potentially detrimental sediment releases. The project will also allow fish passage to two upstream miles of spawning and rearing habitat for steelhead and restoration of approximately three acres of riparian and aquatic habitat. Additionally, the project will provide a long-term solution to prevent dam breach/failure and consequent catastrophic downstream flooding and debris flow.
York Creek was first dammed in 1871. The current dam was built upstream of the original reservoir in 1900 to extend the City’s water delivery system to match its expanding development (Eastman, 2003). The Upper St. Helena Dam is an earthen structure, 140 feet wide and 50 feet high, with basaltic rip rap reinforcement on both faces. The outlet is a drop snorkel that collects water near the downstream edge of the reservoir and discharges it through a pipe in the bottom center of the dam. In 1933, a concrete overflow spillway was added along the eastern edge of the reservoir and dam, immediately adjacent to Spring Mountain Road.
All of the action alternatives include riparian and in-stream habitat restoration of the area disturbed by the original creation of the dam and reservoir. All of the action alternatives except creation of a fish ladder will include restoration of the natural hydrologic processes of York Creek, including moving sediment downstream in a routine way. Based upon a feasibility analysis by the Corps (DPR 2006), there are currently four alternatives being considered:
• No project – The dam would remain unaltered. No habitat restoration would occur. The City of St. Helena would need to continue maintenance dredging to avoid destructive sediment releases. • Total removal of the dam – This alternative would allow creation of a 30-foot wide floodplain bench. It would require stabilization of the hillsides and Spring Mountain Road. 100% of the sediment currently accumulated behind the dam would be removed. • Small notch in the dam – This alternative allows restoration of the natural
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hydrologic functions of York Creek but without a floodplain bench. 95% of the sediment accumulated behind the dam would be removed. It is the most geologically stable alternative that allows restoration of York Creek’s hydrology. • Fish ladder through the dam – This alternative would create a concrete step- pool/weir fish ladder cut into the dam. 37% of the sediment accumulated behind the dam would be removed. The fish ladder would require on-going maintenance to prevent it from becoming clogged with sediment.
The City will determine the reuse and/or disposition of materials removed from the dam and reservoir according to the project alternative selected and, therefore, the amount of material to be placed. The material will be placed in some combination of the following locations:
• Use at a nearby private upland vineyard. • Use in a City of St. Helena flood control project. • Use in other City of St. Helena project(s). • Storage in the Lower York Creek Reservoir. • Disposal at an approved facility.
The vineyard currently under consideration for reuse is Spring Mountain Vineyard at 2805 Spring Mountain Road. Spring Mountain Vineyard lies just west of the reservoir and has access from Spring Mountain Road within 0.5 miles both north and south of the project. Spoils would be placed on a fallow vineyard as a soil amendment and graded to match the existing slope.
The City of St. Helena is involved in preliminary negotiations with landowners and assessment of a flood control project at Fulton Lane within City limits. If agreement is reached with private landowners, materials removed from York Creek as part of project activities might be reused at Fulton Lane. Placement of spoils in City projects including flood control, if appropriate, will be investigated as part of the preparation of the project’s Environmental Impact Report (EIR).
The Lower York Creek Reservoir currently has a storage capacity of 200 acre-feet. The water is used for agricultural irrigation. The water level would be temporarily dropped, spoils would be placed along the edge or bottom, and then the water would be allowed to return to its initial level. It is estimated that 6 to 12 acre-feet of spoils might be placed in the lower reservoir (3.5-7% of the reservoir’s capacity) (Corps
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DPR, 2006).
The approved disposal facility being considered is Clover Flat landfill, located within 9 miles of the project site. Conversation with landfill management has been initiated regarding how much of the spoils can reasonably be accommodated. Planning will continue to assure that spoils placed at the landfill do not overtax its capacity.
The exact distribution of the spoils will depend on which of the project alternatives is selected because each would each generate different amounts. It will also depend on whether the City does proceed with a project at Fulton Lane and/or other projects. Full investigation of potential reuse and disposition sites will occur as part of EIR preparation.
The “no project” alternative would not generate spoils immediately under this project. However, there are approximately 28,000 cubic yards of sediment in the reservoir that will require maintenance, and an estimated 1,000 to 1,500 cubic yards more will be deposited each year under current conditions (Corps DPR, 2006).
It is estimated that the total removal of the dam would generate 45,000 cubic yards of spoils to remove both the dam and the sediments behind the dam. Notching the dam would generate approximately 38,000 cubic yards of spoils. Both removing and notching the dam are one-time events.
Construction of the fish ladder would generate approximately 19,000 cubic yards of spoils, and some maintenance cleaning will be required. It is anticipated that the vineyard could absorb a maximum of 12,000 cubic yards of material, the lower reservoir 15,000 cubic yards, and Clover Flat 4,000 cubic yards (Corps DPR, 2006). The amount that may be used in City projects is not yet determined. Another 4,000 cubic yards can remain at the site to be used in the restoration.
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Existing Conditions
York Creek runs approximately 7.24 miles from its headwaters to its confluence with the Napa River (Corps EA, 2006). It descends steeply over the first portion of its range then flattens out as it crosses the floodplain of the Napa River. It drains a watershed of approximately 4.4 square miles (Watershed Information and Conservancy Center of Napa County).
According to the Napa County Resource Conservation District, York Creek is one of the most significant spawning and rearing streams in the Napa River watershed for Central California Coast ESU steelhead, which are listed as threatened under the federal Endangered Species Act. The Napa River watershed is one of the most significant anadromous fish streams tributary to San Francisco Bay.
At the site of the upper York Creek reservoir, the creek traverses a steep valley cut from serpentinite and sheared shale. The area is geologically unstable. Vegetation is a mixture of hardwood/conifer forests and vineyards. There is riparian vegetation along the banks of York Creek, and some has grown up in the sediment deposits in the reservoir since it was last dredged. There is currently approximately 28,000 cubic yards of sediment in the reservoir, essentially eliminating any water storage capacity (Corps DPR, 2006).
The reservoir is immediately adjacent to Spring Mountain Road with the right wall of the spillway (looking upstream) providing structural support to the road. Spring Mountain Road connects St. Helena to Santa Rosa in Sonoma County. While not designated as scenic, it is a beautiful, 2-lane road that is a popular part of Napa Valley bicycle rides.
There are approximately 24 small wineries along Spring Mountain Road. These vineyards comprise the Spring Mountain area, known for high-quality, mountain- grown cabernets. They are a tourist destination.
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Other Public Agencies Whose Approval Is Required
NEPA Review The U.S. Army Corps of Engineers is the lead agency under the National Environmental Policy Act (NEPA).
CEQA Responsible and Trustee Agencies Bay Area Air Quality Management District California Department of Fish and Game San Francisco Bay Regional Water Quality Control Board NOAA National Marine Fisheries Service United States Fish and Wildlife Service
Other Agencies with Jurisdiction by Law Napa County
Other Commenting Agencies Caltrans Napa County Resource Conservation District
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Environmental Factors Potentially Affected
The environmental factors checked below would be potentially affected by this project, involving at least one impact that is a "Potentially Significant Impact" as indicated by the checklist on the following pages.
Aesthetics X Agricultural Air Quality Resources
X Biological Resources X Cultural Resources X Geology /Soils
X Hazards & X Hydrology / Water Land Use / Hazardous Materials Quality Planning
Mineral Resources X Noise Population / Housing
Public Services Recreation X Transportation/ Traffic
Utilities / Service X Mandatory Findings of Significance Systems
Determination
On the basis of this initial evaluation:
I find that the proposed project MAY have a significant effect on the environment, and an ENVIRONMENTAL IMPACT REPORT is required.
Signature Date
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Signature Date
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AFFECTED ENVIRONMENT AND POTENTIAL ENVIRONMENTAL CONSEQUENCES
Aesthetics
Potentially Less Than Less Than No Would the project: Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Have a substantial adverse effect on a scenic X vista?
b) Substantially damage scenic resources, X including, but not limited to, trees, rock outcroppings, and historic buildings within a state scenic highway?
c) Substantially degrade the existing visual X character or quality of the site and its surroundings?
d) Create a new source of substantial light or X glare which would adversely affect day or nighttime views in the area?
Affected Environment Upper York Creek Dam and Reservoir (Upper St. Helena Dam) is located on Spring Mountain Road, which connects St. Helena with Santa Rosa in Sonoma County. The road is also used by tourists visiting the numerous local wineries. It is not a designated state scenic highway, but it is a very beautiful, twisting, 2-lane road that traverses a narrow canyon through riparian and oak forests, along with vineyards and scattered grasslands.
Once Spring Mountain Road leaves the vicinity of downtown St. Helena, there is little visible development. The character of the area surrounding the project site is riparian
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forest along the scenic road. The City of St. Helena General Plan calls for preserving and enhancing riparian corridors such as this, partly for their visual amenity.
Proposed sediment reuse or disposal sites include Lower York Creek Reservoir, Fulton Lane, a fallow area of local vineyard, and Clover Flat landfill. The lower reservoir is not visible from Spring Mountain Road or from any public spot. However, a neighbor has a gazebo with a view of the reservoir.
Standards Visual effects are considered significant if the project would have a substantial, permanent, adverse impact on the scenic or visual character of the project area and surrounding environment. Source: existing City of St. Helena standards as stated in Initial Study for the York Creek Diversion Modification Project (DWR, 2002).
Environmental Consequences There are four sites that may be affected by the project: the Upper York Creek Reservoir, Lower York Creek Reservoir, Fulton Lane, and the upland private vineyard. None of these sites are on or visible from a state scenic highway. The only location being considered for the project that is part of a scenic vista is the lower reservoir. The adjacent neighbor’s view would be temporarily impacted during placement of spoils. However, no long-term impact would result.
At the Upper York Creek Reservoir, the potential impacts are to the vista from Spring Mountain Road. The project will have no permanent adverse effect on the scenic nature of the area. In fact, long-term effects will be beneficial because the project includes restoration of currently degraded areas. Planting with native riparian species will occur in three zones (bank, terrace, upland) to provide diversity of habitat. Approximately 20 trees will need to be removed; revegetation will involve installation of 475 medium and large tree species, including maple, box elder, Oregon ash, coastal redwood, tanbark oak, Douglas fir, valley oak, California bay laurel, madrone, and coast live oak (Corps EA, 2006).
Potential visual impacts to the lower reservoir are limited to construction-related activities. After placement of spoils for storage, the water level of the reservoir will be returned to pre-existing conditions. The seasonal nature of vegetation will remain, and all project-disturbed areas will be revegetated with native species.
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Any change in the visual character of the other potentially affected locations will be brief, only during construction. It will not, therefore, be significant. No light or glare will be created as construction will be performed only during the daylight.
The riparian corridor and forested sections of Spring Mountain Road are approximately 6.2 miles long (site measurements). The section visually affected by construction is 0.3 miles, or less than 5%, so the project will not substantially affect the visual character of the site and surroundings. No other projects are currently proposed that impact the same stretch of Spring Mountain Road (SCH, 2006). There will not be cumulatively considerable adverse impacts to aesthetics from the project.
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Agricultural Resources
In determining whether impacts to agricultural resources are significant environmental effects, Potentially Less Than Less Than No lead agencies may refer to the California Significant Significant Significant Impact Agricultural Land Evaluation and Site Impact with Impact Assessment Model (1997) prepared by the Mitigation California Dept. of Conservation as an optional Incorporation model to use in assessing impacts on agriculture and farmland. Would the project:
a) Convert Prime Farmland, Unique Farmland, or X Farmland of Statewide Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency, to non- agricultural use?
b) Conflict with existing zoning for agricultural X use, or a Williamson Act contract?
c) Involve other changes in the existing X environment which, due to their location or nature, could result in conversion of Farmland, to non-agricultural use?
Affected Environment Several options are being evaluated by the City of St. Helena for disposition of the sediment removed from the Upper York Creek Dam and Reservoir. The areas of the dam and reservoirs are zoned for agriculture, watershed, or open space land uses, however, they have not recently been utilized for agriculture except to provide water for irrigation. The private, fallow vineyard is zoned for agricultural use, and reuse of sediments from York Creek after amendment will allow for replanting of grapes.
Should the option to reuse some of the materials along a portion of Fulton Lane for flood control be agreed upon by the City and the private landowners involved, some impacts to agricultural lands may occur. A portion of Fulton Lane is designated for agricultural land use in the City of St. Helena General Plan and is classified as prime farmland as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency. According to the City of St. Helena planning department, none of the properties in the Fulton Lane area that may be affected by the project are under Williamson Act contract.
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Standards Project impacts were considered significant if they would conflict with existing zoning for agricultural use or convert prime farmland.
Environmental Consequences Any alteration or removal of the dam and accumulated sediments will not conflict with the existing zoning. The upper dam area will be restored to its original watershed characteristics, and it will continue to be open space. The lower reservoir will be returned to its original level and will continue to be used as a water supply for the City of St. Helena.
Placement of dam and sediment materials at Fulton Lane may impact limited portions of the roadway and adjacent agricultural lands, which are currently planted in vineyards. One possible project option involves elevating a maximum of 1,600 feet of Fulton Lane to minimize flooding impacts to the roadway. This road elevation may require conversion of a maximum of 12-18 feet of the agricultural land on either side of the roadway from agricultural uses to road bank.
These activities do not conflict with existing zoning for agricultural use, and none of the properties on Fulton Lane that may be affected by the project are under Williamson Act contracts. A portion of Fulton Lane is classified as prime farmland, and the conversion of agricultural land would be a potentially significant impact on agricultural resources. This impact may be reduced to less than significant if the reuse option at the Fulton Lane is not utilized.
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Air Quality
Where available, the significance criteria Potentially Less Than Less Than No established by the applicable air quality Significant Significant Significant Impact management or air pollution control district may Impact with Impact be relied upon to make the following Mitigation determinations. Would the project: Incorporation
a) Conflict with or obstruct implementation of the X applicable air quality plan?
b) Violate any air quality standard or contribute X substantially to an existing or projected air quality violation?
c) Result in a cumulatively considerable net X increase of any criteria pollutant for which the project region is non-attainment under an applicable federal or state ambient air quality standard (including releasing emissions which exceed quantitative thresholds for ozone precursors)?
d) Expose sensitive receptors to substantial X pollutant concentrations?
e) Create objectionable odors affecting a X substantial number of people?
