United States Department of Environmental Agriculture
Forest Assessment Service
February 2014 Trabuco District Dam Removal Project: Silverado, Holy Jim, and San Juan Creeks
Trabuco Ranger District, Cleveland National Forest Orange County, California
Location of Action: National Forest System lands on the Cleveland National Forest in Orange County, California
Type of Document: Environmental Assessment
Lead Agency: USDA Forest Service
Responsible Official: Trabuco District Ranger, Cleveland National Forest
Contact Person: Kirsten Winter, Forest Biologist Cleveland National Forest 10845 Rancho Bernardo Road, Suite 200 San Diego, California 92127
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Table of Contents
1 - Introduction ...... 1 1.1 Document Structure ...... 1 1.2 Location ...... 2 1.3 Purpose and Need for Action……………………………………………………………… 6 1.4 Decision Framework ...... 9 1.5 Public Involvement ...... 9 1.6 Issues ...... 9 2 - Alternatives, including the Proposed Action ...... 11 2.1 Alternative 1: Proposed Action ...... 11 2.2 Alternative 2: No Action ...... 16 2.3 Alternatives Considered but Not Analyzed in Detail ...... 16 2.4 Comparison of Alternatives ...... 17 3 - Environmental Consequences ...... 19 3.0.1 Scope of Cumulative Effects Analysis ...... 19 3.1 Physical Environment ...... 19 3.1.2 Air Quality ...... 22 3.1.1 Hydrology and Soils ...... 26 3.2 Biological Environment ...... 37 3.2.1 Threatened and Endangered Species ...... 37 3.2.2 Regional Forester’s Sensitive List Species ...... 40 3.2.3 Management Indicator Species………………………………………………………43 3.2.4 Migratory Bird Species ...... 44 3.3 Social Environment ...... 44 3.3.1 Recreation and Public Safety ...... 44 3.3.2 Cultural Resources ...... 46 4 - Persons, Groups, Organizations, and Agencies Consulted ...... 48 5 - References ...... 49 Tables Table 1. Comparison of Alternatives………………………………………………………….18 Table 2. Daily Project Emissions ...... 24 Table 3. Annual Project Emissions...... 25 Table 4. Daily Project Emissions, Regional Significance ...... 25 Table 5. Total Project Emissions ...... 25 Table 6. Sensitive species present in project area...... 40 Table 7: Management indicator species...... 43 Figures Figure 1: Locality and watershed map for fish dam removal project...... 3 Figure 2: Dams in Silverado Creek...... 4 Figure 3: Dams in Holy Jim Creek...... 5 Figure 4: Dams in San Juan Creek...... 6 Appendices Appendix A - Photographs of Typical Dams Appendix B - Response to Comments Appendix C - Best Management Practices
Chapter 1 Introduction
1.1 DOCUMENT STRUCTURE
This Environmental Assessment (EA) has been prepared in accordance with the National Environmental Policy Act of 1969 (NEPA), as amended; 7 CFR part 1b; 36 CFR 220; 40 CFR parts 1500 to 1508; the Forest Service Manual parts 1920 and 1950; and the Forest Service Handbook part 1909.12. This EA will disclose the direct, indirect, and cumulative environmental effects of implementing the proposed action and alternatives on the biological, physical and human environment. Analysis contained in this EA incorporates information from, and tiers to specialist reports in the project record, including but not limited to the air quality report, biological evaluation, historical assessment, engineering report, and hydrology report.
The document is organized into the following parts:
Chapter 1: Introduction. This chapter includes the background information on project area, the purpose and need for the project, and a description of the proposed action. Chapter 2: Alternatives. This chapter details how the public was informed of the proposal and how the public responded. This chapter provides a more detailed description of the proposed action as well as any alternative methods for achieving the stated purpose that may have been developed based on significant issues raised by the public and other government agencies during the scoping period. This chapter includes possible mitigation measures. Chapter 3: Environmental Consequences. This chapter describes the affected environment for each resource, as well as the environmental effects of implementing the proposed action and any other alternatives. Chapter 4: Agencies and Persons Consulted. This section provides a list of preparers and agencies consulted during the development of the environmental assessment. Appendices. The appendices provide more detailed information to support the analyses presented in the environmental assessment.
Additional documentation, including more detailed analyses of project-area resources, may be found in the project planning record located at the Cleveland National Forest Supervisor’s Office, 10845 Rancho Bernardo Road, Suite 200, San Diego, CA 92127.
1.2 LOCATION
The proposed action is to demolish up to 81 manmade dams in Silverado, Holy Jim, and Upper San Juan Creeks. The project area is located on the Trabuco Ranger District of the Cleveland National Forest (Forest). See Figures 1 through 4 for locations. Removal of four dams in Trabuco Creek was evaluated in a previous assessment (USDA Forest Service 2011); these dams are depicted in Figures 1 and 3 for context.
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Figure 1. Locality and watershed map for dam removal project.
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Figure 2. Dams in Silverado Creek.
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Figure 3. Dams in Holy Jim Creek.
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Figure 4. Dams in San Juan Creek.
1.3 PURPOSE AND NEED FOR ACTION
Improving fish passage opportunities through removal of dams and other types of barriers is a national initiative that is a priority for numerous federal and state agencies, including but not limited to the US Forest Service, US Fish and Wildlife Service, Federal Highway Administration, National Marine Fisheries Service, and the California Department of Fish and Wildlife. Removal of barriers is a key component in restoring stream health and function.
The purpose of the Trabuco District Dam Removal Project is to enhance aquatic organism passage and stream habitat in Silverado, Holy Jim, and Upper San Juan Creeks. Removing manmade dams in these creeks is essential to supporting native aquatic species and providing suitable habitat for potential re-establishment of extirpated species including southern California steelhead trout. This project would also eliminate public safety hazards created by these dams and restore natural stream processes. Each dam has been examined to determine if removal or partial removal is necessary to facilitate
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aquatic organism passage and/or improve stream habitat conditions. Eighty-one dams are targeted for removal.
In combination, the creeks discussed above contain remnants of approximately 100 dams, originally constructed to create pools for a stocked rainbow trout fishery, conserve water and wildlife, and provide water for fire suppression (Orange County Fish and Game Commission 1982). All of the dams were constructed by Orange County between the 1940s and mid-1970s using native rock combined with mortar. The dams were not built to provide for flood control and were never operated to provide for flood control. Most of the dams had a wooden gate that was placed in the center of the dam each spring to retain water through the summer. Gates were then removed in the fall to allow water to flow through the dam during winter storms. The wooden gates have not been installed for at least 20 years. Despite the presence of the gate openings, approximately 29 of the dams have completely failed and washed out during rainstorms. The dams that did not have gates - approximately 5 dams in Holy Jim Creek - have mostly been filled with sediment so they do not store water. See photos in Appendix A of this document for examples of dam structures. Several dams were removed by Orange County in the 1980s, with the assistance of the US Marines who used explosives to remove some dams that were creating safety hazards. Many of the remaining 81 dams are undermined, partially washed out, or have been damaged by storm events. Remnants and rubble associated with the failed dams is still visible. Since the gates are no longer used, the dams do not store water. Some dams have stored sediment.
Many of the remaining dams present a barrier to native fish and other aquatic organisms, especially during periods of low flow. Some dams alter physical stream processes such as bed load and sediment transport, natural surface flows, and channel adjustment. This has negative effects on aquatic species, aquatic habitat, and downstream habitat. The ability to move up and down stream is essential for aquatic species in order to complete their life cycles and maintain viable populations (Hoffman and Dunham 2007). Facilitating aquatic organism passage and improving stream habitat would ultimately increase accessible stream habitat for existing and potential populations of native aquatic species.
In addition, several dams are easily accessible and constitute safety hazards to Forest visitors. Serious injuries occurred in previous years when the gates were still being placed in the dams, as visitors were diving and swimming in the pools that were created upstream of each dam. Although the gates are no longer in use, people do still climb on the dams. There is extensive graffiti on many dams. Some dams have created plunge pools on the downstream side that are used for swimming and diving. This project would address safety concerns and reduce the risk of human injury associated with recreational use on or around these dams.
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Forest Land Management Plan Direction
This environmental analysis complies with the Cleveland National Forest Land Management Plan (LMP) which was completed in 2006. The proposed project area lies within the Silverado Place and the San Mateo Place as identified in the LMP.
Holy Jim and Silverado Creeks are within the Silverado Place. The desired condition for the Silverado Place is to maintain the area as a natural-appearing landscape that functions both as a backdrop for southern Orange County and a refuge for communities and the unique natural resources sheltered in the canyons. The program emphasis for the Silverado Place includes improving road maintenance for safety and to accommodate firefighting vehicles, as well as maintaining a road network to support the demand for scenic driving.
San Juan Creek is within the San Mateo Place. The desired condition for the San Mateo Place is to maintain a predominantly naturally evolving landscape that functions as an undeveloped day use wildland and wilderness retreat for southern Orange and Riverside counties. San Juan Creek is not within Wilderness. This creek is adjacent to the Ortega Highway. The program emphasis for the San Mateo Place is to maintain the undeveloped, primitive and semi-primitive character of the area, and to conserve opportunities for solitude and challenges within the San Mateo Wilderness.
The LMP shows that the Scenic Integrity Objective for both the San Mateo and Silverado places is “High”. The desired condition for scenery in these places, as shown above, is to emphasize a natural or natural-appearing landscape.
Goal 6.2 in the LMP deals with biological resource conditions (LMP, Part 1, pp. 44 to 45). In particular, this goal instructs the Cleveland NF to provide ecological conditions to sustain viable populations of native and desired nonnative species. The desired condition is to conserve habitats for federally listed species, and to recover listed species or to ensure that listed species are progressing toward recovery. Habitats for sensitive species and other species of concern are to be managed to prevent downward trends in populations and habitat capability and to prevent federal listing. Flow regimes in streams that provide habitat for threatened, endangered, proposed, candidate, and/or sensitive aquatic species and riparian-dependent species should be enhanced or maintained so that they are sufficient to allow the species to persist and complete all phases of their life cycles.
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1.4 DECISION FRAMEWORK
The Environmental Assessment (EA) discloses environmental effects of the no-action alternative and the proposed action. The Responsible Official, the Trabuco District Ranger, will make a decision based on review of the EA. The District Ranger’s decision will include:
1. Whether to proceed with the proposed action or “no action” alternative. 2. Whether the decision that is selected would have significant impacts. If a determination is made that no impact would be significant, then a “Finding of No Significant Impact” (FONSI) would be prepared. Significant impacts would require the preparation of an Environmental Impact Statement [40 CFR 1501.4 (c) and (e)].
The District Ranger’s decision will be documented in a separate Decision Notice (FSH, 1909.15 - 40).
1.5 PUBLIC INVOLVEMENT
A synopsis of the project proposal appeared continually in the Cleveland National Forest Quarterly Schedule of Proposed Actions (SOPA) beginning in January 2013. Scoping letters were sent to all individuals who have expressed an interest in Trabuco Ranger District projects. Legal notices were published in the Riverside Press-Enterprise and the Orange County Register on March 22, 2013, to begin a 30-day scoping period. Additional scoping occurred internally among USDA-Forest Service specialists and specialists from other state and federal agencies. The Orange County Register also printed an article about the project on April 14, 2013; this generated some further comments from the public. Approximately 50 responses were received based on the initial scoping letter. The draft Environmental Assessment was released for a 30-day public comment period beginning with legal notices published in the Riverside Press- Enterprise and the Orange County Register on September 24, 2013. Approximately 15 responses were received during the comment period on the draft Environmental Assessment.
1.6 ISSUES
The interdisciplinary team (ID team), considering public scoping, developed a list of key issues to be analyzed in this environmental analysis. Based on the comments received, the Forest added Alternatives 3 and 4 which examine the potential for adding fish ladders or repairing and maintaining dams. In addition, to address concerns about sediment release in Holy Jim Canyon, the proposed action was modified to include use of a
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temporary road to allow for mechanical removal of the lowermost, largest dams in Holy Jim Creek and the sediment that these dams have captured.
Effects of the project on air quality. This issue is analyzed in Section 3.1. Effects on water quality, watershed condition and soil conditions including potential flood and erosion risks. This issue is analyzed in Section 3.1. Effects on adjacent infrastructure including roads and buildings. This issue is analyzed in Section 3.1 and is addressed by additional information added to the proposed action, in Section 2.1. Effects on fish passage, suggestion that fish ladders should be installed. This issue is analyzed in Alternative 3, Section 2.3.
Effects on wildlife and plant species, especially for federally-listed threatened or endangered species and species considered sensitive by the Regional Forester. This issue is analyzed in Section 3.2. Effects on historic and cultural resources. This issue is analyzed in section 3.3. Effects on scenery; concern that dams are a scenic resource. This issue is analyzed in Section 3.3.
Effects on fire suppression resources. This issue is analyzed in Section 3.3.
A detailed list of comments, and responses to comments, appears in Appendix B. Key issues were defined as those directly or indirectly caused by implementing the proposed action. Non-key issues were identified as:
1. Outside the scope of the proposed action;
2. Already decided by law, regulation, Forest Plan, or other higher-level decisions;
3. Irrelevant to the decision to be made;
4. Conjectural and not supported by scientific or factual evidence; and,
5. Already addressed in the proposed action or alternatives.
The Council on Environmental Quality (CEQ) NEPA regulations require this delineation in Sec. 1501.7: “…identify and eliminate from detailed study the issues which are not significant or which have been covered by prior environmental review (Sec. 1506.3)…”
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Chapter 2 Alternatives
2 ALTERNATIVES, INCLUDING THE PROPOSED ACTION
Based on specialist review and public scoping, four alternatives were considered:
1- Proposed Action - dam removal 2- No Action 3- Fish Ladders 4- Repairing and Maintaining Dams
These alternatives are described in further detail below.
2.1 Alternative 1 - Proposed Action
The proposed action is to demolish up to 81 manmade dams in Silverado, Holy Jim, and Upper San Juan Creeks. Dams would be demolished to the point where they no longer restrict fish passage and/or impede physical stream processes. Demolition would also ensure the elimination of public safety hazards associated with the existing dams and the proper disposal of the remaining material. Material from the demolished dams would be broken down to appropriate size classes and distributed along the stream when possible. In some cases the materials would be used to reinforce or armor stream banks to protect infrastructure, or removed and recycled for use in other areas. In certain circumstances, dams may be partially demolished to protect adjacent infrastructure such as roads and retaining walls; in those cases, desired fish passage conditions would be achieved without jeopardizing adjacent infrastructure.
Demolition would likely be completed over the next three to five years during the fall months when stream water level is low and when threatened, endangered, and sensitive species (TES) are least likely to be in the project area.
Project implementation would be required to follow both National and Regional best management practices as defined in the Region 5 Forest Service Handbook (Direction 2509.22, Chapter 10: Water Quality Management Handbook, 2011) and National Best Management Practices for Water Quality Management on National Forest System Lands (USDA, 2012) . BMPs would be implemented to ensure compliance with the Clean Water Act and would minimize risk of short term impacts to water quality and beneficial uses. BMPs have been certified by the State Water Quality Resources Control Board (SWQRCB) and approved by the Environmental Protection Agency (EPA) as the most effective way to protect water quality from impacts stemming from nonpoint sources of
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pollution. Additionally, the Best Management Practices Evaluation Program is annual monitoring and reporting that the SWQRCB requires for ground disturbing activities. This project would be included in the sampling pool.
The following methods are proposed:
1. Dams accessible from adjacent roads including several dams in Silverado and Holy Jim Creeks may be demolished using an excavator to break up and re- distribute dam materials. If more advantageous, method 2 described below would be used to remove these dams. Hand crews may be used to assist with the break down and redistribution of dam material. If needed, dump trucks would be used to haul dam material away from the site. 2. Dams not accessible from roads, including all dams in San Juan Creek and upper Holy Jim Creek, would be demolished using pneumatic or gas-powered drills, jackhammers, non-toxic expanding mortars (safe for use in aquatic environments) and/or explosives. Materials would be re-distributed along the stream or in some cases used as bank protection. This latter work would be performed by hand crews. 3. At Holy Jim Creek, the lowermost 1,000 feet of the Holy Jim trail may be temporarily opened to vehicles to allow mechanical equipment to access and remove the lowermost dams and the stored sediment associated with these dams. This temporary road would be gated to prevent unauthorized use. In addition, for Holy Jim Creek, dam removal would occur over at least three years (in at least three phases) and possibly over a longer time period to allow stored sediment to disperse more gradually into the stream. 4. At Holy Jim Creek, the following methods would be used for removal of dams within 500 feet of roads or structures: an excavator, pneumatic or gas- powered drills, jackhammers, and/or non-toxic expanding mortars. 5. Forest engineers will provide technical advice on dams that may affect infrastructure. Approximately seven dams in Holy Jim Creek and four dams in San Juan Creek would have detailed engineering analyses so that they can be safely removed without damaging adjacent roads and structures.
The total area occupied by the existing dams is approximately 4 acres, or approximately 0.05 acre per crossing.
The Cleveland National Forest does not currently have funding for this project, but is pursuing funding through several grant opportunities as well as through National Forest funds that are set aside specifically for fish passage improvement.
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2.1.1 General resource protection measures
Resource protection measures and design criteria developed to protect and enhance aquatic habitat conditions and avoid or reduce adverse effects to federally listed species and Forest Service sensitive fish and wildlife species are included in the fisheries and wildlife biological assessment and biological evaluation. A summary of measures that relate to reducing soil disturbance, impacts to vegetation, and the spread of noxious weeds are included below:
1. All construction equipment would be washed prior to commencing construction to minimize the spread of non-invasive species in accordance with NS-8 Vehicle and Equipment Cleaning, Caltrans Storm Water Quality Handbooks, and Construction Site Best Management Practices Manual.