Affected Environment The Napa Valley is a long, north-south valley, largely surrounded by mountains except at the southern end where the Napa River drains into San Pablo Bay. Wind direction in the area is controlled by topography, climate, and the proximity of San Francisco Bay. During the summer when work will occur, warm inland temperatures cause the air to rise, sucking in cool air off the Pacific Ocean through the Golden Gate. This process often results in high winds on San Francisco Bay. The same process happens in microcosm at the south end of the Napa Valley. Heating on the valley floor draws air in from the main body of San Francisco Bay, across San Pablo Bay, and up the valley. Winds in the area are much gentler, however, with almost 50% of the winds below 4 mph (Jones & Stokes and EDAW, Inc). On summer evenings, the wind often reverses direction.
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York Creek runs through a narrow valley on the west side of the Napa Valley. During summer days, the combination of valley floor heat and prevailing wind direction causes air to flow up the York Creek valley. This will generally mean that air flow is from the project site toward less densely populated sites. Identified possible reuse or disposal sites are within the same creek valley or on the valley floor north of the City, which again will tend to mean that air flow is away from the densely populated areas.
Air quality and emissions are regulated in California by the Air Resources Board (ARB). Under the ARB, the state is divided into 35 local air districts that have primary responsibility for controlling air pollution from stationary sources. The project will take place under the jurisdiction of the Bay Area Air Quality Management District (BAAQMD). The District's jurisdiction encompasses all of seven counties (Alameda, Contra Costa, Marin, San Francisco, San Mateo, Santa Clara, and Napa) and portions of two others (southwestern Solano and southern Sonoma). Each air quality management district must assess air quality for 6 criteria pollutants: ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, coarse particulate matter - particulate matter smaller than 10 microns (PM10), and particulate matter smaller than 2.5 microns (PM2.5). For each of these pollutants, the basin is designated as being attainment (below the regulatory limit) or non-attainment for both state and federal standards. Attainment standards can be used to assess the air quality of sub-basins like the Napa Valley. Table 1 below shows the status of the greater project area. In 2004, the most recent year for which full data is available, Napa County met air quality standards in every area except coarse particulates (PM10).
Table 1. Air Quality in the San Francisco Bay Area and Napa County Ozone Carbon Nitrogen Sulfur PM10 PM2.5 (pphm) monoxide dioxide Dioxide (µg/m3) (µg/m3) (ppm) (pphm) (ppb) 1 hr 8 hr 1 hr 8 hr 1 hr Ann 24 hr Ann 24 hr Ann 24 hr Ann National Attainment --- 8 35 9 ---- 5.3 140 30 150 50 65 15 Standard California 9 --- 20 9 25 --- 40 --- 50 20 --- 12 Attainment Standard Bay Area Nat --- N A A --- A A --- A U A A Attainment Cal N A A A A --- A A N N --- N Status (2004) Napa County Annual 9 7 3.7 2.0 6 1.1 ------60 20.7 ------Average (2004) Napa Nat --- A A A --- A ------A A ------County Attainment Cal A --- A A A ------N N ------
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Status A = attainment of an established air quality standard N = non-attainment
Standards Project impacts from particulates would be considered significant if construction activities generate more than 80 lbs/day of PM10 (ARB).
Project impacts from naturally occurring asbestos would be considered significant if cancer risks for maximally exposed individuals would increase by 10 in 1 million (BAAQMD).
Project impacts would be considered to be cumulatively considerable if the project would:
• Produce carbon monoxide concentrations above state or national standards. • Produce PM10 emissions above 80/lbs per day. • Have potential odor, toxics, or accidental release impacts. (BAAQMD)
Environmental Consequences The air pollutant of most concern from construction projects is generally particulate matter, specifically particulates between 2.5 and 10 µg/m3 known as PM10. Construction site sources for PM10 on this project include dust from grading, excavation and other earth moving activities, and emissions from construction equipment.
The total area disturbed by construction would be less than 3 acres. Using the ARB emission factor of 0.11 ton/acre-month (Rulemaking informal: 2002-09 methodologies), the total PM10 emissions from the project would be 3,960 lbs. Figuring a 5-day work week, project PM10 emissions would be about 38 lbs/day (see calculations in box below). Since this is below the 80 lbs/day threshold set by the ARB, there will not be a significant effect from coarse particulate emissions.
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Calculation of projected PM10 emissions (based on BAAQMD emission factors for construction using best management practices to control fugitive dust):
( 0.11 ton ) ( 3 acres ) ( 6 months ) ( 2000 lbs ) = 3,960 lbs total project PM10 (Acre-month) ( 1 ton)
3,960 lbs = 38 lbs/day PM10 emissions 105 days
However, the project may have a cumulatively significant impact because there may be toxic emissions generated by construction disturbance of naturally-occurring sources, as set by the BAAQMD. These impacts are discussed in the hazards section below. If needed, permit(s) from BAAQMD will be obtained, and all conditions of the permit(s) will be incorporated into the project description.
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Biological Resources
Would the project: Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Have a substantial adverse effect, either X directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service?
b) Have a substantial adverse effect on any X riparian habitat or other sensitive natural community identified in local or regional plans, policies, regulations or by the California Department of Fish and Game or US Fish and Wildlife Service?
c) Have a substantial adverse effect on federally X protected wetlands as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means?
d) Interfere substantially with the movement of X any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites?
e) Conflict with any local policies or ordinances X protecting biological resources, such as a tree preservation policy or ordinance?
f) Conflict with the provisions of an adopted X Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan?
Affected Environment Upper Reservoir
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The Upper York Creek Reservoir is located in the York Creek watershed west of the City of St. Helena, thence the Napa River, Napa County. Habitats surrounding the project site consist of steep, heavily forested habitat (conifer-oak-bay forest), riparian habitat, and open reservoir. Land uses include open space, residential, and agriculture (vineyards).
The riparian and forested woodlands surrounding the site are dense to sparsely vegetated. The canopy is dominated by oaks (Quercus sp.), bigleaf maple (Acer macrophyllum), California bay (Umbellularia californica), Douglas fir (Pseudotsuga menziesii), willow (Salix sp.), and white alder (Alnus rhombifolia). The understory is sparsely to heavily vegetated. The downstream embankment is dominated by Himalayan blackberry (Rubus discolor), unidentifiable oak saplings, scotch broom (Cytisus scopariusa), coyote brush (Baccharis pilularis), periwinkle (Vinca major), and fennel (Foeniculum vulgare). Several medium size (6 to 8” dbh) willows and white alders occur within the impoundment itself. There are a few isolated patches of emergent vegetation present, especially along the right bank (looking downstream). These include mostly Himalayan blackberry, willow, and white alder. Giant horsetail (Equisetum telmateia) occurs along the edge of the impoundment in a few locations.
The upper dam site provides nesting opportunities, food, and shelter and may serve as corridors or islands during migration for a variety of fish and wildlife species, including resident and migratory birds, mammals, reptiles, amphibians, and invertebrates. There is a small population of naturalized bullfrogs (Rana catesbeiana). Despite the presence of bullfrogs, California red-legged frog (Rana aurora draytonii, CRLF) may occur in small numbers within the project area or within close proximity. However, habitat for CRLF at the upper dam is marginal. Surveys for CRLF were performed at the upper reservoir in 2001 and 2006 with negative findings. Steelhead (Oncorhynchus mykiss) are known to occur downstream of the dam in lower York Creek, and resident rainbow trout occur upstream. Northern spotted owl (Strix occidentalis caurina) are also known to occur within the woodlands surrounding the reservoir. Based on the high quality habitat, the potential for occurrence of both special-status plant and animal species on the project site is considered high. Further surveys will be conducted as part of the EIR process.
Lower Reservoir The lower reservoir is located along Spring Mountain Road west of the town of St. Helena, Napa County, downstream of the upper dam in the York Creek watershed. The primary communities occurring within the lower reservoir and immediate area are foothill pine-oak woodland, non-native grassland, and freshwater marsh. Land uses
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surrounding the site include open space, residential, roadways, and agriculture (vineyards).
Foothill pine-oak woodland, composed primarily of the foothill pine series and blue oak series, occurs on well-drained uplands surrounding the reservoir. Native trees dominate the canopy, including foothill pine (Pinus sabiniana), blue oak (Q. douglasii), coast live oak (Q. agrifolia), California black oak (Q. kelloggii), madrone (Arbutus menziesii), California buckeye (Aesculus californica), and occasional Douglas-fir (Pseudotsuga menziesii var. menziesii) and valley oak (Q. lobata). The understory is composed of a mix of shrubs and herbs, including toyon (Heteromeles arbutifolia), manzanita (Arctostaphylos sp.), coyote brush, sticky monkeyflower (Mimulus aurantiacus), poison oak (Toxicodendron diversilobum), deer weed (Lotus scoparius), hairy honeysuckle (Lonicera hispidula), Douglas iris (Iris douglasiana), and California man-root (Marah fabaceus).
Non-native grassland, composed of a phase of the California annual grassland series, occurs on berms fringing the lower reservoir and in other well-drained uplands adjacent to foothill pine-oak woodland. Dominant species are a mix of native and non- native grasses and forbs. The natives include clarkia (Clarkia sp.), blue-eyed-grass (Sisyrinchium bellum), harvest brodiaea (Brodiaea elegans), California poppy (Eschscholzia californica), soap plant (Chlorogalum pomeridianum), and purple needlegrass (Nassella pulchra). The non-natives include wild oats (Avena sp.), Italian ryegrass (Lolium multiflorum), soft chess (Bromus hordeaceus), hedgehog dogtail (Cynosurus echinatus), rose clover (Trifolium hirtum), English plantain (Plantago lanceolata), and Italian thistle (Carduus pycnocephalus).
Freshwater marsh, composed of the bulrush-cattail series, occurs along the reservoir’s fringes. Dominant species are primarily wetland-classified herbs, including California bulrush (Scirpus californicus), narrow-leaved cattail (Typha angustifolia), spikerush (Eleocharis macrostachya), iris-leaved rush (Juncus xiphioides), and tall flatsedge (Cyperus eragrostis), with occasional riparian trees such as Fremont cottonwood (Populus fremontii ssp. fremontii) and narrow-leaved willow (S. exigua). Wetland-classified plant species, such as rabbitsfoot grass (Polypogon monspeliensis) and hyssop loosestrife (Lythrum hyssopifolium), along with wetland hydrology indicators, are also present in two compacted depressions along the access road.
The freshwater marsh and reservoir within the project site provide excellent resources for wildlife. The non-native grasslands provide marginal habitat for native wildlife species. Habitat elements suitable for CRLF survival (basking, foraging, breeding, and
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aestivation habitat) are present at the lower reservoir. Surveys for CRLF were performed at the lower reservoir in 2006 with negative findings.
The lower reservoir provides high quality habitat for special-status plants identified from the project site region during a background literature search. Based on the high quality habitat, the potential for occurrence of both special-status plant and animal species on the project site is considered high. Further surveys will be conducted as part of the EIR process.
Spring Mountain Vineyard The Spring Mountain Vineyard site is a fallow, terraced vineyard located at approximately 1,170 feet in elevation. A swale bisects two sloping hillsides into the eastern and western sections. The primary plant communities occurring within the project site and immediate area are non-native grassland and mixed evergreen forest. Land uses surrounding the site include vineyard, winery facilities, and access roads.
Non-native grassland, composed of a highly disturbed phase of the California annual grassland series, is the dominant plant community on the project site and covers terraced hillsides throughout the fallow vineyard. Dominant species are non-native grasses and forbs adapted to disturbance, including ripgut brome (Bromus diandrus), wild oats (Avena sp.), hedgehog dogtail (Cynosurus echinatus), vulpia (Vulpia sp.), geranium (Geranium dissectum), barley (Hordeum murinum), rose clover (Trifolium hirtum), common dandelion (Taraxacum officianale), prickly lettuce (Lactuca serriola), common vetch (Vicia sativa), field bindweed (Convolvulus arvensis), and bristly ox- tongue (Picris echioides). Several small coyote brush (Baccharis pilularis) occur along the edges of the grassland.
Mixed evergreen forest, composed primarily of the Douglas-fir series, occurs on the fringes of non-native grassland outside the fallow vineyard. Douglas-fir (Pseudotsuga menziesii var. menziesii) dominates the canopy, with a subcanopy of madrone (Arbutus menziesii), coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and California buckeye (Aesculus californica). The mixed understory consists primarily of native shrubs including poison oak (Toxicodendron diversilobum), toyon (Heteromeles arbutifolia), coyote brush, and buckbrush (Ceanothus cuneatus).
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West of the swale, within non-native grassland habitat, two small, highly disturbed areas (approximately 300 and 500 square feet) were observed. These areas appear seasonally wet, based on the presence of algal mats and other indicators of wetland hydrology, due to minor surface and subsurface discharge. They support wetland- classified plant species, such as rabbitsfoot grass (Polypogon monspeliensis), spreading rush (Juncus patens), fireweed (Epilobium sp.), and sedge (Carex sp.), along with two small individuals of narrow-leaved cattail (Typha angustifolia) and one red willow (Salix laevigata). No special-status plant species were observed during the field survey. These seasonally wet areas to the west of the swale provide limited habitat due to their size and ephemeral nature.
The non-native grasslands provide marginal habitat for native wildlife species. In general, they provide habitat for ground foraging resident and migratory birds. The adjacent mixed evergreen forest support a large variety of wildlife species, however, this habitat is outside the area of disturbance.
Fulton Lane Biological studies have not yet been performed for Fulton Lane. These studies will be performed if it becomes more likely that the area will, in fact, be used for disposition.
Standards Impacts to biological resources were considered significant if they would: • Directly or indirectly disrupt or impair the growth, survival, or reproductive success for species listed or proposed for listing as threatened or endangered under the federal ESA or California ESA. • Directly or indirectly disrupt or impair the growth, survival, or reproductive success of other special-status species such as CNPS 1B or 2 listed plants or California Species of Special Concern. • Substantially reduce the quality or quantity of important habitat for special- status species.
Source: existing City of St. Helena standards as stated in Initial Study for the York Creek Diversion Modification Project (DWR, 2002).
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Environmental Consequences Based on biological studies to date, there may be potentially significant impacts to special status species and to jurisdictional wetlands. Care will be taken to design the project to avoid as many impacts as possible. Further studies will be performed as part of the EIR to determine what avoidance and/or mitigation measures are necessary. One of the primary purposes of this project is to enhance biological resources by improving and extending salmonid habitat on York Creek. The project will result in an increase in multi-story native riparian vegetative cover that will provide high quality habitat for a number of aquatic, avian, and terrestrial species.
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Cultural Resources
Potentially Less Than Less Than No Would the project: Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Cause a substantial adverse change in the X significance of a historical resource as defined in '15064.5?
b) Cause a substantial adverse change in the X significance of an archaeological resource pursuant to '15064.5?
c) Directly or indirectly destroy a unique X paleontological resource or site or unique geologic feature?
d) Disturb any human remains, including those X interred outside of formal cemeteries?