2. Ground-disturbing activity, such as heavy equipment use, would not occur during wet weather conditions.
3. Permanent and temporary spoils would be stored in a manner to prevent sediment delivery to any watercourse during and after project construction.
4. A water pollution control plan, in the event of inclement weather, would be developed to address water quality downstream of the dam removal sites. This plan would include actions to provide protective covering for excavated areas or soil stockpile areas.
5. Project activities would only occur during late summer and fall months when potential presence of Arroyo Toads is low. Most Arroyo Toad tadpoles will metamorphose by early July and the young toads will remain on sand and gravel bars near the stream for approximately 3-5 weeks. Project activities would not occur until late August or September at the earliest to reduce potential impacts on arroyo toads.
6. In areas where dams are adjacent to populations of Arroyo Chub, only mechanical breakdown of the dams or expanding mortar would be utilized for demolition. If necessary, Arroyo Chubs at risk of negative impacts from dam demolition actions will be captured and placed in temporary refugia until conditions warrant release to the capture site or relocation to nearby suitable habitat. Methods for capture and release would be determined by the Forest Fish Biologist in conjunction with California Department of Fish and Wildlife.
7. In areas where dams are occupied by or adjacent to Sticky Dudleya or Ocellated Humboldt Lily populations, these plant species would be salvaged and transplanted to nearby locations.
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8. The Forest Fish Biologist would confirm the presence/absence of aquatic TES species within the project area prior to project implementation and make appropriate adjustments to the demolition methodology, timing, order of implementation, placement of demolished material and number of on-site personnel to protect all TES species and habitat in the project area.
9. Blasting crews utilized for implementation would be experienced and trained for use of explosives in and adjacent to aquatic habitat. Blasting and hand crews would be trained to identify all aquatic TES species and would consult with the Forest Fish Biologist if TES species are present in the project area.
10. At sites where adjacent or downstream infrastructure is a concern, a Forest Engineer would provide a site specific decommissioning plan which may include use of the demolished material to stabilize stream banks, a staged decommissioning process and/or minimum action to be taken which allows aquatic organism passage but does not jeopardize infrastructure integrity.
11. Stream simulation would be used to ensure that the stream channel shape and gradient at each crossing is similar to the natural channel structure occurring along typical unmodified segments of the stream.
12. Scenic objectives for all areas would be met.
13. Best management practices for protecting water quality would be followed during removal of dams. These are listed in Appendix C.
14. Stream banks would be stabilized where necessary to minimize erosion and slopes will be tiered to minimize rock fall and slides
15. The project is expected to occur over the course of three to five years. After five years, environmental documents would be reviewed to determine if new species have been listed, or any other actions have occurred which cause a change in the decision. If no change would occur, the review would be noted and the project would continue.
2.1.2 Spill prevention
1. A spill prevention plan that details precautionary, preventative, and spill response measures sufficient to prevent resource damage from any fuels, lubricants or hydraulic fluids used or stored on site would be developed. The plan would include provisions for: (1) safely refueling equipment outside the 100-year floodplain; (2) storing any fuels, lubricants, or hydraulic fluids offsite or outside the 100-year floodplain and contained to prevent accidental spillage if containers are compromised; (3) emergency response measures adequate to rapidly contain
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and clean up any spills in a timely manner to prevent dispersal and contamination of soils or water resources, including onsite availability of a spill kit containing absorbent pads, booms, and a leak-proof container for storing contaminated spill cleanup materials; and (4) a reporting requirement that the Forest Service and any necessary emergency responders be notified immediately of any spills, with the stipulation that the spill and all response measures be thoroughly documented and delivered as soon as possible to the Cleveland NF hazardous materials coordinator. The Forest Service and other regulatory agencies may order cessation of operations, and cleanup and abatement if hazardous spills occur.
2. Self-contained sewage and grey water facilities would be present and the project operator would ensure and demonstrate that the sewage containment system is in good operating condition.
2.1.3 Spoils and fill
If excavated material is to be reused during construction, it would be stored at the existing flat staging areas to prevent sediment transport towards the stream.
2.1.4 Site-specific actions
The following specific actions, based on the conservation measures and terms and conditions from consultation with the U.S. Fish and Wildlife Service (2014), would be implemented to protect arroyo toads during project implementation. These actions would apply specifically to the San Juan Creek location, if Alternative 1 is selected.
1. “All field personnel shall be educated about the sensitive biological resources associated with the sites.
2. The qualified biologist shall inspect the demolition area for arroyo toads. Prior to any activity, the qualified biologist would conduct a briefing session for personnel involved in the project. If arroyo toads are found, the field personnel or project leader would contact the qualified biologist. The qualified biologist would relocate the arroyo toads out of the project area into nearby suitable habitat. No later than 30 days after completion of the proposed project, the qualified biologist would provide a written report documenting the number of arroyo toads removed from the project area, date and time of capture, specific location of capture, approximate size and age of individuals, and description of relocation sites.
3. The Forest will monitor and report on incidental take of arroyo toads associated with the proposed action. In the written report under item 2, the
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Forest will also report on any arroyo toads found dead or injured due to project activities. The CNF also will provide the CFWO a written report within 3 days of observing death or injury of arroyo toads potentially associated with project implementation. This report will include the date, time, and location of the observation. The purpose of this reporting to ensure that the project does not exceed estimated take levels.”
2.2 Alternative 2, No Action
The existing dams would remain in place. No action would be taken to accommodate aquatic organism passage.
2.3 ALTERNATIVES CONSIDERED BUT NOT ANALYZED IN DETAIL
Two alternatives were considered by the interdisciplinary team but were eliminated from detailed analysis because they did not adequately address the purpose and need for the project.
2.3.1 Alternative 3, Current structures plus fish ladders
This alternative would leave the current structures in place at each location. A fish ladder would be added to facilitate aquatic passage.
This alternative would not permit the stream gradient to be restored, nor would it permit the stream to return to its proper functioning condition. Fish ladders are expensive and are challenging for fish to negotiate. Although adult trout and steelhead may use a fish ladder, resident native fish such as Arroyo Chub do not have the ability to jump and use this type of structure.
Due to the reasons cited above, this alternative does not meet the purpose and need; therefore it was not analyzed in detail.
2.3.2- Alternative 4 – Repair and maintain 81 dams
This alternative would leave the current structures in place at each location. Eighty-one dams would be repaired and maintained.
This alternative would not permit the stream gradient to be restored, nor would it permit the stream to return to its proper functioning condition. Dam repair and maintenance would be very costly. Orange County abandoned maintenance and operation of the dams by 1992 due to “the cumulative detrimental effects of storm damage and siltation, curtailed maintenance, vandalism, usage conflicts, and liability lawsuits”. In 1982,
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Orange County estimated that the cost to repair dams would be $1,000 to $16,000 per dam (average of about $5,000 per dam), and maintenance costs would be approximately $500 annually per dam (Orange County Fish and Game Commission 1982). Adjusted for inflation, those costs would be an average of $12,000 per dam for repairs, and the cost for maintenance would be an average of $1,200 per dam each year or $97,200 for all 81 dams, not including additional repair and maintenance needed due to subsequent storm damage since 1982 (US Dept. of Labor 2013). Repairing and maintaining dams would not be consistent with Forest Plan direction regarding management of Riparian Conservation Areas, and would not implement the recovery plan objectives for steelhead.
Due to the reasons cited above, this alternative does not meet the purpose and need; therefore it was not analyzed in detail.
2.3 COMPARISON OF ALTERNATIVES
Table 1, shown below, compares the alternatives, the extent to which they meet the purpose and need of the project, and expected effects and costs.
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Table 1: Comparison of alternatives Alternative 1 Alternative 2 Alternative 3 Alternative 4 Criteria Proposed Action No Action Fish ladders Repair dams Meet Forest Service design Yes No No No requirements Meets Forest Plan objectives Yes No No No for riparian areas Implements steelhead Yes No No No recovery plan objectives Restores natural streambed and removes barriers to Yes No In part No aquatic organism passage Removes safety hazards Yes No No No May cause traffic delays Yes No Yes Yes Adequately accommodates stream flow Yes No No No Life expectancy Unknown, permit is Maintenance Maintenance Indefinite expired required required Estimated demolition cost per dam $4,000 each, or Not applicable Not applicable Not applicable $324,000 for all Estimated repair cost per dam $90,000 each #, $12,000 each*, or construction cost for fish None None or $7.29 million or $972,000 for ladder for all all Estimated annual maintenance Not estimated $1200 each*, or None None cost per dam $97,200 for all *Based on Orange County estimates in their 1982 operations plan, adjusted for inflation # Based on estimated cost of a fish ladder for a 10 foot high dam
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Chapter 3 Environmental Consequences
This chapter provides an overview of the physical, biological, and social environments of the project area and the potential changes to those environments that would result from implementing each of the alternatives. Included in this analysis is an assessment of the cumulative effects of the alternatives on the physical, biological, and social environments. This chapter also presents the scientific and analytical basis for comparison of the two alternatives presented in Chapter 2 of the EA.