Affected Environment
Ethnographic Setting The project area lies within the territory historically occupied by the tribal group known as the Wappo. which belong to the Yukian language family, a very small language family that also includes the Yuki, the Coast Yuki, and the Huchnom tribal groups. The territory of the Wappo is subdivided according to five mutually intelligible dialects that were spoken by the Wappo tribal group: the Western, Northern, Central, Southern, and Clear Lake groups. The project area lies in the Central Wappo territory. Source: Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project (City of St. Helena, 2004).
Historic Setting The Upper York Creek Dam was constructed in 1900, and the adjacent concrete spillway was added in 1933. The dam was essential to the growth of the City of St. Helena in the early 20th century because it expanded the capacity of the original water delivery system, making more water available for the increasing commercial and residential uses, as well as for fire protection.
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A cultural resources study of the project’s area of potential effects was undertaken as part of the Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project (DWR, January 2004, quoting Eastman, 2003).
Prehistoric Archaeological Resources As part of the cultural resources study discussed above, a survey for potential archeological resources in the project area was conducted in 2001, including a records and literature search, a search of the Native American Heritage Commission’s Sacred Lands File, and a field survey. No archaeological resources were identified within the proposed project area, and a Negative Archaeological Survey Report was prepared. Source: Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project (City of St. Helena, 2004).
Historical Resources The Upper St. Helena Dam was formally evaluated pursuant to Section 106 of the National Historic Preservation Act, as amended, and its implementing regulations (36 CFR 800, December 2000) and Section 15064.5 of CEQA by Bright Eastman in the 2003 Historical Resources Evaluation Report attached to the Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project. According to Eastman, the dam appears eligible for the National Register under Criterion A, at a local level of significance in the area of community development, and may also be considered an historical resource for the purposes of CEQA. It is considered eligible for listing on the California Register of Historical Resources pursuant to California Public Resources Code Section 5024.1(d) (1).
Standards A project would be considered significant if any historical or archaeological resource were abolished or altered in a way to make the relevant history unavailable. Specifically, the project would be considered significant if it would eliminate an important example of a major period of California history or prehistory, such as the Upper St. Helena Dam.
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Environmental Consequences
Prehistoric Archaeological Resources The archaeological survey of the project area did not reveal the presence of any prehistoric archaeological resources. Therefore, impacts to prehistoric archaeological resources are not anticipated. Project construction personnel will receive a pre-project briefing of potentially-occurring prehistoric resources and measures to avoid impacts. Should prehistoric resources be uncovered while conducting project activities, all work will temporarily cease until the findings can be assessed by a qualified archaeologist and an appropriate course of action is determined with the State Historic Preservation Officer (SHPO).
Historical Resources There are three proposed action alternatives: full removal of the dam, alteration of the dam through a small notch, or construction of a fish ladder through the dam. All of these proposed project alternatives are being undertaken for purposes of protecting lower York Creek from sediment releases and flooding and for restoring anadromous fish passage. Each would substantially change the dam’s structure, resulting in significant effects on the dam’s historic feeling, design, and association. Specific mitigation will be determined during the EIR process; measures will include photo documentation of the dam prior to alteration. The appropriate scope of documentation will be based on the results of consultation with historical experts. The intent of the documentation will be to preserve the physical information about this historic property.
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Geology and Soils
Would the project: Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Expose people or structures to potential substantial adverse effects, including the risk of loss, injury, or death involving:
i) Rupture of a known earthquake fault, as X delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42.
ii) Strong seismic ground shaking? X
iii) Seismic-related ground failure, including X liquefaction?
iv) Landslides? X
b) Result in substantial soil erosion or the loss of X topsoil?
c) Be located on a geologic unit or soil that is X unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse?
d) Be located on expansive soil, as defined in X Table 18-1-B of the Uniform Building Code (1994), creating substantial risks to life or property?
e) Have soils incapable of adequately supporting X the use of septic tanks or alternative waste water disposal systems where sewers are not available for the disposal of waste water?
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Affected Environment Although the entire San Francisco Bay Area is prone to earthquakes, ruptures of known faults are predicted to produce only moderate to strong shaking throughout the project area (ABAG; see Figure 2).
The upper portions of the York Creek watershed are steep and located on a mélange of sheared shale and serpentinite. This mixture is geologically unstable. Preliminary mapping indicates that the area of the upper reservoir is highly prone to landslides (ABAG; see Figure 3). At the upper reservoir, Spring Mountain Road travels along one side of a steep canyon, and there is a road cut that is undergoing small-scale debris flow. On the reservoir side, the road ends at the vertical wall of the spillway. Project plans include addressing landslide hazard at the upper reservoir site. However, it will be appropriate to address this issue thoroughly in the EIR.
The lower portion of the watershed is floodplain, composed of alluvial deposits from the Napa River. Alluvial deposits generally have higher susceptibility to liquefaction than other soils. As alluvial deposits get older, further away from the existing river or stream, they tend to settle and become more stable. This trend exists in the project area. Upland sites have very low liquefaction potential, much of the valley floor has moderate liquefaction potential, and just the area near the Napa River has high liquefaction potential (see Figure 4). As part of project development, issues involving geology and soils will be assessed in a site-specific way.
Standards Seismic Activity Project impacts would be considered significant if they are were subject to very strong seismic shaking and the project increased hazards to humans, property, or sensitive natural resources from that shaking.
Landslides Project impacts would be considered significant if they were to cause a substantial increase in landslide potential.
Soils Project impacts would be considered significant if they were to cause a substantial increase in soil erosion and loss of topsoil in the project area.
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Environmental Consequences Based on preliminary information, the project is not likely to have significant impacts from earthquake. However, if work were to be conducted at Fulton Lane, that area will need to be assessed on a site-specific basis to evaluate liquefaction potential and resulting hazards.
The EIR will include geologic assessment to determine whether the project will significantly increase landslide potential. It is not anticipated that this project will have significant impacts to soils or soil erosion. In fact, it is likely to reduce soil erosion in the riparian restoration area at the upper reservoir.
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Hazards and Hazardous Materials
Potentially Less Than Less Than No Would the project: Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Create a significant hazard to the public or the X environment through the routine transport, use, or disposal of hazardous materials?
b) Create a significant hazard to the public or the X environment through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment?
c) Emit hazardous emissions or handle hazardous X or acutely hazardous materials, substances, or waste within one-quarter mile of an existing or proposed school?
d) Be located on a site which is included on a list X of hazardous materials sites compiled pursuant to Government Code Section 65962.5 and, as a result, would it create a significant hazard to the public or the environment?
e) For a project located within an airport land use X plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project result in a safety hazard for people residing or working in the project area?
f) For a project within the vicinity of a private X airstrip, would the project result in a safety hazard for people residing or working in the project area?
g) Impair implementation of or physically X interfere with an adopted emergency response plan or emergency evacuation plan?
h) Expose people or structures to a significant risk X of loss, injury or death involving wildland fires, including where wildlands are adjacent to urbanized areas or where residences are
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intermixed with wildlands?
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Affected Environment After completion of construction, this project will have no involvement with hazardous materials. Upper York Creek Dam and Reservoir have two potentially significant sources of naturally-occurring hazardous materials that could result in adverse effects during construction.
The dam is constructed of local rock and soil. The bedrock is a shale/serpentinite mélange, and area soils may have high serpentine content (Corps DPR, 2006). Serpentine has asbestos that could potentially become airborne through construction activities. Asbestos is a carcinogen that can cause lung damage when inhaled. The BAAQMD regulates construction activities in areas with naturally-occurring asbestos under the Asbestos Airborne Toxic Control Measure (ATCM) for Construction, Grading, Quarrying and Surface Mining Operations Law (BAAQMD).
The upper reservoir has a deep layer of sediment. Anaerobic bacteria live in aquatic sediments in ponds, marshes, lakes, streams, and rivers and anywhere that flow rates are low enough to allow sediment to accumulate. These bacteria produce hydrogen sulfide as a by-product of their metabolism. Hydrogen sulfide is a neurotoxin. This is the natural condition of the system and does not pose a hazard. However, when the deep sediments are disturbed, there is potential for hydrogen sulfide to get into the air or water, and, if concentrations are sufficiently high, it could pose a risk to human health and/or have negative effects on aquatic organisms.
Standards Asbestos? Project effects would be considered significant if the airborne level of hydrogen sulfide were to exceed 0.03 ppm (California State Standard, BAAQMD). Standards established in the Initial Study for the York Creek Diversion Modification Project were based on professional judgment as to whether or not the handling of hazardous materials during the project would pose a significant hazard to the public or the environment through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment (DWR, 2002).
Environmental Consequences As stated above, the project may have the potential to generate airborne asbestos and airborne or waterborne hydrogen sulfide. Existing best management practices will be used to prevent impacts from asbestos. It is anticipated that essentially all impacts from
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hydrogen sulfide will be avoided. Overall, project impacts from hazardous materials are expected to be much less than significant. The City of St. Helena will, as part of the permit process, be working out a site-specific avoidance plan to be approved by the BAAQMD. Details will be included in the EIR.
Hydrology and Water Quality
Potentially Less Than Less Than No Would the project: Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Violate any water quality standards or waste X discharge requirements?
b) Substantially deplete groundwater supplies or X interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level?
c) Substantially alter the existing drainage pattern X of the site or area, including through the alteration of the course of a stream or river, in a manner which would result in substantial erosion or siltation on- or off-site?
d) Substantially alter the existing drainage X pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site?
e) Create or contribute runoff water which would X exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff?
f) Otherwise substantially degrade water quality? X
g) Place housing within a 100-year flood hazard X area as mapped on a federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map?
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h) Place within a 100-year flood hazard area X structures which would impede or redirect flood flows? i) Expose people or structures to a significant risk X of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam? j) Inundation by seiche, tsunami, or mudflow? X
Affected Environment
Physical Environment York Creek watershed covers an area of approximately 4.4 acres from the ridge top of the Mayacmas Mountains down the east slope, across the Napa Valley to the Napa River (Jones & Stokes and EDAW, Inc.). Elevation ranges from over 2,200 feet to about 220 feet (USGS, St. Helena Quad). Annual rainfall averages 35 to 40 inches (Corps EA, 2006).
York Creek is a second order stream, which means that it is a perennial headwater stream fed by two tributaries that arise from springs or ephemeral streams. The creek originates at about 2,200 feet and travels 7.24 miles to its confluence with the Napa River. In the upper reaches, it is largely unaltered except for the presence of the upper dam and reservoir. A good combination of pool, riffle and run occur both above and below the dam.
Through the City of St. Helena, York Creek has been modified by the removal of riparian vegetation, bank modification, levees, and roads (Corps EA, 2006). The last approximately 0.4 miles are channelized (USGS). During the New Year’s Storm of 2005- 2006, the creek exceeded channel capacity and flooded a Beringer Winery warehouse parking lot, vineyards, and the Culinary Institute’s dorms (Corps EA, 2006).
Regulatory Environment The City of St. Helena has the only pre-1914 appropriative rights to York Creek. This entitles the City to change the amount or use of water that they remove from the creek without permission from the State Water Resources Control Board. However, they still need permission to change the location of water diversion.
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Standards The San Francisco Bay Regional Water Quality Control Board, through the San Francisco Bay Basin Plan adopted June 21, 1995, and further approved by the State Water Resources Control Board and Office of Administrative Law, as amended through June 14, 2006, sets objectives for acceptable levels of water contamination that still allow for beneficial uses (SFBWQCB, 2006). The project would be considered to have a significant effect if it caused water quality to change so that it no longer meets these objectives as stated in Table 2 below. Criteria were included when measurable quantitative or qualitative standards were included in the objective as stated in the Basin Plan.
Table 2: Water Quality Objectives from the San Francisco Bay Basin Plan for Surface, Cold Water Habitats
Criteria Objective Bacteria Median less than 240 MPN/100 ml total coliform bacteria Biostimulatory Substances will not occur at concentrations that promote Substances aquatic growth enough to cause phytoplankton blooms Dissolved Oxygen Minimum of 7.0 mg/L Oil and Grease Levels less than would create a visible film or coating pH Between 6.5 and 8.5, no change greater than 0.5 Sulfide Not above natural background levels Temperature No increase larger than 5º F No toxics in ambient water at concentrations that produce Toxicity acute toxicity Not over 10% if natural background is over 50 NTU, or at a Turbidity level that would nuisance or adversely affect beneficial uses. Unionized Ammonia Less than 0.16 mg/L as N
Hydrological effects, including changes in flood level or frequency, would be considered significant if they created measurably increased risk to life or property.
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Environmental Consequences The project has no components that would affect bacteria, biostimulatory substances, or unionized ammonia. Adverse effects from oil, grease and/or turbidity could occur from construction equipment working within the bed and bank of York Creek or at the lower reservoir. These impacts will be avoided or minimized by use of best management practices for vehicle maintenance and erosion control in sensitive areas.
Temperature increases could potentially occur if water were detained in the by-pass structure. The dewatering will be designed in consultation with CDFG and NMFS. Aquatic habitat requirements, including temperature, dissolved oxygen, and pH, will be included in the design.
Because hydrogen sulfide builds up naturally in sediments, it would be possible to have increased sulfide levels and accompanying pH changes when sediments are removed. These impacts will be avoided by dewatering sediments before disturbing them, and sulfide levels will be monitored during construction to ensure that they do not rise above normal background levels. Any unacceptable increase in sulfide levels will cause construction to be halted while the water protection measures are adjusted to correct the problem.
Dams usually have the effect of spreading out the time during which a heavy rain makes its way to the floodplain by catching run-off and only releasing a spillway amount at a time. Therefore, they tend to reduce the frequency and depth of downstream flooding events. Removing a dam can, therefore, create increases in frequency and depth of flooding. However, the Upper St. Helena Dam has virtually no storage capacity remaining so it is possible that it is not providing flood alleviation. Additionally, the effect of large, downstream releases of sediment during major storm events has the potential to exacerbate downstream flooding.
The system requires careful fluvial geomorphological study in order to determine the impacts of dam removal, both for direct flooding and for the increased sediment transport that may follow dam removal. This study will be conducted as part of the EIR process. Since the study may determine that dam removal will have positive, negative, or no effect on flooding, until such time as better information is available, impacts must be considered as potentially significant.
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Land Use and Planning
Would the project: Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Physically divide an established community? X
b) Conflict with any applicable land use plan, X policy, or regulation of an agency with jurisdiction over the project (including, but not limited to the general plan, specific plan, local coastal program, or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect?
c) Conflict with any applicable habitat X conservation plan or natural community conservation plan?
Affected Environment The main project site, Upper York Creek Dam and Reservoir, is within the boundaries of Napa County. The area is, however, owned by the City of St. Helena. One of the possible disposal sites, Fulton Lane, is within the boundaries of the City of St. Helena.
Standards Impacts to land use and planning will be considered significant if they conflict with land use designations in the St. Helena General Plan or Napa County land use goals and policies.
Environmental Consequences The dam site has a designation of “Agriculture, Watershed or Open Space Lands” in the Napa County General Plan. Depending on the project alternative selected, some riparian vegetation will be removed at the dam site as part of the alteration or removal. Napa County Open Space Conservation Policy 6(g) for preservation of fishery and wildlife habitat prohibits removal of streamside vegetation Source: Napa County
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General Plan, p. 8-10. The project will result in restoration of the creek channel and revegetation with native riparian species. Thus, the impact will be less than significant with mitigation incorporation.
At the possible Fulton Lane reuse area, the land is designated for agricultural uses in the City of St. Helena General Plan. Should the site be selected for sediment disposition, the impacts on those agricultural uses will not conflict with any existing City of St. Helena policies, leading to a finding of less than significant impact. However, as discussed above in the Agricultural Resources section, this portion of Fulton Lane is classified as prime farmland as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources, and the conversion of prime farmland would require a finding of potentially significant impact on agricultural resources that would require further review in the EIR.
Mineral Resources
Potentially Less Than Less Than No Would the project: Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Result in the loss of availability of a known X mineral resource that would be of value to the region and the residents of the state?
b) Result in the loss of availability of a locally- X important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan?
Not applicable to this project. The project will not create new impermeable areas or otherwise render any existing mineral resources less available than they currently are.
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Noise
Would the project result in: Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Exposure of persons to or generation of noise X levels in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies?
b) Exposure of persons to or generation of X excessive groundborne vibration or groundborne noise levels?
c) A substantial permanent increase in ambient X noise levels in the project vicinity above levels existing without the project?
d) A substantial temporary or periodic increase in X ambient noise levels in the project vicinity above levels existing without the project?
e) For a project located within an airport land use X plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels?
f) For a project within the vicinity of a private X airstrip, would the project expose people residing or working in the project area to excessive noise levels?
Affected Environment The proposed project would occur in a rural area that generally has lower noise levels than in nearby urban areas. The potential disposition sites are located in both rural areas of Napa County and within the boundaries of the City of St. Helena.
In general, Napa County is a quiet place. Typical ambient noise level away from roadways during the day in the northern part of the county is approximately 30 dBA
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and approximately 50 dBA in the southern areas. dBA is decibel as measured on a sound level meter using the A-weighting filter network. Source: Napa County General Plan, p. 11-7.
Standards Within the City of St. Helena, an increase of 5 dBA or greater from the average noise environment is considered subjectively significant. Source: City of St Helena General Plan, p. 8-6. Napa County’s General Plan includes a planning measure requiring noise surveys as part of Environmental Impact Reports for noise-producing projects proposed near sensitive areas. Source: Napa County General Plan, p. 11-33. Sensitive areas include schools, nursing homes, homes for the elderly, and churches.
Environmental Consequences Construction equipment and activities will cause a temporary noise level increase at the project site and any selected disposition sites. Construction equipment usually generates noise levels of 80-90 dBA at a distance of 50 feet while the equipment is operating. Source: U.S. Environmental Protection Agency, 1971.
The project site is located in a steep canyon, and heavy vegetation should provide dampening of the noise levels. Construction will occur during daylight business hours, and, other than residential neighbors, there are no known sensitive receptors such as hotels, schools, nursing homes, homes for the elderly, or churches near the project or potential disposal sites.
There are no residential neighbors immediately adjacent to the project site. There are residential neighbors adjacent to two of the possible dispostion sites, Fulton Lane and the Lower York Creek Reservoir. Residential neighbors living near the possible disposition sites will experience temporarily increased noise levels from trucks delivering sediment during the construction period, which results in a finding of a potentially significant impact.
[Add LS attenuation language?]
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Population and Housing
Would the project: Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation a) Induce substantial population growth in an area, either directly (for example, by proposing new homes and businesses) or indirectly (for example, through extension of roads or other X infrastructure)? b) Displace substantial numbers of existing housing, necessitating the construction of replacement housing elsewhere? X c) Displace substantial numbers of people, necessitating the construction of replacement housing elsewhere? X
Affected Environment In general, this project will have no impact on housing. There is nothing about it that would induce growth. However, some of the spoils may be used alleviate flooding.
Standards Impacts to housing would be considered significant if they conflicted with the General Plan for the City of St. Helena or with Napa County housing goals and policies. Source: existing City of St. Helena standards as stated in Initial Study for the York Creek Diversion Modification Project (DWR, 2002).
Environmental Consequences The project will neither create nor remove housing. If spoils are used in flood control at Fulton Lane, there may be a very small effect on short-term housing or vacation accommodations while the few families involved vacate during construction.
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Public Services
Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Would the project result in substantial adverse physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the public services:
Fire protection? X
Police protection? X
Schools? X
Parks? X
Other public facilities? X
Affected Environment According to the City’s General Plan, public service levels are adequate within the City limits. However, hillside areas on the perimeter of town have a very high potential for wildfires and provide the greatest service challenge due to the combination of highly flammable vegetation, long and dry summers, rugged topography, and the presence of people who live, work, and recreate there (DWR, 2002).
Standards Impacts to public services would be considered significant if they conflicted with the General Plan for the City of St. Helena or with Napa County public services goals and policies. Source: existing City of St. Helena standards as stated in Initial Study for the York Creek Diversion Modification Project (DWR, 2002). Further, impacts would be
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considered significant if they resulted in unacceptable service ratios, response times, or other performance objectives for any of the public services or in substantial adverse physical impacts associated with the need for new or physically altered public facilities, the construction of which could cause significant environmental impacts.
Environmental Consequences Modification and ecosystem restoration of the Upper York Creek Dam and Reservoir will not require construction of new or physically altered public facilities, including emergency services (i.e., fire, police), schools, and parks. In order to insure emergency response times at their current levels, flaggers will be on site to control traffic, and fire and police vehicles will be given priority over construction equipment and vehicles on Spring Mountain Road. Neither currently existing service ratios nor other performance objectives for any public services will be impacted.
The Corps has identified the potential for an adverse impact from the “no project” alternative. Namely, emergency services could be adversely affected by collapse of Spring Mountain Road. The preferred alternative, 2B (Corps DPR, 2006), addresses this potential by providing the most geologically stable configuration through retention and filling of the existing spillway along Spring Mountain Road.
Project activities will include the use of construction equipment and trucks for hauling. All vehicles and equipment associated with the project will be inspected for safety by the project engineer, and emergency fire and hazardous substances clean up gear will be on site at all times. A pre-construction safety meeting will be held.
At this time, no other projects that may affect public services are currently proposed in the project areas along Spring Mountain Road (SCH, 2006). No adverse cumulative impacts associated with the provision of public services from the ecosystem restoration project are anticipated.
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Recreation
Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation a) Would the project increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur X or be accelerated? b) Does the project include recreational facilities or require the construction or expansion of recreational facilities which might have an adverse physical effect on the environment? X
Affected Environment The park system in the City of St. Helena consists of seven parks totaling approximately 32.3 acres (Carrick, 2006). The City has a low ratio of active parklands to population (DWR, 2002), and Napa County does not have a county park system. Approximately 40,000 acres of open space lands exist in the county that are managed by the Bureau of Reclamation, California Department of Fish and Game, and the county water district, but these lands are not currently accessible to the public. A measure to provide for a county park system is on the ballot for the November 2006 election (Carrick, 2006).
The upper York Creek dam and reservoir provide little opportunity for recreation. Hiking and recreational uses of York Creek are discouraged by the City (Carrick, 2006). The lower reservoir is accessible to hikers.
While not designated as scenic, Spring Mountain Road is a beautiful rural road that is very popular for bicycling. In addition, there are approximately 24 small wineries along the road. These vineyards, which comprise the Spring Mountain area, known for high- quality, mountain-grown cabernets, are a tourist destination.
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Standards Impacts to recreation would be considered significant if the project resulted in an increase in the use of existing parks or other recreational facilities such that substantial physical deterioration would occur or be accelerated. Further, impacts would be considered significant if the project resulted in the need for construction or expansion of recreational facilities that might have an adverse physical effect on the environment. Source: existing City of St. Helena standards as stated in Initial Study for the York Creek Diversion Modification Project (DWR, 2002).
Environmental Consequences While the purposes of the project are prevention of potential sediment releases and flooding and ecosystem restoration, the project will result in improved riparian and aquatic habitat that may allow for future passive recreational opportunities, such as bird watching. The Corps identified potential recreational benefits to sport fishing from improved steelhead migration (Corps EA, 2006). No other projects that may affect parks or other recreational facilities are proposed (SCH, 2006).
Minor, short-term impacts to bicycling and tourist travel along Spring Mountain Road will occur during project activities. Along with emergency vehicles, bicyclists will be given special consideration by flaggers and construction vehicles. Avoidance of impacts to bicyclists will be included in the pre-construction training, and warning signs indicating road conditions will be posted to alert bicyclists to potential hazards along the construction routes.
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Transportation and Traffic
Potentially Less Than Less Than No Would the project: Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Cause an increase in traffic which is substantial in relation to the existing traffic load and capacity of the street system (i.e., result in a substantial increase in either the number of vehicle trips, the X volume to capacity ratio on roads, or congestion at intersections)?
b) Exceed, either individually or cumulatively, a level of service standard established by the county congestion management agency for designated roads or highways? X
c) Result in a change in air traffic patterns, including either an increase in traffic levels or a change in location that results in substantial safety risks? X
d) Substantially increase hazards due to a design feature (e.g., sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment)? X
e) Result in inadequate emergency access? X
f) Result in inadequate parking capacity? X
g) Conflict with adopted policies, plans, or X programs supporting alternative transportation (e.g., bus turnouts, bicycle racks)?
Affected Environment Access to the Upper York Creek Dam and Reservoir will be off of Spring Mountain Road, which is a narrow, 2-lane, curvy road that connects St. Helena and Santa Rosa.
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There are approximately two dozen wineries along the road but little other development. The road gets both car and bicycle through traffic and tourist traffic to the wineries. At the lower end, Spring Mountain Road becomes a city street in St. Helena. At that point, truck traffic would need to turn left on Elmhurst for one block, and then left on Main Street/ Highway 128. The intersection of Elmhurst and Main is signaled.
Standards Traffic impacts would be considered significant if they decrease an existing Level of Service (LOS). The LOS for a road or intersection is a measurement that includes speed and travel time, traffic interruptions, freedom to maneuver, safety, driving comfort and convenience, and operating costs. LOS A represents virtually free-flow conditions, with unrestricted ability to maneuver in the traffic stream. Levels B, C, and D represent increasing levels of flow rate with correspondingly more interference from other vehicles in the traffic stream.
Environmental Consequences This project will have no long-term impacts to traffic. All impacts will be temporary, short-term construction activities. Project impacts may result from two sources: construction site access at Upper York Creek Reservoir and an increase in total traffic caused by trucks moving spoils to reuse and disposal sites. Both will be affected by the project alternative selected because that will determine the amount of material to be relocated and the duration of construction.
During the period when spoils are being moved to a disposition site, trucks would be utilizing rural arterial and collector roads. Some of the trucks, those going to Clover Flat landfill or taking spoils for flood control use, would need to travel through the City of St. Helena. This could potentially negatively impact the level of service at intersections in the City, which will be further evaluated and appropriate mitigation developed during the EIR process.
The other potentially significant impact is to Spring Mountain Road traffic, which will need to be traffic controlled at the reservoir(s) to allow trucks to enter and leave the construction site. The amount of potential delay and methods for ensuring no decrease in emergency access will also be included in the EIR.
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There is no plan to change Spring Mountain Road itself, and, therefore, the project will not conflict with adopted policies, plans, or programs supporting alternative transportation.
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Utilities and Service Systems
Potentially Less Than Less Than No Would the project: Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Exceed wastewater treatment requirements of the applicable Regional Water Quality Control Board? X
b) Require or result in the construction of new water or wastewater treatment facilities or expansion of existing facilities, the construction of which could cause significant environmental X effects?
c) Require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? X
d) Have sufficient water supplies available to serve the project from existing entitlements and resources, or are new or expanded entitlements needed? X
e) Result in a determination by the wastewater treatment provider which serves or may serve the project that it has adequate capacity to serve the project=s projected demand in addition to the X provider=s existing commitments?
f) Be served by a landfill with sufficient permitted X capacity to accommodate the project=s solid waste disposal needs?
g) Comply with federal, state, and local statutes X and regulations related to solid waste?
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Affected Environment The project will not produce wastewater or have any impact on wastewater treatment facilities. If needed, water may be taken from York Creek under the City of St. Helena’s existing appropriative water rights. The project will be performed in accordance with applicable solid waste regulations.
Standards Impacts to utilities and service systems would be considered significant if they conflicted with the General Plan for the City or with Napa County goals and policies. Source: existing City of St. Helena standards as stated in Initial Study for the York Creek Diversion Modification Project (DWR, 2002).
Environmental Consequences In general, this project does not impact public services. If spoils are taken to Clover Flat landfill, they will not exceed the permitted capacity. Any spoils above that capacity will be placed elsewhere.
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Mandatory Findings of Significance
Potentially Less Than Less Than No Significant Significant Significant Impact Impact with Impact Mitigation Incorporation
a) Does the project have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below X self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of a rare or endangered plant or animal or eliminate important examples of the major periods of California history or prehistory?
b) Does the project have impacts that are individually limited, but cumulatively considerable? ("Cumulatively considerable" means that the incremental effects of a project are X considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects)?
c) Does the project have environmental effects X which will cause substantial adverse effects on human beings, either directly or indirectly?
A historic resources evaluation was prepared by Bright Eastman, Anthropological Studies Center at Sonoma State University, in 2003, which concluded that the Upper St. Helena Dam appears eligible for the National Register of Historic Places under Criterion A, at a local level of significance in the area of community planning and development, and for the California Register of Historical Resources pursuant to California Public Resources Code §5024.1(d)(1). With a period of significance of 1900, the dam and reservoir are important features of infrastructure for the City of St. Helena in the early 20th century. This water collection and conveyance facility was essential for the growth and development of the town in the early 20th century because it extended the city’s water storage and distribution system, making more water service available to new commercial and residential properties that were being built, in addition to assuring more water was available for fire protection (Eastman, 2003). The proposed project would have a significant impact on the dam and spillway. CEQA Guidelines specify
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that a substantial adverse change in the significance of an historical resource is a significant effect requiring preparation of an EIR. The alteration of an historical resource, as proposed by the project, is considered a substantial adverse change and, therefore, a significant effect (Guidelines §15064.5).