3.0.1- SCOPE OF CUMULATIVE EFFECTS ANALYSIS
This section describes the scope of cumulative effects used for analysis of the two alternatives for the physical, biological, and social environments. Cumulative impacts are those impacts resulting from the incremental impact of an action when added to other past, present, or reasonably foreseeable actions. The cumulative effects and the scope of the cumulative effects analysis for each type of resource are summarized within each resource section. Unless separately defined for a resource area, the cumulative effects analysis area is the watersheds in which the project is located (Figure 1).
3.1 – PHYSICAL ENVIRONMENT
Project areas are located along a variety of stream channel types from narrow bedrock canyons to wide alluvial arroyos between 900 and 2,400 feet above sea level. Most dams proposed for removal occur in perennial (or nearly perennial) stream reaches dominated by a coast live oak/sycamore/white alder riparian forest. In combination, the creeks analyzed in this document contain remnants of at least 100 dams originally constructed to create pools for a stocked rainbow trout fishery. Many dams were originally constructed in the 1940s with additional construction in the late 1960s and mid-1970s. All dams were built using native rock combined with mortar tied into or laid on top of bedrock and/or large boulders. Some of these dams have since failed or were partially removed; however, many dams are still intact. The existing dams present a barrier to native fish and other aquatic organisms, especially during periods of low flow. Dams alter physical stream processes such as bed load and sediment transport, natural surface flows and channel adjustment which negatively affect aquatic species and their habitat. In total, 81 dams appeared to negatively influence fish passage and/or physical stream processes and these 81 dams are included in the project areas described in this document. Habitat conditions specific to each drainage are presented below.
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SAN JUAN CREEK
San Juan Creek from the Forest boundary upstream to Upper San Juan Campground is largely contained within a narrow bedrock canyon, but occasional broad valley arroyos do occur forming an alternating sequence of constrained and unconstrained reaches. During the early 2013 project survey conducted by fisheries biologists, San Juan Creek maintained surface flow throughout a majority of the survey area despite below average precipitation. Stream substrate is dominated by bedrock, boulders and cobbles and large woody debris is infrequent which is typical for the channel type. Aquatic species observed during the survey included California tree frogs, arroyo chub, red swamp crayfish and other macro-invertebrates.
San Juan Creek is the largest stream and thus contained the largest dams. Some dams appeared to be partially removed or eroded naturally, but 27 of the 31 dams surveyed have some impact on fish passage and/or physical stream processes such as sediment transport. Intact dams in San Juan Creek typically raised the stream bed elevation by over 1 foot and up to 5 feet effectively eliminating upstream movement of native Arroyo Chub and creating significant obstacles to future steelhead movement. Dams with narrow spillways that are 6 to 9 feet wide have created potential pinch points where debris can lodge and ultimately limit fish movement. Other dams with narrow spillways have accumulated enough sediment to create an unnatural area of down-welling and subsurface flow, ultimately limiting fish passage. Often, sediment retained by the dams was of a suitable spawning size class for steelhead. Spawning gravels were largely absent towards the downstream end of existing dams, but as surveyors moved upstream a higher percentage of gravel was observed, typically upstream of large dams.
The potential upper extent for steelhead in San Juan Creek is likely upstream of the confluence with Lion Canyon in an entrenched valley with a relative high number of large pools. Above this reach, the multiple canyons which come together to form San Juan Creek do not appear to maintain surface flows or habitat that would support steelhead. Adequate surface flow will likely be the most important factor determining successful spawning of steelhead in San Juan Creek. Furthermore, a single Arizona crossing approximately 600 feet upstream of the Forest boundary on San Juan Creek may limit native chub and steelhead movement upstream.
Another limiting factor for native species and potential steelhead is the presence of invasive species. In 2011, red swamp crayfish, golden shiner and mosquito fish were found alongside native Arroyo Chub in the lower reaches of San Juan Creek near the State Highway 74 Bridge. Competition with these species and lack of upstream mobility caused by the dams may have a significant toll on chub recruitment and population viability over the long term. Invasive riparian vegetation including giant reed and French broom were also observed along San Juan Creek, but distribution is currently limited to a few small patches.
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HOLY JIM CREEK
Holy Jim Canyon is similar to San Juan Creek but is contained within a broader valley. The surrounding area is characterized by steep chaparral-covered slopes. Along Holy Jim, the vegetation type is Oak-Sycamore-Alder woodland with other riparian species such as mule fat and poison oak. Introduced fig trees are common in Holy Jim Canyon. Stream substrate is dominated by boulders, cobble and gravel. The presence of large woody debris increases from lower reaches of Trabuco Creek to upper Holy Jim which creates additional habitat complexity in Holy Jim. Stocked rainbow trout were observed in some large pools in Trabuco Creek and winter stoneflies were emerging during the winter 2013 surveys. No frogs or other fish species were observed during the 2013 survey likely due to a precipitation event which lowered water temperatures.
Holy Jim Creek contains the largest number and greatest density of dams in the survey area. A total of 41 dams were surveyed, 38 of which were recommended for some degree of demolition due to existing or potential effects on the stream. Twenty-two dams in Holy Jim Creek are suspected barriers for adult steelhead due to substantial jump heights (up to 8 feet). Most dams are clustered together near trail access points, creating a series of obstacles for upstream movement. Several dams in upper portions of Holy Jim are nearly buried by sediment from a previous flood, and in one case the stream re-routed around the original channel because sedimentation behind the dams altered the natural flow path.
Two Arizona crossings in lower Holy Jim Creek are barriers to fish passage. Sediment runoff at these crossings causes high turbidity and sediment fouling similar to the crossings in Trabuco Creek. Several user created dams (stacked rocks) and a low water ford exist in Holy Jim Creek near the recreation residence cabins which may impede fish movement. Several recreation residences have retaining walls built on the edge of Holy Jim Creek which restrict flow to a narrow channel in a few locations. Upstream of the Arizona crossings and residences, a trail to Holy Jim Falls crosses the creek at several locations. The trail is a moderate source of fine sediment in Holy Jim Creek. Despite fine sediment impacts in this drainage, adequate steelhead spawning habitat is available and successful spawning of stocked rainbow trout is suspected downstream in Trabuco Creek. Potential habitat for steelhead exists upstream to the reach below Holy Jim Falls, a large natural waterfall that precludes fish movement further upstream.
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Although no other aquatic species besides stocked rainbow trout were observed during the 2013 surveys, several other non-natives have been documented in Trabuco Creek including goldfish, green sunfish and bullfrogs. A cabin owner in the area also claimed to have moved stocked rainbows from Trabuco Creek to large pools in Holy Jim Creek. Other native species including California Newts, Western Toads and California Tree Frogs have also been documented in Trabuco by Forest biologists. In 2011, Arroyo Chub were documented between the Forest boundary and the 2nd Arizona crossing. The Arizona crossings in Trabuco Creek and stocked rainbow trout are key limiting factors for native chub. Should steelhead be able to reach the Forest portions of Trabuco Creek, existing populations of stocked rainbows may breed with wild steelhead.
SILVERADO CREEK
Silverado Creek displays the same general channel characteristics as San Juan and Trabuco Creeks, but the valley is steeper with a higher frequency of steps and small cascades. Stream bed material is dominated by boulders and gravel/sand size classes are highly embedded throughout the creek. Large wood is present but not in quantities that would affect habitat complexity. No aquatic species were documented during the 2013 surveys, but a Forest volunteer and other Forest biologists identified goldfish in the outlet pool of one of the large dams.
Seven dams are proposed for removal on Silverado Creek. Some user created dams exist in Silverado, similar to those in Holy Jim Creek, which may hamper native fish movements during low flows. Several Arizona crossings are also barriers to fish passage, but have little effect on stream habitat or water quality because the road in Silverado is paved and receives little vehicle use compared to Trabuco Canyon. Turbidity and fine sediment were reflective of good habitat conditions in Silverado Creek, but the substrate is highly embedded. The geology of Silverado Canyon likely influences substrate embeddedness and the current substrate condition seems natural for the area.
3.1.1 Air Quality
The air quality analysis for the proposed project is provided below in its entirety.
Alternative 1 - Proposed Action
Climatic Conditions
Southern California’s sunny weather, dense populations, and confining mountain valleys often combine to create poor air quality conditions. This project lies in the South Coast
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Air Quality Management District (SCAQMD). SCAQMD is considered to be in non- attainment for both state and federal air quality standards. The climate in the project area is best described as Mediterranean, with mild winter temperatures, low precipitation and warm, dry summers. High summer temperatures add to the Ozone load on the area as terrestrial ground level Ozone is a photochemical reaction enhanced by high air temperatures.