Potentially significant impacts for review during the EIR process have been identified in the areas of agriculture, biological resources, cultural resources (discussed above), geology and soils, hazards and hazardous materials, hydrology and water quality, and transportation and traffic. At this time, no cumulatively considerable impacts have been identified. However, further study and evaluation of potential cumulative effects will occur.
No substantial adverse effects on human beings, either directly or indirectly, are anticipated from project implementation. However, further study and evaluation of potential impacts on human beings will occur during the EIR process. Areas of particular emphasis will include geology and soils (landslides, liquifaction), hazardous materials (asbestos, hydrogen sulfide), hydrology and water quality (flooding, sedimentation), and transportation and traffic (changes in levels of service).
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References
Air Resources Board. http://www.arb.ca.gov.
Air Resources Board. Rulemaking informal: 2002-09 methodologies.
Association of Bay Area Governments (ABAG ). ABAG Earthquake Maps and Information. http://quake.abag.ca.gov/.
Bay Area Air Quality Management District. 1999. BAAQMD CEQA Guidelines: Assessing the Air Quality Impacts of Projects and Plans. Bay Area Air Quality Management District, Planning and Research Division. December 1999.
California Department of Water Resources (DWR). 2002. Initial Study for the York Creek Diversion Modification Project, Napa County, California. Prepared for the City of St. Helena. November 2002.
Carrick, Kathy. 2006. Director of Parks and Recreation, City of St. Helena. Personal communication, September 15 and 19, 2006.
City of St. Helena. 1993. General Plan Policy Document. September 1993.
City of St. Helena. 2004. Final Environmental Impact Report for the City of St. Helena York Creek Diversion Modification Project. City of St. Helena, Department of Public Works. January 2004.
City of St. Helena. 2003 Initial Study/Mitigated Negative Declaration, Project: Fulton Lane Storm Drain. Prepared for the City of St. Helena, March 2003.
Eastman, B. 2003. Historical Resources Evaluation Report for the Proposed Removal of an Earthen Dam and Diversion Structure on York Creek near the City of St. Helena in Napa County, California. Prepared for the City of St. Helena by Bright Eastman, Anthropological Studies Center, Sonoma State University, Rohnert Park, California.
Innovative Technical Solutions, Inc. 2003. HTW Assessment, Upper York Creek Ecosystem Restoration Project, St. Helena, California. U.S. Army Corps of Engineers, San Francisco District. December 2003.
City of St. Helena Page 54
Upper York Creek Ecosystem Restoration Administrative Draft Initial Study Checklist
Jones & Stokes and EDAW, Inc. 2005. Napa County Baseline Data Report, Version 1 – November 30, 2005. Napa County Conservation, Developmetn and Planning Department.
Leidy, R.A., G.S. Becker, and B.N. Harvey. 2005. Historical distribution and current status of steelhead/rainbow trout (Oncorhynchus mykiss) in streams of the San Francisco Estuary, California. Center for Ecosystem Management and Restoration, Oakland, CA.
Napa County. 2002. Napa County General Plan. Amended through March 5, 2002.
Prunuske Chatham, Inc. 2006a. California Red-legged Frog (Rana aurora draytonii) Site Assessment, York Creek Sediment Removal Project, City of St. Helena. May 2006.
Prunuske Chatham, Inc. 2006b. City of St. Helena York Creek Dam Sediment Removal Project, La Perla 70, Site Biological Impacts Evaluation. June 2006.
Prunuske Chatham, Inc. 2006c City of St. Helena York Creek Dam Sediment Removal Project, Lower York Creek Reservoir Site, Biological Impacts Evaluation. June 2006.
Prunuske Chatham, Inc. 2006d. City of St. Helena York Creek Dam Sediment Removal Project, Spring Mountain Vineyard Olive Orchard Site, Biological Impacts Evaluation. June 2006.
San Francisco Bay Regional Water Quality Control Board. 2005 San Francisco Bay Basin Plan, with amendments through June 14, 2006. http://www.swrcb.ca.gov/rwqcb2/basinplan/web/BP_TOC1.html
State Clearinghouse (SCH). 2006. CEQAnet. http://www.ceqanet.ca.gov.
State Water Resources Control Board. San Francisco Bay Basin Plan. 2005 with amendments through July 2006. http://www.swrcb.ca.gov/rwqcb2/basinplan/web/BP_TOC1.html
U.S. Army Corps of Engineers (Corps DPR, 2006). Draft Detailed Project Report: Upper York Creek Ecosystem Restoration Project, Napa County, California. U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006
City of St. Helena Page 55
Upper York Creek Ecosystem Restoration Administrative Draft Initial Study Checklist
U.S. Army Corps of Engineers (Corps EA, 2006). Draft Environmental Assessment: Upper York Creek Ecosystem Restoration Project, Napa County, California. U.S. Army Corps of Engineers, San Francisco District, South Pacific Division. September 2006.
US Geological Survey. 1980. Calistoga 7.5’ Quadrangle. 1:24,000. USGS. Reston, Virginia.
US Geological Survey. 1980. St. Helena 7.5’ Quadrangle. 1:24,000. USGS. Reston, Virginia.
Watershed Information Center and Conservancy. http://www.napawatersheds.org/cgi-bin/maps.php.
City of St. Helena Page 56
Appendix 2
Lower York Creek Reservoir Revegetation and Mitigation Plan
Lower York Creek Reservoir Revegetation and Mitigation Plan
Introduction and Objectives Fill (sediments and other soils) is to be placed at the Lower York Creek Reservoir that will impact some upland and wetland vegetation along its shoreline. The fill is from the decommissioning of the Upper St. Helena Dam and Reservoir, which will allow for fish passage and increased habitat available for steelhead in York Creek. The objectives of this plan are to minimize aesthetic impacts by revegetating disturbed areas with appropriate native species and stabilizing surface soils (erosion control).
Responsibility/Ownership It is the responsibility of the owner, the City of St. Helena, to ensure that the following revegetation and mitigation actions are applied to meet the objectives and stated success criteria by employing licensed and/or certified professionals with experience in native revegetation, wildlife habitat restoration, and erosion control.
Impact Minimization/Avoidance Vegetation to be protected shall be demarcated in the field with orange safety fence to prevent unauthorized equipment traffic that could result in soil compaction or other damage to plants. Where it is necessary for equipment to operate within the dripline of trees, a tree protection protocol shall be implemented: the tree trunks shall be protected with a wrap of heavy rubber or similar material, and the ground shall be covered with a thick layer of wood chips or trench plates (as determined by a certified arborist or landscape architect). The Grading Plan will detail how soil is to be placed. The Grading Plan will be produced once a project is approved. The following Revegetation Plan details how plants are to be established and surface soils are to be stabilized.
Revegetation Plan Wetland revegetation: 400’ to 411’ elevation Prior to placement of fill, plants within the fill area that are listed as “transplant” in Table 1 shall be excavated and stored until the site is ready to receive plantings. The plants shall be stored in shaded transplant beds with sufficient irrigation to ensure their survival. In addition, a thin layer of topsoil
Lower York Creek Reservoir Revegetation and Mitigation Plan January 2007 Prunuske Chatham, Inc. Page 2 of 5
(approximately two inches in depth) shall be stripped from the fill area and stockpiled.
Once the fill has been placed and graded, the stockpiled topsoil shall be spread over the wetland area. A seed mix composed of 70% meadow barley, 10% spikerush, 10% iris-leaved rush, and 10% California bulrush shall be spread over the site at a rate of 40 pounds per acre. Rice straw or wood fiber hydromulch will then spread at a rate of 3,000 pounds per acre over the site and tackified with organic tackifier at a rate of 150 pounds per acre. Seeding and mulching shall occur prior to October 15.
A mix of transplants (from Table 1 below) will then installed in species clusters with an average spacing of two feet by two feet (4 sq. ft. per plant). Clusters shall cover approximately 50% of the fill area below the 411-foot elevation. Transplanting shall occur between November 1 and January 31 or whenever the soil moisture is close to holding capacity.
A mix of woody sprigs (from Table 1) shall be installed near the 410-foot to 412- foot elevation (see planting detail). Species shall be grouped in clusters. Within clusters, sprigs shall be approximately 12 feet on center. These woody sprig clusters shall be installed on approximately 50% of the shoreline.
Table 1. Wetland Species List – Elevations 400’ to 411’
Species Common Name Seed Transplant Sprig Propagules: Eleocharis macrostachya spikerush x x Hordeum brachyantherum meadow barley x Juncus xiphioides iris-leaved rush x x Scirpus californicus Calif. Bulrush x x
Woody species: Salix exigua narrow-leaved willow x Populus fremontii Fremont cottonwood x
Upland revegetation: above elevation 411’ Prior to the placement of fill, a thin layer of topsoil (approximately two inches deep) shall be stripped from the fill area and stockpiled. Once the fill has been placed and graded, the stockpiled topsoil shall be spread over the upland area. A seed mix composed of 70% blue wildrye, 20% purple needlegrass, 5% California poppy, and 5% blue-eyed grass shall be broadcast site at a rate of 50 pounds per acre. A mycorrhizal inoculant (AM120 or equal) shall be mixed with the seed at a Appendix 2 Lower York Creek Reservoir Revegetation and Mitigation Plan January 2007 Prunuske Chatham, Inc. Page 3 of 5
rate of 60 pounds per acre. Rice straw or wood fiber hydromulch is then spread at a rate of 3,000 pounds per acre over the site and tackified with organic tackifier at a rate of 150 pounds per acre. Seeding and mulching shall occur prior to October 15.
Between October 15 and January 31, a mix of container plants listed in Table 2 shall be installed in clusters of 3 to 7 plants of similar species per cluster (see planting detail). Total number of container plants shall be approximately 200 per acre (8 to 16-foot spacing between plants).
Table 2. Upland Species List – above Elevation 411’
Species Common Name Seed Container Propagules: Elymus glaucus blue wildrye x Eschscholzia californica Calif. Poppy x Nassella pulchra purple needlegrass x Sisyrinchium bellum blue-eyed grass x
Woody species: Aesculus californica buckeye x Arctostaphylos manzanita manzanita x Baccharis pilularis coyote brush x Heteromeles arbutifolia toyon x Quercus agrifolia coast live oak x Quercus douglasii blue oak x Quercus kelloggii black oak x Quercus lobata valley oak x
Maintenance/Establishment Wetland Plantings: The typical establishment period for wetland plantings is one year. Maintenance may be discontinued at that time if success criteria are met (see Success Criteria and Contingencies/Remedial Action below). Elements of maintenance are as follows: • Irrigation of wetland areas will be dependent upon the reservoir’s water levels. Bi-weekly watering with impact sprinklers or mini-misters may be required should reservoir levels drop early in the summer. The revegetation specialist in charge will make the determination at the time. • Weeding of exotic and/or invasive species shall be performed by hand (non-chemical) as needed to minimize non-native plant competition with the native species.
Appendix 2 Lower York Creek Reservoir Revegetation and Mitigation Plan January 2007 Prunuske Chatham, Inc. Page 4 of 5
• Browse protection shall be implemented if significant browse damage is observed by the revegetation specialist. Browse protection may consist of individual plant protectors, netting, or organic-based repellant sprays.
Upland Plantings: The typical establishment period for upland plantings is three years. Maintenance may be discontinued at that time if success criteria are met (see Success Criteria and Contingencies/Remedial Action below). Elements of maintenance are as follows: • Irrigation of individual plants shall be achieved by either weekly watering via drip irrigation (one gallon per plant, twice each week) or the use of irrigation gel packs (two per plant, replenished approximately 3 times per year). The revegetation specialist in charge will make adjustments in the watering regime as needed depending on weather and plant conditions. • Weeding of exotic and/or invasive species shall be performed by hand (non-chemical) as needed to minimize non-native plant competition with the native species. At a minimum, an area 1.5 feet in radius shall be kept weed-free around each plant. • Browse protection shall be implemented if significant browse damage is observed by the revegetation specialist. Browse protection may consist of netting or organic-based repellant sprays.
Monitoring /Reporting Bi-monthly monitoring is required. The revegetation specialist or representative thereof shall inspect plantings twice per month to determine reservoir level, soil moisture levels, watering requirements, condition of irrigation system, as well as weeding and browse protection requirements. This information will be recorded, and any necessary remedial tasks will be assigned to responsible personnel.
Annual monitoring shall be performed in September or October to determine the survival rates, conformance to success criteria, and remedial action required. The annual monitoring report shall be submitted to the City and permitting agencies at their request.
Winter monitoring from November to the end of February will focus on erosion control needs.
Success Criteria and Contingencies/Remedial Action Wetland Plantings: Wetland plantings shall be considered successful if, at the end of one year, the cover of wetland species is equal to 70% of the cover of nearby equivalent reference wetlands. If the cover falls below 70% at the end of one year, the revegetation specialist shall determine if additional planting is required or if an additional growing season for existing plants will allow growth
Appendix 2 Lower York Creek Reservoir Revegetation and Mitigation Plan January 2007 Prunuske Chatham, Inc. Page 5 of 5
to meet cover criteria. If after two years the cover criteria is not met, additional plantings will be required until the area has 70% of the reference cover established for one year or more.
Upland Plantings: Upland plantings shall be considered successful if 80% of the number of woody plants installed are alive and healthy and have been in the ground for three years. Native species that have seeded in naturally may be counted towards achieving this goal. Replacement planting shall be required until these criteria are met. A total native plant cover of 50% may be used as an alternative measure of success.
Surface Erosion Control: Erosion control shall be considered successful as long as the measures specified in the Grading Plan are effective, significant seed germination is observed, and the mulch remains intact. Where rills, gullies, or other signs of erosion are observed, additional seed, mulch, wattles, or other BMPs shall be deployed as determined by the erosion control specialist.
Schedule Summary
Pre-grading, Collect or purchase seed spring/summer Contract with nurseries to provide plants Install plant protection fencing and tree protection Excavate and store wetland plant materials Excavate and store topsoil
October Replace topsoil Seed and mulch by October 15
November 1 to January 31 Install container plants, transplants, and sprigs Repair erosion control as needed
April 1 to November 1 Maintain plants and monitor (3 years minimum) September/October Annual survival and cover monitoring & report November 1 to January 31 Replacement planting as needed November 1 to March 31 Monitor and maintain or replace erosion control measures
Appendix 2 D R A F T July 2004
GROUND SURFACE 2 INCH HIGH 3/4 INCH TO BERM 1-1/2 INCH DIA. WILLOW SPRIG 1 FT. GROUND SURFACE 1 FT.