Regulatory Framework
The federal Clean Air Act (CAA) as amended in 1990, specifies in Section 176(a) that no department, agency, or instrumentality of the federal Government shall engage in, support any way, or provide financial assistance for, license or permit, or approve, any activity which does not conform to an implementation plan after it has been approved or promulgated under Section 110 of this title. Conformity is defined in Section 176(c) of the CAA as conformity to the applicable State Implementation Plan (SIP) and its purpose of eliminating or reducing the severity and number of violations of the National Ambient Air Quality Standards (NAAQS) while achieving expeditious attainment of such standards, and that the activities will not:
(i) cause or contribute to any new violation of any standard in any area; or (ii) increase the frequency or severity of any existing violation of any standard in any area; or (iii) delay timely attainment of any standard or any required interim emission reductions or other milestones in any area.
South Coast Air Quality Management District (SCAQMD) is a federal nonattainment area for ozone, which is a byproduct of photochemical reactions between nitrogen oxides (NOx) and reactive organic compounds/Gasses (ROC/ROG). The region is also a federal nonattainment area for particulate matter less than 2.5 microns (PM2.5). SCAQMD is also in State nonattainment for PM10, PM2.5, Ozone, and NO2. The General Conformity rule requires a Conformity Analysis for any federal action that would cause emissions of NOx, ROC, or PM2.5, in excess of the de minimis levels established in the rule.
Assumptions
The nearest Air Quality monitoring site is operated by SCAQMD and located at about 11 miles from the project area. The project falls completely within the Cleveland National Forest; the minimum distance from the closest project site to the forest boundary is approximately 0.5 miles. There are approximately 81 complete and remnant stream grade control structures impeding stream flow and fish migration in the project area. They are proposed for either major modification and/or complete removal of their impediment to water flow. Modification or removal of these barriers would be expected to take three to five years to complete. There are 81 of these small dam-like structures in the project area. They resemble short retaining walls, extending across the channels with
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an average width of about 24 feet and an average height of 3 feet. It is anticipated that structures would be removed one at time and the debris rearranged in place to accommodate channel and stream dynamics. Dust and fine particulate matter (PM 2.5), generated by this removal operation would be minimal, occurring for only a few hours at a time, and not be transported beyond the Forest boundary at detectable concentrations.
For this analysis, sources of air pollution are grouped into two main categories, on-road and off-road. On road in this case is limited to equipment and crew transport. Off-road includes equipment like air compressors and excavators. Daily project emissions are based on a five year project life and 4 month operating period, allowing for 400 total work days.
Table 2 below shows the daily estimated emissions from this project and compares the results to the local air district thresholds of significance. In this case, potential emissions of ROC, PM10, and CO from demolition of some, all, or portions of the channel grade control structure obstructing fish migration are considered. Any debris from this operation would be rearranged in place so as not to further impact fish migration. On the average one grade control structure would be completely demolished or greatly modify per day. Daily emissions would not exceed the daily SCAQMD significance thresholds under CEQA.
Table 2. Daily Project Emissions NOx ROC PM10 CO Emission Sources (lb/day) (lb/day) (lb/day) (lb/day) Off-Road Equipment 18.83 13.76 0.22 68.23 On-Road Mobile Vehicles 0.62 0.39 0.07 3.72 Fugitive Dust ------2.26 --- Total Daily Emissions 19.45 14.15 2.58 71.95 SCAQMD Significance Thresholds 100 75 150 550 Project Less Than Threshold? Yes Yes Yes Yes
Estimated Total Annual Project Emissions.
Direct and indirect emissions caused by the project on an annual basis are needed to complete the General Conformity applicability analysis. The nature of this activity, demolition and debris spreading, would result in a limited duration of emissions, totaling about 60 days per year over a five-year period.
Table 3 shows the annualized project emissions and compares them to the de minimis levels in the General Conformity rule. De minimis values represent annual emissions that are less than significant and will have no adverse effect on air quality in SCAQMD. The annual emissions would be below the de minimis levels.
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Table 3. Annual Project Emissions NOx ROC PM10 CO Emission Sources (tpy) (tpy) (tpy) (tpy) Off-Road Equipment 1.74 0.62 0.08 4.92 On-Road Mobile Vehicles 0.00 0.00 0.00 0.03 Fugitive Dust ------0.01 --- Total Annual Emissions 1.75 0.62 0.09 4.96 Conformity Rule Applicability Level 10 10 100 100 Project Less Than Threshold? Yes Yes Yes Yes .
Table 4 shows that the project emissions would be less than 10 percent of the total regional emissions. If a project’s total annual emissions make up less than ten percent of the total area emissions, in this case SCAQMD, and are below de minimis levels no air quality impacts are anticipated.
Table 4. Daily Project Emissions, Regional Significance NOx ROC PM10 CO Emission Sources (ton/day) (ton/day) (ton/day) (ton/day) Total Daily Emissions 0.010 0.007 0.001 0.036 Regional Significance Thresholds 95 70 29 397 Project Less Than Threshold? Yes Yes Yes Yes
Table 5 shows the total mass of emissions that would occur over the five year life of the project.
Table 5. Total Project Emissions – Over The Five Year Life of Project NOx ROC PM10 CO Emission Sources (ton) (ton) (ton) (ton) Off-Road Equipment 8.72 3.09 0.39 24.62 On-Road Mobile Vehicles 0.01 0.02 0.00 0.17 Fugitive Dust ------0.07 --- Total Emissions 8.73 3.12 0.46 24.75
Because annual project emissions would be less than the General Conformity rule applicability levels and daily project emissions would be less than 10 percent of the total
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emissions in the region, the project conforms to the State Implementation Plan and it would not be expected to cause any significant local or regional air quality impacts.
Alternative 2, No Action
Direct, indirect, and cumulative effects to air quality: This alternative would have no effect on air quality.
3.1.2 Hydrology and Soils
The effects of the alternatives on hydrology and soils were analyzed in a Hydrology Report prepared for this project and contained in the project record. This section presents a summary of the findings from this analysis.
In the summer of 2012 Jason Wilcox, a USFS fisheries biologist from the Siuslaw National Forest, initiated a habitat assessment and small dam inventory on the Cleveland National Forest. The focus of his efforts was concentrated on the Trabuco District in San Mateo, Trabuco and San Juan Creeks. He documented general habitat conditions and aquatic species occurrence/distribution in these creeks during the summer dry season. He also began an inventory of small dams or “Fish Dams” in San Juan Creek. In January 2013 Nick Ettema (USFS fisheries biologist - Inyo National Forest) and Greg Robertson (Forest Service TEAMS fisheries biologist) completed a fish dam inventory in San Juan, Trabuco, Holy Jim and Silverado Creeks. Some additional habitat assessment and species occurrence was documented in Jan-Feb 2013 to build on the data gathered during the 2012 season. This information forms the basis for this analysis and is located in the project planning record.
In addition to these surveys, best available science, literature reviews, current Geographical Information System (GIS) data, the FS WEPP model, and professional judgment were also used to support report conclusions.
Stream surveys and visual assessments of the locations by a Forest Service Hydrologist were conducted in March 2013. The dams were also visited and evaluated by a Forest Service Geotechnical Engineer.
Trabuco Creek is a perennial stream and is part of the Arroyo Trabuco Hydrologic Unit Code (“HUC”) 6 Watershed. The surrounding area is characterized by steep chaparral- covered slopes. Soils at project sites are mapped as Riverwash and Soboba cobbly loamy sand (USDA Soil Conservation Service 1978).
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Spatial and Temporal Context for Effects Analysis
Effects analysis for this project considers direct, indirect and cumulative effects. Spatially, for these effects the context is the same—the boundaries of the 6th level watersheds. The area of analysis for potential direct and indirect and cumulative effects is displayed in Figure 1.
This level of analysis (6th level) was selected for two reasons. It provides a good scale for determining potential effects. If a larger scale was used, the amount of area tends to be overwhelming and when smaller scales are used the amount of area is too limited in scope. In addition, interpretation of “watershed” effects at 6th HUC scale is appropriate because they represent the smallest drainage areas that have been formally mapped.
Two levels of temporal context used in the effects analysis are short-term effects, defined as less than 10 years, and long-term effects, defined as greater than 10 years. These periods are based on professional judgment and the fact that this project would take approximately 5-8 years to implement.
Past, Present, and Foreseeable Activities Relevant to Cumulative Effects Analysis
Activities to be considered in the cumulative effects discussion for watershed include:
Continued operation and maintenance of the recreation cabins in Trabuco and Holy Jim Canyons. Continued operation and maintenance of the existing roads and trails in all project area watersheds. Ongoing removal of non-native plant species through herbicides in all project area watersheds. Construction of four bridges to replace the existing low water crossings in Trabuco Canyon. NEPA on this action was completed in 2011.