12 INCH WIDE WATER BASIN ON SLOPES 2 FT. 2 FT.
INSTALLATION ON HILL SLOPE INSTALLATION ON FLAT GROUND WILLOW OR COTTONWOOD SPRIG PLANTING DETAIL
SECURE SEEDLING PROTECTOR INSTALL 36 INCH TALL, WITH TWO 4 FT. TALL BAMBOO 4 INCH ± DIA. RIGID DIAMOND STAKES WOVEN THROUGH MESH MESH PLASTIC SEEDLING PROTECTOR 1 INCH INTO GROUND 12 INCH DIAMETER WATERING BASIN
INSTALL PLANT WITH ROOT CROWN AT OR 1 INCH MAX. ABOVE GRADE
2 - 4 INCH COMPACTED BERM ON DOWNHILL SIDE OF PLANT
36 INCH x 36 INCH WEED CONTROL FABRIC DIG PLANTING HOLE TO SAME DEPTH AS ROOT MASS AND AT LEAST TWICE AS WIDE GRADE
PLACE 1 MYCORRHIZAE PACKET 1/2 WAY UP PLANTING HOLE. COVER WITH SOIL. FIRM IN NATIVE ANCHOR WITH 50d NAIL AND BACKFILL AROUND ROOTBALL TO WASHER OR 6 INCH STAPLE AT GRADE CENTER AND EACH CORNER
NOTE: SEEDLING PROTECTORS TO BE PLACED ON TREES ONLY. SHRUBS AND VINES TO BE PLANTED AS ABOVE WITHOUT SEEDLING PROTECTOR. REMOVE PROTECTOR AFTER 3 YEARS. CONTAINER - GROWN PLANTS PLANTING DETAIL Source: ©Prunuske Chatham, Inc. Occidental, CA
FishNet Guidelines Appendix A-BMP Toolbox
Appendix 3
Notice of Preparation of a Draft Environmental Impact Report, Upper York Creek Restoration Project
NOTICE OF PREPARATION OF A DRAFT ENVIRONMENTAL IMPACT REPORT UPPER YORK CREEK ECOSYSTEM RESTORATION PROJECT
To: Interested Agencies, Parties, Organizations and Persons
From: City of St. Helena 1480 Main Street St. Helena, CA 94574
Subject: Notice of Preparation (NOP) of a Draft Environmental Impact Report (DEIR)
PROPOSED PROJECT The City of St. Helena (City), together with the U.S. Army Corps of Engineers (Corps), is proposing to modify or remove Upper York Creek Dam for the purpose of preventing potentially detrimental sediment releases. The project will also allow fish passage to two upstream miles of spawning and rearing habitat for steelhead and restore approximately three acres of riparian and aquatic habitat. Additionally, the project will provide a long-term solution to prevent dam breach/failure and consequent catastrophic downstream flooding and debris flow.
The City of St. Helena is the lead agency under the California Environmental Quality Act (CEQA) and will be preparing an environmental impact report (EIR) for the project. The City is requesting your input as to the scope and content of the environmental information to be evaluated in the DEIR. Responsible and trustee agencies, interested parties, organizations, and persons are invited to participate in the NOP consultation and the CEQA review process.
OTHER AGENCIES WITH REGULATORY AUTHORITY
NEPA Review The U.S. Army Corps of Engineers is the lead agency under the National Environmental Policy Act (NEPA).
CEQA Responsible and Trustee Agencies Bay Area Air Quality Management District California Department of Fish and Game San Francisco Bay Regional Water Quality Control Board NOAA National Marine Fisheries Service United States Fish and Wildlife Service
Agencies with Jurisdiction by Law Napa County
Other Commenting Agencies Caltrans Napa County Resource Conservation District Notice of Preparation of a Draft Environmental Impact Report Upper York Creek Ecosystem Restoration Project Page 2 of 5
PROJECT LOCATION The proposed project will take place at upper York Creek dam and reservoir (see attached location map). The reservoir is located at 38º 30’ 48” N, 122º 30’ 9” W, in the SW , Section 26, Range 6 West, Township 8 North, Mt. Diablo Base and Meridian of the St. Helena Quadrangle, St. Helena, Napa County, California (USGS). Sediment removed from the dam will be placed at one or more locations in or near the City of St. Helena (see description of proposed action below for details).
CURRENT CONDITIONS
York Creek York Creek runs approximately 7.24 miles (Corps EA) from its headwaters to its confluence with the Napa River. It descends steeply over the first portion of its range then flattens out as it crosses the floodplain of the Napa River. York Creek drains a watershed of approximately 4.4 square miles (Watershed Information and Conservancy Center of Napa County).
At the site of the upper York Creek reservoir, the creek traverses a steep valley cut from serpentinite and sheared shale (Corps). The area is a mixture of hardwood/conifer forests and vineyards. Other land uses include open space and residential.
According to the Napa County Resource Conservation District, York Creek is one of the most significant spawning and rearing streams in the Napa River watershed for Central California Coast ESU steelhead, which are listed as threatened under the federal Endangered Species Act. The Napa River watershed is one of the most significant anadromous fish streams tributary to the San Francisco Bay.
The Upper Dam The current dam was constructed in 1900 to expand water capacity for the City of St. Helena and the growing wine industry. The structure, part of the city’s original water system, has remained essentially unaltered since construction. The earthen dam is 50 feet high, 140 feet long, and is composed of more than 12,000 cubic yards of material excavated to form the upper reservoir. Both faces are protected with basaltic rip rap. It has a drop inlet pipe that leads through the base of the dam.
In 1922, the City of St. Helena purchased this property and the rest of the water delivery system from the St. Helena Water Company. In 1933, a concrete spillway was added adjacent to Spring Mountain Road. Both the dam and the spillway are considered historic properties (Anthropological Studies Center).
The Upper Reservoir The upper reservoir originally had a capacity of 10,000,000 gallons and was used as a water source for the City of St. Helena. Over time, it has accumulated gravel Notice of Preparation of a Draft Environmental Impact Report Upper York Creek Ecosystem Restoration Project Page 3 of 5
and other sediments. By 1993, too much sediment had accumulated to continue to use it as a water source, and now it has essentially no water retaining capacity. There is an estimated 26,000 cubic yards of sediment accumulated behind the dam. There have been four incidents of accidental, catastrophic release of sediment resulting in mortality of fish and other aquatic organisms as far as 2.5 miles downstream.
PROPOSED ACTION The proposed removal or alteration of Upper York Creek Dam is a joint project of the City of St. Helena and the Corps. All of the action alternatives include riparian and riverine habitat restoration of the area disturbed by the original creation of the dam and reservoir. All of the action alternatives except creation of a fish ladder will include restoration of the natural hydrologic processes of York Creek, including moving sediment downstream in a routine way.
Based upon a feasibility analysis by the Corps, there are currently four alternatives being considered:
• No Project – The dam would remain unaltered. No habitat restoration would occur. The City of St. Helena would need to continue maintenance dredging to avoid destructive sediment release. • Total removal of the dam – This alternative would allow creation of a 30- foot wide floodplain bench. It would require stabilization of the hillsides. 100% of the sediment currently accumulated behind the dam would be removed. • Creating a small notch in the dam – This alternative allows restoration of the natural hydrologic functions of York Creek but without a floodplain bench. 95% of the sediment accumulated behind the dam would be removed. It is the most geologically stable alternative that allows restoration of York Creek’s hydrology. • Constructing a fish ladder through the dam – This alternative would create a concrete step-pool/weir fish ladder cut into the dam. 37% of the sediment accumulated behind the dam would be removed. The fish ladder would require on-going maintenance to prevent it from becoming clogged with sediment.
The City will determine the re-use and/or disposal of materials removed from the dam and reservoir according to the project alternative selected and, therefore, the amount of material to be placed. The material will be placed in some combination of the following locations:
• Use at a nearby private vineyard. • Use in a City of St. Helena flood control project. • Use in other City of St. Helena project(s). • Storage in the Lower York Creek Reservoir. • Disposal at an approved facility. . Notice of Preparation of a Draft Environmental Impact Report Upper York Creek Ecosystem Restoration Project Page 4 of 5
ENVIRONMENTAL ISSUES TO BE ANALYZED IN THE EIR The City of St. Helena has determined that an EIR is necessary for this project and identified areas of particular concern based on an initial study and previous environmental documents, including the York Creek Diversion Structure Modification EIR, the Corps’ Draft Upper York Creek Ecosystem Restoration Detailed Project Report, and the Corps’ Draft Upper York Creek Ecosystem Restoration Environmental Assessment. The initial study ( __ is _X is not) attached.
Issues that have been identified for investigation in the EIR are:
• Aesthetics – temporary impacts from construction. • Agriculture – possible loss of some productive land if dam and sediment materials are used for flood control. • Air Quality – temporary impacts from construction. • Biological Resources – the area may contain sensitive and listed species. • Cultural Resources – the dam has been identified as a historical resource of local importance because of its connection with the development of the City of St. Helena and viticulture in the Napa Valley. • Geology – due to presence of serpentine and sheared shale that are prone to instability. • Hazards and Hazardous Materials – the dam was made from local soil and bedrock that may contain naturally-occurring asbestos in the mineral serpentine. • Hydrology and Water Quality – along with preparation of the EIR, thorough hydrologic and geomorphic studies of York Creek will be performed to assess potential impacts with and without the project, particularly in relation to flooding in the lower regions of York Creek through the City of St. Helena. The EIR will address sediment delivery to the Napa River. • Noise – temporary impacts from construction. • Traffic and Transportation – temporary impacts during construction.
The project is not anticipated to have significant impacts to land use, mineral resources, public services, recreation, or utilities.
PUBLIC INFORMATION AND COMMENTS
Documents for Review The following documents provide information about the proposed project and/or the project area:
“If York Creek Could Speak” http://city.ci.st- helena.ca.us/tmspublisher/images/aad/YorkCreek/YorkCreek.html
Initial Study for the York Creek Diversion Modification Project, Napa County, California Notice of Preparation of a Draft Environmental Impact Report Upper York Creek Ecosystem Restoration Project Page 5 of 5
http://www.watershedrestoration.water.ca.gov/fishpassage/docs/york_ initial_diversion%20structure_Jan%202003.pdf
Additionally, concurrent with this notice, the Corps is circulating a draft detailed project report and draft environmental assessment, which can be reviewed at:
St. Helena Public Library 1492 Library Lane St. Helena, CA 94574
Public Meeting The Corps and City of St. Helena will host a public meeting on Thursday, September 21, 2006, 6:00 to 8:00 pm, at:
St. Helena Public Library 1492 Library Lane St. Helena, CA 94574
The purpose of the meeting is to give the public further information about the project and allow the public to raise any issues or concerns with either agency.
Comments Due to the time limits mandated by State law, your response must be sent at the earliest possible date but not later than 30 days after receipt of this notice.
Comments to City of St. Helena regarding the scope of the EIR and environmental issues to be considered should be sent to:
Jonathon Goldman, Director of Public Works and City Engineer City of St. Helena [email protected] 1480 Main Street St. Helena, CA 94574
Comments regarding the NEPA review should be sent to:
Joél Benegar, Project Planner U.S. Army Corps of Engineers San Francisco District [email protected] 333 Market Street San Francisco, CA 94105-2197
Appendix 4
Wetland Delineation for Lower York Creek Reservoir
Artwork by Susan Holve
PRELIMINARY DELINEATION OF WETLANDS AND OTHER WATERS OF THE U.S. LOWER YORK CREEK RESERVOIR SPRING MOUNTAIN ROAD CITY OF ST. HELENA, NAPA COUNTY
PREPARED FOR: CITY OF ST. HELENA 1480 Main Street St. Helena, CA 94574
MARCH 2007
PRELIMINARY DELINEATION OF WETLANDS AND OTHER WATERS OF THE U.S. LOWER YORK CREEK RESERVOIR SPRING MOUNTAIN ROAD CITY OF ST. HELENA, NAPA COUNTY MARCH 2007
PROJECT DESCRIPTION The Study Area is located at the Lower York Creek Reservoir (LYCR), Spring Mountain Road, City of St. Helena, Napa County (Figure 1, Photos 1 to 4). The LYCR is a large freshwater reservoir owned by the City of St. Helena (City) with a current storage capacity of approximately 160 acre-feet. It provides untreated water for a portion of the City’s agricultural irrigation and construction water demands. The Study Area is under consideration for reuse or disposal of materials removed from the Upper York Creek Ecosystem Restoration Project, a fish passage improvement project approximately 0.5 miles upstream of the reservoir along York Creek. The City has retained Prunuske Chatham, Inc. (PCI) to complete a preliminary delineation of jurisdictional wetlands and other waters of the U.S. on the Study Area with assistance from Coast Range Biological, LLC.
METHODOLOGY A routine-level wetland delineation of the Study Area was conducted on December 22, 2006. The purpose of the survey was to delineate all potential jurisdictional wetlands1 and other waters of the U.S.2 The delineation followed protocols described in the Corps of Engineers’ (Corps) Wetland Delineation Manual (Environmental Laboratory 1987). Wetlands are identified using three diagnostic environmental characteristics: hydrophytic vegetation, hydric soils, and wetland hydrology. Under normal circumstances and in unproblematic areas, jurisdictional wetlands exhibit all three diagnostic features.
Prior to the field investigation, a current aerial photograph, the soil survey for Napa County (NRCS 1978), and USGS topographic maps were reviewed. Twelve delineation plots were taken in the field and mapped (Table 1; Figure 2; Appendix B, Routine Wetland Determination Data Forms). Plant species identified within the Study Area were assigned a wetland indicator status3 based on the National List of Plant Species that Occur in Wetlands, Region 10 –
1 See Wetlands in Appendix A. 2 See Waters of the U.S. in Appendix A. 3 See Wetland Indicator Abbreviations in Appendix A.
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 2 of 9
California (RMG 1993). Sample points and potential wetlands were mapped in the field using a Trimble GPS unit with sub-meter accuracy and subsequently overlain on a color digital orthophotograph using AutoCad software. Table 1, Delineation Plots and Determinations, provides a summary of the diagnostic features present for each sample point and preliminary determinations.
This report is a preliminary determination of wetlands and other waters of the U.S. on the Study Area. This determination is not considered complete until the Corps makes an independent assessment of the property and certifies the delineation.
STUDY AREA DESCRIPTION The Study Area is located east of the City of St. Helena in northern Napa County. The site is a large, off-channel, freshwater reservoir surrounded by foothill pine- oak woodland, freshwater wetland, non-native grassland, and ruderal habitats. It is located on the St. Helena USGS quadrangle [T8N and R6W; 38º30’30”N and 122 º29’25”W, NAD83] in the York Creek watershed, a tributary to the Napa River at 420 feet elevation. The Study Area comprises four parcels owned by the City of St. Helena (009-131-038-000, 022-190-002-000, 022-190-007-000, and 009- 131-013-000). Land uses surrounding the site include open space, residential, roadways, and agriculture (vineyards).
Based on the Soil Survey of Napa County (NRCS 1978), three soil types have been mapped within the Study Area. The soils are Henneke gravelly loam (154), Aiken loam (102), and Pleasanton loam (171). Henneke gravelly loam is restricted to the western edge of the reservoir and surrounding hillsides. This soil type is typically found at 30 to 75 percent slopes on uplands. It is excessively drained, runoff is rapid to very rapid, and there is a moderate to high hazard for erosion. The second soil type, Aiken loam, is restricted to the eastern edge of the reservoir and surrounding hillsides. Aiken loam is typically found at 30 to 50 percent slopes on steep uplands. It is well drained, runoff is rapid, and there is moderate hazard for erosion. The last soil type, Pleasanton loam, occurs along the south and southwestern edge of the reservoir and downslope. This soil type is found on gently sloping (2 to 5 percent slopes) alluvial fans. It is well drained, runoff is slow, and there is a slight hazard for erosion.
Most of the soils observed on the Study Area had matrix chromas different (either higher or lower) than those described for the mapped types. Soil texture was similar to all of the series described and ranged from loam to clay loam with some silt and gravel. Some areas contained non-native materials (e.g., rock
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 3 of 9
fragments) due to extensive past site disturbance. Overall, the soils observed on the Study Area did not closely match the mapped types.
RESULTS Wetland and Upland Determinations The west, north, and eastern edges of the reservoir are fringed by jurisdictional wetlands comprising 1.75 acres. A rock embankment along the southern edge of the reservoir lacks wetland characteristics, including vegetation and soil development. Hydrophytic vegetation dominates the wetland habitats and consists primarily of narrowleaf cattail (Typha angustifolia, OBL), tall cyperus (Cyperus eragrostis, FACW), curly dock (Rumex crispus, FACW-), and California bulrush (Scirpus californicus, OBL). Adjacent uplands are dominated by upland- classified plant species.
The wetlands receive hydrologic input from direct precipitation, runoff from the surrounding watershed, and, primarily, inundation and near-surface saturation from the adjacent reservoir. Positive wetland hydrology indicators observed in the wetlands consisted of saturated soils, drift lines, sediment deposits, and/or oxidized root channels in the upper 12 inches of soil profile. Adjacent upland areas appear well-drained and lack wetland hydrology indicators.
Soils observed in the wetlands consisted predominantly of clay loams with low chroma matrices (10YR 3/2, 2/2) and common (5 to 20 percent) and distinct redoximorphic mottles. Upland soil samples contained low to moderate chroma matrices (10YR 3/2, 3/3). One of the upland sample points contained hydric soils as indicated by the presence of mottles as a result of redoxomorphic activity. A second upland sample point contained mottles that appeared to be a result of rock fragments and not redoxomorphic activity.
The wetland/upland boundary was delineated based on the presence of a preponderance of hydrophytic vegetation, positive wetland hydrology indicators, and positive hydric soil indicators. The boundary between potential jurisdictional “other waters of the U.S.” and wetland habitats was delineated primarily based on the presence of vegetation in wetlands and a lack of vegetation in “other waters” (see below).
Other Waters of the U.S. The majority of the Study Area is dominated by an open, freshwater reservoir comprising 8.64 acres. As noted above, the west, north, and eastern edges of the reservoir are bordered by wetland habitat, and the southern edge is an
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 4 of 9 unvegetated riprap embankment. The reservoir, outside of wetlands habitat, is unvegetated, and no plants were observed in any of the sample points. The reservoir is likely a potential “other waters of the U.S.” rather than wetland due to the lack of vegetation and permanent inundation when at capacity.
The reservoir receives hydrologic input from direct precipitation and runoff from the surrounding watershed. Positive wetland hydrology indicators consisted of inundation, saturated soils, drift lines, and sediment deposits. Soils observed in the reservoir consisted of clay loams (many with rock fragments) with low chroma matrices (10YR 3/2, 2/2) and common (5 to 20 percent) and distinct redoximorphic mottles, meeting the hydric soil criteria for a wetland.
TABLE 1. DELINEATION PLOTS AND PRELIMINARY DETERMINATIONS Diagnostic Features Present: Plot Hydrophytic Hydric Preliminary Hydrology Number Vegetation Soils Determination 1A present present present Wetland 1B absent absent absent Upland 1C absent present present Other Waters of the U.S. 2A present present present Wetland 2B absent absent absent Upland 2C absent present present Other Waters of the U.S. 3A present present present Wetland 3B absent absent present Upland 3C absent present present Other Waters of the U.S. 4A present present present Wetland 4B absent absent absent Upland 4C absent present present Other Waters of the U.S.
REGULATIONS Jurisdictional wetlands and other waters of the U.S. are regulated by the Corps under the provisions of Section 404 of the Clean Water Act (33 United States Code [USC] § 1344) and Section 10 of the Rivers and Harbors Act of 1899 (33 USC § 403). Any disposal of dredged or fill material and structures, as well as work in wetlands or waters, requires a permit from the Corps. The Corps determines jurisdictional wetlands and/or other waters of the U.S. based on preliminary wetland delineations completed by wetland professionals and on-site evaluations and independent review by Corps staff.
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 5 of 9
Under Section 401 of the federal Clean Water Act, the Corps is required to meet state water quality regulations prior to granting a Section 404 permit for work in a creek, river, or drainage. This is accomplished by application to the local Regional Water Quality Control Board for Section 401 Certification that requirements have been met. In addition, the California Department of Fish and Game may regulate activities affecting or potentially affecting such resources. Wetlands may also be subject to the local city or county regulations where the project takes place.
REFERENCES
Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. Technical report Y-87-1, U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg, Mississippi.
Natural Resources Conservation Service (NRCS). 1978. Soil Survey of Napa County, California, Issued August 1978. http://www.ca.nrcs.usda.gov/mlra02/napa/
Natural Resources Conservation Service (NRCS). 2005. Hydric Soils of the United States, August 2005. http://soils.usda.gov/use/hydric/
Resource Management Group, Inc.(RMG). 1993. National List of Plant Species That Occur In Wetlands, Region 10 – California.
TOPO!. 2001. National Geographic (www.nationalgeographic.com).
FEDERAL REGULATIONS
33 CFR 328.3.
33 USC §403 (Section 10 of the Rivers and Harbors Act of 1899).
33 USC §1344, (Section 404 of the Clean Water Act).
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 6 of 9
PROJECT PHOTOGRAPHS
Photo 1. Conditions of the Lower York Creek Reservoir on April 13, 2006.
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 7 of 9
PROJECT PHOTOGRAPHS
Photo 2. Conditions of the Lower York Creek Reservoir on April 13, 2006.
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 8 of 9
PROJECT PHOTOGRAPHS
Photo 3. Conditions of the Lower York Creek Reservoir on June 19, 2006.
Preliminary Delineation of Wetlands and Other Waters of the U.S. Lower York Creek Reservoir Spring Mountain Road City of St. Helena, Napa County March 2007 Page 9 of 9
PROJECT PHOTOGRAPHS
Photo 4. Conditions of the Lower York Creek Reservoir on June 19, 2006.
Figure 1. Project Location Map. St. Helena USGS Quadrangle (Study Area indicated by red box.)
APPENDIX A DEFINITIONS AND ABBREVIATIONS
Wetlands: “The U.S. Army Corps of Engineers (Federal Register 1982) and the Environmental Protection Agency (Federal Register 1980) jointly define wetlands as: Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.” (Environmental Laboratory 1987)
Waters of the U.S.: Waters of the U.S. include, but are not limited to the following: any channel that has real or potential interstate commerce value including lakes, rivers, streams [including perennial and intermittent streams, and ephemeral streams that have an ordinary high water mark (OHWM)], tributaries to waters, mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa lakes, natural ponds, and impoundments of waters (33 CFR 328.3). The OHWM is described as the elevation delineating the highest water level that has been maintained for a sufficient period of time to leave evidence on the landscape.
Wetland Indicator Abbreviations OBL = Obligate Wetland Plant (estimated probability of occurring in wetlands >99%) FACW = Facultative Wetland Plant (estimated probability >67% to 99%) FAC = Facultative Plant (estimated probability 33% to 67%) FACU = Facultative Upland Plant (estimated probability 1% to <33%) UPL = Obligate Upland Plant (estimated probability <1%) (+) frequency towards the higher end of the category (more frequently found in wetlands) (-) frequency towards the lower end of the category (less frequently found in wetlands)
APPENDIX B ROUTINE WETLAND DELINEATION DATA FORMS
LOWER YORK CREEK RESERVOIR SPRING MOUNTAIN ROAD CITY OF ST. HELENA, NAPA COUNTY
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Wetland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID YES NO Is the area a potential Problem Area? (If needed, explain on seasonal Plot ID 1A reverse) wetland
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. Typha angustifolia (60%) Herb OBL 1. Cyperus eragrostis (10%) Herb FACW 2. 2. Rumex crispus (10%) Herb FACW- 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 100% Remarks: Sample point dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs ; Saturated in Upper 12 Inches Other Water Marks
; Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil 6 (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Pleasanton loam, 2 to 5% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Mollic Haploxeralfs Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 - 10” A 10YR3/2 10YR5/6 10% silty clay loam
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation ; Yes Present? No Is this Sampling Point Within a Wetland?
Yes ; Yes Wetland Hydrology Present? ; No No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in freshwater wetland fringing reservoir. All three parameters met. Plot located in a wetland.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 1A
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Upland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 1B reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. Lupinus sp. (20%) Herb NL 1. Quercus agrifolia (5%) Tree NL 2. Bromus diandrus (30%) Herb NL 2. Baccharis pilularis (5%) Shrub NL 3. Carduus pycnocephalus Herb NL 3. Rubus discolor (10%) Shrub FACW (20%) 4. Bromus hordeaceus (20%) Herb FACU- 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 0% Remarks: Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators not observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Pleasanton loam, 2 to 5% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Mollic Haploxeralfs Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 -10” A 10YR3/3 None None Gravelly loam
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Hydric soil indicators not observed.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; No ; No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in upland habitat. No wetland parameters met.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 1B
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Other Waters Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 1C reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. No vegetation present. 1. 2. 2. 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 0% Remarks: No vegetation within sample point. Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge ; Inundated Aerial Photographs ; Saturated in Upper 12 Inches Other Water Marks
; Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water 0 (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves 0 (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil 0 (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Pleasanton loam, 2 to 5% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Mollic Haploxeralfs Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 -10” A 10YR3/2 10YR5/6 10% silt clay loam
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; ; No No Sample point located in “other waters”.
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in open water habitat, reservoir. Two of three parameters met. Considered a potential jurisdictional “other waters” rather than wetland due to lack of vegetation.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 1C
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Wetland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID YES NO Is the area a potential Problem Area? (If needed, explain on seasonal Plot ID 2A reverse) wetland
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. Typha angustifolia (90%) Herb OBL 1. Cyperus eragrostis (5%) Herb FACW 2. 2. 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 100% Remarks: Sample point dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs ; Saturated in Upper 12 Inches Other Water Marks
; Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves 12 (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil 0 (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name: Henneke gravelly loam, 30 to 70% slopes Drainage Class: Excessively drained soils Taxonomy (Subgroup): Lithic Argixerolls Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast clay loam with 0 -12” A 10YR3/2 10YR4/6 5% rock fragments
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation ; Yes Present? No Is this Sampling Point Within a Wetland?
Yes ; Yes Wetland Hydrology Present? ; No No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in freshwater wetland fringing reservoir. All three parameters met. Plot located in a wetland.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 2A
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Upland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 2B reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. Bromus diandrus (25%) Herb NL 1. Centaurea sp. (10%) Herb NL 2. Bromus hordeaceus (25%) Herb FACU- 2. 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 0% Remarks: Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators not observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name: Henneke gravelly loam, 30 to 70% slopes Drainage Class: Excessively drained soils Taxonomy (Subgroup): Lithic Argixerolls Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 -10” A 10YR3/2 10YR5/6 40% loam with rock fragments
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Mottles appear to be a result of non-native rock fragments rather than redoxomorphic activity, and therefore the soils are not considered hydric due to a matrix chroma of 2 without redoximorphic mottles.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; No ; No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in upland habitat. No wetland parameters met.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 2B
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Other Waters Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 2C reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1.No vegetation present. 1. 2. 2. 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 0% Remarks: No vegetation within sample point. Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs ; Saturated in Upper 12 Inches Other Water Marks
; Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves 12 (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil 0 (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name: Henneke gravelly loam, 30 to 70% slopes Drainage Class: Excessively drained soils Taxonomy (Subgroup): Lithic Argixerolls Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast clay loam with 0 -10” A 10YR3/2 10YR4/6 5% rock fragments
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; ; No No Sample point located in “other waters”.
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in open water habitat, reservoir. Two of three parameters met. Considered a potential jurisdictional “other waters” rather than wetland due to lack of vegetation.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 2C
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Wetland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID YES NO Is the area a potential Problem Area? (If needed, explain on seasonal Plot ID 3A reverse) wetland
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator FAC± to 1. Typha angustifolia (40%) Herb OBL 1. Gnaphalium sp. (5%) Herb FACU FACW to 2. Scirpus californicus (40%) Herb OBL 2. Scirpus sp. (5%) Herb OBL 3. Cyperus eragrostis (20%) Herb FACW 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 100% Remarks: Sample point dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
; Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): ; Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Aiken loam, 30 to 50% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Xeric Haplohumults Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 -12” A 10YR2/2 10YR4/6 20% clay loam
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Rhyolite parent material, soil red color. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation ; Yes Present? No Is this Sampling Point Within a Wetland?
Yes ; Yes Wetland Hydrology Present? ; No No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in freshwater wetland fringing reservoir. All three parameters met. Plot located in a wetland.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 3A
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Upland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 3B reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. Arctostaphylos sp. (30%) Shrub NL 1. FAC to 2. Salix sp. (20%) Shrub 2. OBL 3. Quercus agrifolia (30%) Tree NL 3. 4. Bromus hordeaceus (40%) Herb FACU- 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 25% Remarks: Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators not observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Aiken loam, 30 to 50% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Xeric Haplohumults Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 -10” A 10YR3/2 10YR4/6 5% clay loam
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; No ; No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in upland habitat. One wetland parameter met.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 3B
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Other Waters Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 3C reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. No vegetation present. 1. 2. 2. 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 0% Remarks: No vegetation within sample point. Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
; Drift Lines ; No Recorded Data Available ; Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Aiken loam, 30 to 50% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Xeric Haplohumults Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 -12” A 10YR2/2 10YR4/6 20% clay loam
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; ; No No Sample point located in “other waters”.