Alternative 1 - Proposed Action
The proposed action is to demolish or partially demolish up to 81 manmade dams in Silverado, Holy Jim, Trabuco and Upper San Juan creeks. Dams would be completely demolished to the point where they no longer restrict fish passage and/or impede physical stream processes. Material from the demolished dams would be broken down to appropriate size classes and distributed along the stream when possible. In some cases the materials would be used to reinforce or armor stream banks to protect infrastructure, or removed and recycled for use in other areas. On occasion, dams may be partially demolished to protect adjacent infrastructure such as roads and retaining walls. In this case, desired fish passage conditions would be achieved without jeopardizing adjacent infrastructure.
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Demolition would likely be completed over the next 3 to 5 years during the fall months when stream water level is low and when threatened and endangered species concerns are least likely to be in the project area. The following methods are proposed:
1. Dams accessible from adjacent roads including several dams in Silverado and Holy Jim creeks may be demolished using an excavator to break up and re- distribute dam materials. If more advantageous, method 2 described below would be used to remove these dams. Hand crews may be used to assist with the break down and redistribution of dam material. If needed, dump trucks would be used to haul dam material away from the site.
2. Dams not accessible from roads, including all dams in San Juan Creek and dams in upper Holy Jim Creek, would be demolished using pneumatic or gas-powered drills, jackhammers, non-toxic expanding mortars (safe for use in aquatic environments) and/or explosives. Materials would be re-distributed along the stream or in some cases used as bank protection. This latter work would be performed by hand crews.
3. At Holy Jim Creek, the lowermost 1000 feet of the Holy Jim trail may be temporarily opened to vehicles to allow mechanical equipment to access and remove the lowermost dams and the stored sediment associated with these dams. This temporary road would be gated to prevent unauthorized use. In addition, for Holy Jim Creek, dam removal would occur over at least three years (in at least three phases), and possibly over a longer time period to allow stored sediment to disperse more gradually into the stream.
4. At Holy Jim Creek, the following methods would be used for removal of dams within 500 feet of roads or structures: an excavator, pneumatic or gas-powered drills, jackhammers, and/or non-toxic expanding mortars.
5. Forest engineers would provide technical advice on dams that may affect infrastructure. Approximately seven dams in Holy Jim Creek, and four dams in San Juan Creek would have detailed engineering analyses so that they can be safely removed without damaging adjacent roads and structures.
Design Features and Mitigation Measures
Design features have been incorporated into the project to mitigate or reduce adverse impacts and achieve desired outcomes. These measures were guided by the direction in the Forest Plan, project-specific objectives, and concerns identified by the Forest Service and the public during scoping. A list of project design features can be found in Section 2.1 of the EA.
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Project Design Features, including BMPs, site-specific mitigations, and Forest Plan Standards and Guidelines, were incorporated into the development of this project to ensure compliance with Section 208 of the Clean Water Act, the Porter-Cologne Water Quality Control Act, and the Santa Ana and San Diego Basins Regional Water Quality Control Board and their Basin Plans. Hence, there is anticipated to be no deleterious effects to beneficial uses of water.
Forest Service Soil and Water Conservation Practices, or BMPs, have been designed to protect and restore watershed resources (USDA Forest Service, 1990). BMPs have been certified by the State Water Quality Resources Control Board and approved by the Environmental Protection Agency (EPA) as the most effective way to protect water quality from impacts stemming from nonpoint sources of pollution. Throughout the Forest Service, BMPs have been developed over time based on research, monitoring, and modification, to ensure the measures are effective (Burroughs and King, 1985; Burroughs and King, 1989; Burroughs, 1990; Seyedbagheri, 1996; Schuler and Briggs, 2000; USDA Forest Service, 2002). The following BMPs, taken from the Forest Service National Core Best Management Practices handbook (July 27, 2010), have been incorporated into the planning and design of this project:
Plan-1. Forest and Grassland Planning
Plan-2. Project Planning and Analysis
Plan-3 Streamside Management Zone (SMZ) Planning
AqEco-1. Aquatic Ecosystem Improvement and Restoration Planning
AqEco-2. Operations in Aquatic Ecosystems
AqEco-4. Stream Channels and Shorelines
Fac-2. Facility Construction
Fac-10. Facility Reclamation
Road-2. Road Location and Design
Road-5. Temporary Roads
Road-6. Road Storage and Decommissioning
Road-7. Stream Crossings
Road-9. Parking and Staging Areas
Road-10. Equipment Refueling and Servicing
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Uses-6. Dam Removal
The full description of these BMPs is located in the project planning record and in Appendix C of the EA.
BMPs and other measures comprise the Design Features for this project. By incorporating these measures, substantial conflicts with hydrologic resources would be avoided, and potential impacts either eliminated or mitigated so that effects are within acceptable levels.
Direct and Indirect Effects of Proposed Action
This alternative may have potential effects to sediment and turbidity, flooding risk to infrastructure, channel morphology and water quality. The potential effects include both short and long term effects. In general the long term effects of the project are positive for every variable considered. The short term effects are both positive and negative. The following sections describe the range of predicted effects to hydrological resources.
Fine Sediment/Turbidity
Dam removal work would be accomplished when little to no flow is present in the stream channels during the autumn months. Therefore increases in fine sediment in the water column and turbidity would not occur during dam removal activities.
The increase in fine sediment transport would occur after the first significant rains occur most likely in late autumn and early winter. We anticipate a relatively short term (less than one hour) period of higher turbidity in the streams as fine grained materials are eroded out of the new path and entrained in the flow. Following this initial flush, turbidity levels would decline as the streams clear the finer grained substrates and continue to flow across the remaining coarser materials. The increased stream turbidity may deposit fine coats of sediment on channel substrate for a short distance downstream (approximately 0.5 – 1.0 miles downstream of the project reaches). This increase in sediment and turbidity is expected to be within the natural range of variability for these systems after the first significant precipitation and flow events in the stream channels.
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Over the following wet season or seasons (depending on stream flow), fine sediments are likely to continue to erode out from the newly exposed channels. Because stream flows can be variable during the winter months in the Santa Ana Mountains, there may initially be insufficient stream energy to move larger materials such as the gravel and cobble that dominate the streambed upstream of the dam. The limited energy of the stream at that time would also be less than required to alter the stream grade of the newly exposed channel. As a result, turbidity levels during this time maybe elevated, but only slightly. As stream flow volumes increase during wetter seasons, the new channel behind the dam would enlarge and begin to work back through the accumulated sediments that have been stored behind the dam. During this process, movement of both coarse and fine-grained sediments would increase in the systems. Turbidity increases occurring at this time would be coincident with natural rises in turbidity that occur each fall and winter in streams throughout the watershed.
There is the potential for small increases in fine sediment production from the approximately 1,000 feet of temporary road construction proposed in lower Holy Jim Canyon. This temporary road is being constructed so that a portion of the sediment stored in lower Holy Jim Canyon just above the last recreational residence can be trucked off site. This temporary road would be located along the bottom of Holy Jim Creek using the current Holy Jim trail. Several road crossings are anticipated. This road is expected to be opened for one season and then converted back to a trail. The increase in fine sediment is expected to be less than what would be released if the stored material, proposed to be trucked offsite, were left onsite and transported downstream naturally after dam removal. Implementation of Forest Service BMPs Road 2 - Road Location and Design, Road 5 - Temporary Roads, and Road 7 - Stream Crossings is expected to protect overall water quality. After dam removal is complete, decommissioning of this temporary road would follow BMP Road 6- Road Storage and Decommissioning, further protecting soil and water resources.
Coarse Sediment/Substrate
Between 200-1,000 tons of sediment comprised largely of sand, gravel and cobble are stored behind the dams in the four reaches. In winter months following dam removal, it is anticipated that streamflow would increase to the level that this material is mobilized. The new channels immediately upstream of the dams would work back to a stable grade and increase their width and depth to fit the flow volume. As this occurs, coarse sediments would be eroded and moved downstream. The smaller particles would be likely to travel further downstream than the larger materials, and in this way the total volume of sediment moved from the site would over time be dispersed throughout lower reaches of the Silverado, Holy Jim, Trabuco, and San Juan Creek systems.
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Due to the variability of rainfall and stream flow in these southern California systems from year to year; it is hard to estimate when the upstream dam material would be transported. It may take several years if low water years occur and one year if an El Nino event happens. Over time following dam removal, an estimated volume of less than 200 tons of material in Silverado, less than 300 tons in Trabuco, and less than 1,000 tons in both Holy Jim and San Juan Creeks would move some distance downstream to accommodate the development and re-establishment of the channel upstream of the dam at an appropriate grade. It is expected that a small portion of the trapped material would remain in the watersheds even after the dams have been removed. These volumes of material represent approximately 20% of the estimated annual erosion potential of the Silverado Canyon system, approximately 15% of the Trabuco Canyon system, over 100% of the Holy Jim Canyon system and approximately 20% of the San Juan Canyon system. We feel that the slight increase in coarse sediments caused by dam removal in the Silverado, Trabuco, and San Juan Canyon drainages would mimic, for example, impacts from a small wildfire, landslide, or flood and are not out of the natural range of variability for these systems. The Holy Jim Canyon system is storing the same amount of erosion that is produced in the watershed each year and issues with sediment transport may occur if mitigations are not implemented.