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in open water habitat, reservoir. Two of three parameters met. Considered a potential jurisdictional “other waters” rather than wetland due to lack of vegetation.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 3C
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Wetland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID YES NO Is the area a potential Problem Area? (If needed, explain on seasonal Plot ID 4A reverse) wetland
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. Typha angustifolia (40%) Herb OBL 1. Cyperus eragrostis (5%) Herb FACW 2. Scirpus californicus (40%) Herb OBL 2. Polygonum sp. (5%) Herb NI to OBL 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 100% Remarks: Sample point dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
; Drift Lines ; No Recorded Data Available ; Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Aiken loam, 30 to 50% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Xeric Haplohumults Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast clay loam with 0 -12” A 10YR3/2 10YR4/6 10% rock fragments
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation ; Yes Present? No Is this Sampling Point Within a Wetland?
Yes ; Yes Wetland Hydrology Present? ; No No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in freshwater wetland fringing reservoir. All three parameters met. Plot located in a wetland.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 4A
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Upland Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 4B reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. Arctostaphylos sp. (40%) Shrub NL 1. 2. Briza maxima (20%) Herb NL 2. 3. Bromus diandrus (30%) Herb NL 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 0% Remarks: Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
Drift Line ; No Recorded Data Available Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators not observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Aiken loam, 30 to 50% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Xeric Haplohumults Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast 0 -10” A 10YR3/2 None loam
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Hydric soil indicators not observed.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; No ; No
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in upland habitat. No wetland parameters met.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 4B
DATA FORM ROUTINE WETLAND DETERMINATION (1987 COE Wetlands Delineation Manual)
Project/Site: Lower York Creek Reservoir Date 12/22/06 Applicant / Owner: City of St. Helena County Napa Investigator: Jennifer Michaud and Thomas Mahony State California Do Normal Circumstances exist on the site? YES NO Community ID Other Waters Is the site significantly disturbed (Atypical Situation)? YES NO Transect ID Is the area a potential Problem Area? (If needed, explain on YES NO Plot ID 4C reverse)
VEGETATION Dominant Plant Species Stratum Indicator Sub-dominant Plant Species Stratum Indicator 1. No vegetation present. 1. 2. 2. 3. 3. 4. 4. 5. 5. Percent of Dominant Species that are OBL, FACW, or FAC (excluding FAC-): 0% Remarks: No vegetation within sample point. Sample point not dominated by hydrophytic vegetation.
HYDROLOGY
Recorded Data (Describe in Remarks) WETLAND HYDROLOGY INDICATORS Primary Indicators: Stream, Lake, or Tide Gauge Inundated Aerial Photographs Saturated in Upper 12 Inches Other Water Marks
; Drift Lines ; No Recorded Data Available ; Sediment Deposits FIELD OBSERVATIONS Drainage Patterns in Wetlands
Depth of Surface Water None (in) Secondary Indicators (2 or more Required): Oxidized Root Channels in Upper 12 Inches Depth to Free Water in Water-Stained Leaves None (in) Pit Local Soil Survey Data FAC-Neutral Test Depth to Saturated Soil None (in) Other (Explain in Remarks) Remarks: Wetland hydrology indicators observed.
City of St. Helena, Lower York Creek Reservoir, Spring Mountain Road, Napa County
SOILS Map Unit Name (Series & Phase): Aiken loam, 30 to 50% slopes Drainage Class: Well drained soils Taxonomy (Subgroup): Xeric Haplohumults Field Observations Confirm Mapped Type? YES NO
PROFILE DESCRIPTION Mottle Depth Matrix Color Mottle Colors Texture, Concretions, Horizon Abundance/ (inches) (Munsell Moist) (Munsell Moist) Structure, etc. Contrast clay loam with 0 -12” A 10YR3/2 10YR4/6 10% rock fragments
HYDRIC SOIL INDICATORS: Histosol Concretions Histic Epipedon High Organic Content in Surface Layer in Sandy Soils Sulfidic Odor Organic Streaking in Sandy Soils Aquic Moisture Regime Listed on Local Hydric Soils List Reducing Conditions Listed on National Hydric Soils List ; Gleyed or Low-Chroma Colors Other (Explain in Remarks)
Remarks: Soil has moderately low chroma matrix and mottles. Hydric soil indicators observed.
WETLAND DETERMINATION
Hydrophytic Vegetation Yes Present? ; No Is this Sampling Point Within a Wetland?
Yes Yes Wetland Hydrology Present? ; ; No No Sample point located in “other waters”.
Yes Hydric Soils Present? ; No
Remarks: Sampling point located in open water habitat, reservoir. Two of three parameters met. Considered a potential jurisdictional “other waters” rather than wetland due to lack of vegetation.
DATA FORM – ROUTINE WETLAND DETERMINATION Plot ID: 4C
Appendix 5
Cultural Resources
Due to the confidential nature of cultural resource locations, several documents with sensitive information must remain confidential. Information contained in these documents will be made available on a “need to know” basis to protect and avoid impacts during construction activities. page 1 page 2
February 16, 2007
Steve Luna P.O. Box 164 Covelo, CA 95428
Re: Request for sacred lands search- Upper York Creek Dam and Reservoir and Lower York Creek Reservoir
Dear Mr. Luna,
The City of St. Helena (City) is working with the Army Corps of Engineers (Corps) on altering or removing a dam on Upper York Creek in Napa County, in the York Creek watershed. The “project site” is the Upper York Creek Dam. Dam materials and sediment may be placed at the Lower York Creek Reservoir (the “placement site”). The proposed project has been designed to improve fish passage, restore sediment transport and improve riparian and aquatic habitat. City has contracted with Prunuske Chatham, Inc. (PCI) to provide technical design and regulatory compliance for the project.
The project site is located in the Calistoga Quadrangle. The placement site is located in the St. Helena Quadrangle. Township, Range, and Section, as well as latitude and longitude, are provided below. The exact locations of the project sites are provided on the attached map.
Upper York Creek Dam-project site (note: this is also identified as St. Helena Upper 16 Dam) Township, Range, Section: T8N R6W Sec27 Latitude and longitude: 38 ۫ 30’49”N, 122 ۫ 30’05”W USGS Topo: Calistoga Quad
Lower York Creek Reservoir-placement site (note: this is also identified as the St. Helena Lower 16-002 Dam) Township, Range, Section: T8N R6W Sec26 Latitude and longitude: 38 ۫ 30’32”N, 122 ۫ 29’24”W USGS Topo: St. Helena Quad
PCI: Steve Luna February 16, 2007 Page 2 of 2
Please do a sacred lands search for the above-described project and placement sites with a 0.5 mile buffer on all sides and provide your written comments and/or concerns to me at your earliest convenience.
Thank you in advance for your assistance. Please give me a call if you have any questions about this request.
Sincerely,
Aimee Crawford Environmental Planner
Enclosures: Location Map Project Description
February 16, 2007
Mishewal-Wappo Tribe of Alexander Valley Earl Couey, Cultural Resources Manager P.O. Box 5676 Santa Rosa, CA 95402
Re: Request for sacred lands search- Upper York Creek Dam and Reservoir and Lower York Creek Reservoir
Dear Mr. Couey,
The City of St. Helena (City) is working with the Army Corps of Engineers (Corps) on altering or removing a dam on Upper York Creek in Napa County, in the York Creek watershed. The “project site” is the Upper York Creek Dam. Dam materials and sediment may be placed at the Lower York Creek Reservoir (the “placement site”). The proposed project has been designed to improve fish passage, restore sediment transport and improve riparian and aquatic habitat. City has contracted with Prunuske Chatham, Inc. (PCI) to provide technical design and regulatory compliance for the project.
The project site is located in the Calistoga Quadrangle. The placement site is located in the St. Helena Quadrangle. Township, Range, and Section, as well as latitude and longitude, are provided below. The exact locations of the project sites are provided on the attached map.
Upper York Creek Dam-project site (note: this is also identified as St. Helena Upper 16 Dam) Township, Range, Section: T8N R6W Sec27 Latitude and longitude: 38 ۫ 30’49”N, 122 ۫ 30’05”W USGS Topo: Calistoga Quad
Lower York Creek Reservoir-placement site (note: this is also identified as the St. Helena Lower 16-002 Dam) Township, Range, Section: T8N R6W Sec26 Latitude and longitude: 38 ۫ 30’32”N, 122 ۫ 29’24”W USGS Topo: St. Helena Quad
PCI: Mishewal-Wappo February 16, 2007 Page 2 of 2
Please do a sacred lands search for the above-described project and placement sites with a 0.5 mile buffer on all sides and provide your written comments and/or concerns to me at your earliest convenience.
Thank you in advance for your assistance. Please give me a call if you have any questions about this request.
Sincerely,
Aimee Crawford Environmental Planner
Enclosures: Location Map Project Description
February 16, 2007
Ya-Ka-Ama 6215 Eastside Road Forestville, CA 95436
Re: Request for sacred lands search- Upper York Creek Dam and Reservoir and Lower York Creek Reservoir
Dear Ya-Ka-Ama,
The City of St. Helena (City) is working with the Army Corps of Engineers (Corps) on altering or removing a dam on Upper York Creek in Napa County, in the York Creek watershed. The “project site” is the Upper York Creek Dam. Dam materials and sediment may be placed at the Lower York Creek Reservoir (the “placement site”). The proposed project has been designed to improve fish passage, restore sediment transport and improve riparian and aquatic habitat. City has contracted with Prunuske Chatham, Inc. (PCI) to provide technical design and regulatory compliance for the project.
The project site is located in the Calistoga Quadrangle. The placement site is located in the St. Helena Quadrangle. Township, Range, and Section, as well as latitude and longitude, are provided below. The exact locations of the project sites are provided on the attached map.
Upper York Creek Dam-project site (note: this is also identified as St. Helena Upper 16 Dam) Township, Range, Section: T8N R6W Sec27 Latitude and longitude: 38 ۫ 30’49”N, 122 ۫ 30’05”W USGS Topo: Calistoga Quad
Lower York Creek Reservoir-placement site (note: this is also identified as the St. Helena Lower 16-002 Dam) Township, Range, Section: T8N R6W Sec26 Latitude and longitude: 38 ۫ 30’32”N, 122 ۫ 29’24”W USGS Topo: St. Helena Quad
PCI: Ya-Ka-Ama February 16, 2007 Page 2 of 2
Please do a sacred lands search for the above-described project and placement sites with a 0.5 mile buffer on all sides and provide your written comments and/or concerns to me at your earliest convenience.
Thank you in advance for your assistance. Please give me a call if you have any questions about this request.
Sincerely,
Aimee Crawford Environmental Planner
Enclosures: Location Map Project Description
Project Description Upper York Creek Ecosystem Restoration
The project is the alteration or removal of the Upper York Creek Dam by the City of St. Helena (“City”) and restoration of the former reservoir area into a natural creek channel and native riparian corridor. In addition, the City will place materials removed from the dam and upper reservoir in the Lower York Creek Reservoir. The project will involve working in and on the banks of the Upper York Creek Dam and the Lower York Creek Reservoir (see attached map). Project objectives include:
• Restoration of sediment transport and prevention of future downstream flooding/sediment releases.
• Improved fish passage and habitat connectivity.
• Riparian and aquatic habitat restoration.
Under the plan proposed by the Corps, the water level of the Lower York Creek Reservoir would be temporarily lowered, and materials from the Upper York Creek Dam would be placed along the edge or bottom. The water would be allowed to return to its regular levels the following winter.
Appendix 6
Traffic Study Memo
T E C H N I C A L M E M O
Date: December 16, 2006
Subject: Upper York Creek Dam and Reservoir Traffic and Road Conditions
From: Laura Saunders
Caltrans has conducted traffic counts as part of structure and maintenance investigations on Spring Mountain Road, Main Street/SR 29, Deer Park and Silverado Trail, shown in Table 1.
Table 1. Caltrans Traffic Counts for Roads Affected by the Project
Road Average Annual Daily Trips Spring Mountain Road 1,500 Main Street /SR29 11,000 Deer Park 2,790 Silverado Trail 4,310
Counts were also taken on Spring Mountain Road for the project in order to differentiate time of day use to assess construction hour impacts. Vehicles were counted in 3 categories: trucks with 3 or more axles; large vehicles including 2-axle trucks using double rear tires, parcel vans and stretch limousines; and other vehicles including cars, pick-up trucks, passenger vans and SUVs. Vehicles were counted going separately headed up and downhill. During the count, numerous trucks and large vehicles went uphill and later came back down. This would be the same for trucks from the construction site, so each time past the counting station counted as a trip.
The count was taken just below the entrance to the lower reservoir. The entrance to Spring Mountain Vineyard is a little further uphill. This accurately represents the traffic load that would pertain to evaluating intersections in St. Helena. Only trucks going to Clover Flat or Fulton Lane would pass by the counting station. Prunuske Chatham: Technical Memo Upper York Creek Dam and Reservoir Traffic and Road Conditions December 2006 Page 2 of 2
Table 2. Traffic Counts on Spring Mountain Road
Uphill Downhill Time /day 3+ axle Large Other 3+ Axle Large Other of count trucks Vehicles Vehicles trucks Vehicles Vehicles 9/21 4:30- 0 4 35 2 3 38 5:00 9/29 8- 3 3 38 2 3 31 8:30 9/29 8:30- 1 1 23 1 2 23 9:00 9/29 9- 3 0 20 2 0 16 9:30 9/29 9:30- 1 3 12 5 0 10 10 9/29 10- 1 4 30 2 0 18 10:30 Hourly 3 5 52.7 4.7 2.7 45.3 average
Traffic counts were confirmed on October 19, 2006, from 4 pm to 5 pm. The hourly average for both up- and downhill traffic was consistent with the earlier counts. There are 113 total average trips per hour on Spring Mountain Road during the business day.
On August 22, 2006 road distances between sites were measured using the vehicle trip mileage odometer, with measurements to the nearest 1/10th of a mile. It is 6.2 miles on Spring Mountain Road from the edge of the densely developed portion of St. Helena to the top of the ridge. The Upper York Creek Dam and Reservoir is 2.4 miles from the developed area of St. Helena. The distance from the upper reservoir to the lower reservoir is 0.3 miles. Most of the project traffic will be on a 1.2-mile stretch of Spring Mountain Road that encompasses both reservoirs and both entrances to Spring Mountain Vineyard.