Flooding/Risk to Infrastructure
Silverado Canyon: There are seven dams proposed for removal in this Canyon, all upstream of the community of Silverado. After removal of the dams, it is expected that the fill material (approximately 200 tons) that has been trapped behind the dams would be mobilized and fill in the downstream pools and adjust the stream channel gradient accordingly. This fill material represents approximately 20% of the overall potential erosion of the watershed. This represent a small disturbance, one in which the system has evolved with through major flood, fire and landslide activity. Because of this, no increased flooding or lateral channel migration is anticipated. Because of this no undermining of Forest Road 5S04 or impacts to the houses that line the channel approximately 0.2 miles below are anticipated.
Holy Jim Canyon: There are thirty-eight dams proposed for removal in this Canyon, primarily upstream of the Holy Jim Canyon recreational residences. They also sit above Forest Road 6S14, Forest Trail 6W03 (Holy Jim Trail upstream to the Holy Jim Falls), and the Trabuco Canyon Road bridge that crosses over Holy Jim.
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After removal of the dams, it is expected that a large portion of the fill material (approximately 1,000 tons) that has been trapped behind the dams would be mobilized and fill in the downstream pools and adjust the stream channel gradient accordingly over time. Holy Jim would see a significant change in sediment transport due to the relatively large amount of sediment trapped in a relatively small drainage (~3,200 acres). It is estimated that the amount of sediment stored behind the dams is equal to the annual potential erosion for the Holy Jim system, so potentially a major increase in sediment to the channel. Channel capacity may be reduced by this rearranging of bedload material. There is the potential for an unusually large storm event(s) to change the channel through the recreation residence tracts and impact cabins, the road, and the bridge as evidenced by the past levee building on the Holy Jim Road.
The recreational tract cabins sit in an area that is naturally prone to flooding as evidenced by the stream terraces where the recreational cabins are located as well as the documented flood events that occurred in 1937, 1965, 1969, 1998, 2008, and 2010. No matter if Alternative 2 is implemented or not, there is a natural flooding risk to the existing structures due to the flashy nature of the system and the location of where they were built. It is anticipated, that should the implementation of the dam removal be staggered over several years that this would reduce the risk of increased flooding to natural levels. Further, a CNF engineer would provide a site specific decommissioning plan which may include use of the demolished material to stabilize stream banks, off site removal of some of the trapped sediment, a staged decommissioning process and/or minimum action to be taken which allows aquatic organism passage but does not jeopardize infrastructure integrity. It is anticipated that this would reduce the risk of damage to cabin and bridge infrastructure below.
Trabuco Canyon: There are four dams proposed for removal in this Canyon, all downstream of the Trabuco and Holy Jim Canyon recreational residences. The removal of these dams was addressed in a prior Environmental Assessment USDA Forest Service 2011), and is included here for context. The Trabuco Canyon Road and the 4 individual low water crossings are located within the reach as well. After removal of the dams, it is expected that the fill material (approximately 300 tons) that has been trapped behind the dams would be mobilized and fill in the downstream pools and adjust the stream channel gradient accordingly. This fill material represents 16% of the overall potential erosion of the watershed above. This in itself represents a small percentage of the annual load that is transported through the Trabuco Canyon watershed. However, the Trabuco Canyon reach is downstream of the Holy Jim reach, which has dams that are holding approximately 1,000 tons of material behind them.
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Should all the dams in Holy Jim and Trabuco Canyons be decommissioned at once, there would be increased potential for impacts to the four low water crossings and Forest Road 6S13 during higher flow events. By staggering the dam removal in Holy Jim Canyon as well as implementing additional mitigation measures listed in Appendix B, risks to infrastructure in Trabuco Canyon would be on par with the risk that exist naturally there now. Prior to the low water crossings being replaced with bridges, clearing of the low water crossings after significant runoff events may be needed until the material is worked through the system, but damage to these crossings is not anticipated with implementation of mitigation measures. Replacement of the low water crossings with bridges (as proposed in the completed Trabuco Aquatic Organism Passage Restoration EA completed in 2011), would allow the additional bedload to pass downstream without impacts.
San Juan Canyon: There are twenty-seven dams proposed for removal in this Canyon. One of the dams is near a retaining wall built for Highway 74 (Ortega Highway) and may impact the structural integrity. Forest Service and Caltrans engineers would develop a site specific decommissioning plan for this site ensuring it’s protection. The recreational resident tracts just downstream of the Ortega Highway Bridge sit high up on historic stream terraces and would only be impacted should an unprecedented flooding event occur. The flood elevation would not be influenced by whether the dams are in place or not.
Channel Conditions/ Riparian
Removal of dams within the Silverado, Trabuco, Holy Jim, and San Juan Creeks would eliminate the artificial barriers that are currently created by the dams, and would begin the process of hydrologically and biologically reconnecting the channels through the project reaches and beyond. In Silverado, San Juan, and Holy Jim Creeks removal of the dams would mean barrier free systems on Forest Service lands where bedload would not become trapped but rather move through the system naturally. Four low water crossings in the Trabuco Canyon reach would remain after this project and act as sediment traps to both bedload and fine materials.
Sediments presently stored behind the dams would begin to move downstream during periods of higher flow, and the channel immediately upstream of the dam would re-grade to fit the valley slope and better match the grade of upstream and downstream reaches.
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The blasting process may introduce some variability in the channel bed and banks at individual dam locations. Small pieces of concrete may remain attached to the bedrock channel bottom or small chunks of rock and soil may be removed from the native channel by the force of the blast. In either case, the channel deviations caused by blasting would not have significant effects on channel processes in the long term. As the streams regrade and re-occupy their pre-dam channel, coarse substrates currently behind the dams would be moved downstream to the dam sites and beyond. These substrates along with other sediment and woody debris that is routed through the reach or that is brought in by other natural disturbance processes would over time obscure evidence of the dams and the blast.
Riparian condition throughout the stream reaches is expected to improve under the proposed action. Removal of the dams would restore natural hydrology processes and add to the surface area where riparian vegetation may potentially grow. The flooding regime would be restored and fine sediment deposition on floodplains has the potential to increase riparian species composition.
Water Quality
Petroleum/Chemical Contamination: Use of a gas powered rock drill would create the potential for short term contamination of Silverado, Holy Trabuco, Holy Jim, and San Juan Creeks from petroleum products that inadvertently drip into the water. In addition, use of explosives near the creek may contribute chemical contaminants into the stream water. Best Management Practices would be used to minimize both the potential for and the magnitude of these eventualities. In particular, conducting the project during fall ensures that water levels in the stream and onsite would be at annual minimums. Further, absorbent diapers and floating booms would be onsite and employed to intercept and capture any petroleum that would otherwise enter the streams.
Ammonium Nitrate-Fuel Oil (ANFO) and Emulex would be used to create the blast that would remove and pulverize the dam. These two products are commonly used by the Forest Service for blasting purposes and have a well-established track record. They have been used extensively in stream environments to remove failing culverts, bridges and road embankments in areas inaccessible to heavy equipment. They were recently used to remove Minneopa Dam in Montana (2010), and have been used in the 2010 project to deepen the shipping channel in the Columbia River.
303 (d) listed and TMDL streams: None of the pollutants would be impacted as the cause of this listing is from urban impacts and land developments in the lower parts of the watersheds.
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Cumulative Effects
Past, present, and reasonably foreseeable projects were disclosed in an earlier section of this document. They include continued use and maintenance of the roads and residence tracts in each of the applicable cumulative effects watersheds. Additional projects include the use of herbicides for non-native species eradication as well as the potential for the replacement of four low water crossings to bridges in Trabuco Canyon. None of these projects when added to the Trabuco District Dam Removal Project would cause further deleterious effects to the flooding regime, sediment transport, channel morphology, riparian health and water quality in any of the project area watersheds. This is due to the fact that these activities currently occur in the watershed and the only change would be the implementation of the Dam Removal Project and the removal of the low water crossings in Trabuco Canyon.
The combination of projects however does have the potential to improve the overall watershed condition of several of the factors listed as fair or poor by the CNF during the WCAT protocol performed in 2010.
This project when combined with the past, present and reasonably foreseeable projects would improve the fair aquatic biota condition, fair riparian/wetland vegetation condition, and poor aquatic habitat that are currently degraded in the Arroyo Trabuco watershed. This is due to the fact that no artificial barriers would exist within the watershed on CNF lands, allowing for migration of aquatic species and proper transport and deposition of water and sediment. Water quality is expected to remain in the same poor condition. This is due to the urban setting of the downstream portion of the watershed as well as the location of the Trabuco Canyon Road that would continue to impact sedimentation of Trabuco Creek. The overall condition of the Arroyo Trabuco watershed is expected to remain in a functioning at risk state even after the implementation of this project mainly from road impacts associated with the Trabuco Canyon Road and the urban impacts below the CNF boundary.
For the Santiago/Silverado Canyon watershed, the good aquatic biota condition is expected to continue or improved, riparian/wetland vegetation condition is expected to improve due to restoration of the hydrologic regime, water quality remain poor, and aquatic habitat improved. The overall condition of the Santiago/Silverado Canyon watershed is expected to remain in a functioning at risk state even after the implementation of this project due to the poor water quality caused by urban development.
For the Upper San Juan Creek watershed, the poor aquatic biota condition would improve as well as the poor riparian/wetland vegetation and poor aquatic habitat condition. Good water quality is expected to continue. The overall condition of the Santiago/Silverado Canyon watershed is expected to remain in a functioning at risk state even after the implementation of this project.
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Alternative 2, No Action
Under the no action alternative, there would be no immediate change to the existing dams in Silverado, Trabuco, Holy Jim, or San Juan Canyons. The dams have been in place for between 40-80 years, and unmaintained for at least the past 25 years. There would continue to be no maintenance on these dams in the future.
Over the past 25 years, various parts of the dams have been damaged, buried, or have slowly deteriorated, but they continue to effectively interrupt the upstream and downstream connectivity of Silverado, Trabuco, Holy Jim, and San Juan Canyons for coarse sediment and fish and aquatic organism migration. There is no indication that the effects of the dams would change in the near future in terms of their effect on sediment transport, channel morphology, or passage for fish and aquatic species. The overall water quality of these systems is not being impacted directly by the dams and this is expected to remain static into the future.
As the existing dams continue to deteriorate due to the lack of maintenance, there is increased risk of catastrophic failure in the future. These risks are highest in Holy Jim and Trabuco Canyons. These dams were never intended to provide flood control or protection for downstream values at risk. If the no action alternative is selected, these dams have a high probability of failure sometime in the future. Should this happen, there is the potential for a large amount of material to be released at one time during higher precipitation events that has historically occurred in these Canyons. The release of this material would increase the risk that stream channel movement and avulsion may occur, thus increasing the risk for damage to downstream infrastructure in all the Canyons.
3.2 BIOLOGICAL ENVIRONMENT
The effects of the proposed action on special status wildlife and plant species were analyzed in a Biological Assessment, Biological Evaluation, Management Indicator Species Report, and a Migratory Bird Report prepared for this project and contained in the project record. This section presents a summary of the findings from this analysis. The total area to be directly affected by dam removal is approximately 4 acres.
3.2.1 Threatened and Endangered Species
Alternative 1 - Proposed Action
Arroyo Toad
Direct effects: At Holy Jim Creek and Silverado Creek dams, no direct effects would be expected from Alternative 1 because arroyo toads do not occur in the project area. The
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nearest occurrences of the species have been near the Forest boundary, 0.5 to 2.0 miles downstream from the project area.
At the San Juan Creek dams, direct effects may result from the proposed action due to disturbance in occupied habitat. Heavy equipment and explosives may injure or kill toads during project work.
Indirect effects: In Holy Jim Creek and Silverado Creek, indirect effects of the project may include increases in erosion and quantities of sediment in the stream during and after dam demolition. Due to the distance between the project area and the areas currently inhabited by arroyo toads, the indirect effects related to erosion would be expected to be too small to measure. The long-term effect of the project would be beneficial as it would allow for more natural stream flows and deposition rates.
In San Juan Creek, indirect effects may include increases in erosion and quantities of sediment in the stream during and after demolition. This may harm or kill any toad eggs in the immediate downstream area.
Cumulative effects: The Endangered Species Act defines cumulative effects as those effects of future state or private activities, not involving federal activities, that are reasonably certain to occur in the action area of the federal action subject to consultation. Future federal actions would be analyzed through separate Section 7 consultations and are not considered in this section.
The upper reaches of Holy Jim Creek have recreation facilities including a trailhead, trails, and two recreation residence cabin tracts. These areas are a potential source of sediment and water pollution. Due to the distance between the Holy Jim project areas and occupied arroyo toad habitat, the Forest Biologist determined that the demolition of dams would have no effect on arroyo toads, and will not contribute to cumulative effects on this species. Over the long term the project would have a beneficial effect beause the project would allow more natural water flows and sediment deposition along streambanks.
The upper reaches of Silverado Creek contain Maple Springs Road which is a Forest road. The upper reaches of San Juan Creek contain Forest Service campgrounds, a recreation residence tract, and the Ortega Highway. All upstream facilities are managed by the Forest Service or are under permit from the Forest Service and have been addressed in previous consultations. Because there are no private or non-federal actions in the portions of the upper watersheds that are suitable arroyo toad habitat, the current project will not contribute to cumulative effects on the species. Over the long term the project would have a beneficial effect because the project would allow more natural water flows and sediment deposition along streambanks.
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Southern Steelhead
Direct and indirect effects:
No direct or indirect effects would be expected from the proposed action, as steelhead cannot currently access the portion of the streams that is on National Forest System lands. The nearest occurrences have been near the confluence of Trabuco Creek and San Juan Creek about 15 miles downstream from the project area. Over the long-term, as downstream barriers are removed or mitigated, the proposed action would allow steelhead to access spawning areas on the Cleveland National Forest. Due to the absence of direct and indirect effects, no cumulative effects would be expected for this species.
The National Marine Fisheries Service performed an extensive review of southern California Steelhead for the 2012 Recovery Plan. They determined that tributaries within the Southern California Steelhead Recovery Planning Area, including the San Juan Creek/Arroyo Trabuco watershed, were historically occupied and have the potential to support steelhead in the future once man-made barriers are removed.
The impediments created by multiple fish-passage barriers within each creek are a concern addressed by the Southern California Steelhead Recovery Plan (NMFS 2011). We fully recognize that restoring suitable habitat conditions for steelhead migration, spawning, and rearing of young will require multiple management actions by several agencies over many years. The Southern California Steelhead Recovery Planning Area includes portions of the coastal watersheds that are currently inaccessible to steelhead due to man-made barriers. The National Marine Fisheries Service has identified physical modification of barriers such as road crossings, highways, and railways as a critical recovery action in the Recovery Plan (NMFS 2011). Modification of these fish passage barriers is a necessary first step to providing functional habitat to steelhead and other native fish. In recognition of this, the Forest is working proactively to remove the barriers from our lands as funding is available. In addition, the Southern California Steelhead Recovery Planning Area (NMFS 2011) includes portions of the coastal watersheds that are only seasonally accessible to migrating steelhead. While it is true that, due to relatively low average rainfall in the region, many of the drainages are seasonally dry or can have extensive dry portions, steelhead will attempt to move upstream into upper portions of a stream when water flow conditions are favorable for migration. The Mediterranean climate of southern California has long dry summers, and brief winters with short, intense storms. Steelhead have been a part of this ecosystem for a very long time and have adapted to the “flashy” hydrologic conditions. While climate change predictions suggest storm and drought cycles may be amplified in the future, steelhead would have opportunities to migrate upstream in tributaries when the flow conditions are favorable.
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Alternative 2 - No Action
Direct, indirect, and cumulative effects to the arroyo toad and steelhead trout: No known occupied arroyo toad habitat would be directly affected by implementing this alternative. No known occupied steelhead habitat would be directly affected by implementing this alternative. Sediment movement would still occur during heavy rainfall and flooding. This may have some effect on the habitat for both the arroyo toad and steelhead trout. Effects to the arroyo toad may be scouring of pools and removal of sandy banks due to excessive flows caused by channeling of water through the current openings in the dams. This would reduce the quality of the habitat for arroyo toad. No indirect effects would be expected to occur to steelhead because they do not currently have access to project areas.
3.2.2 Regional Forester’s sensitive list species
Table 6 lists sensitive species that have the potential to occur in the project areas.
Table 6: Sensitive species that may occur in the project areas. Holy Jim, and Plants San Juan Creek Silverado Sticky Dudleya (Dudleya viscida) Known No potential Heart-leaved Pitcher Sage (Lepechinia cardiophylla) Potential Potential Chaparral Beargrass (Nolina cismontana) Potential Potential San Miguel Savory (Satureja chandleri) Known Potential Wildlife Coastal Rosy Boa (Lichanura trivirgata roseofusca) Potential Potential Two-striped Garter Snake (Thamnophis hammondii) Potential Potential San Diego Mountain Kingsnake (Lampropeltis zonata pulchra) Potential Potential San Diego Ring-necked Snake (Diadophis punctatus similis) Potential Potential Red Diamondback Rattlesnake (Crotalus ruber ruber) Potential Potential San Diego Horned Lizard (Phrynosoma coronatum blainvillei) Potential Potential California Legless Lizard (Anniella pulchra) Potential Potential Orange-throated Whiptail (Aspidocelis hyperythra) Potential Potential Southwestern Pond Turtle (Emys marmorata pallida) Potential Known Arroyo Chub (Gila orcuttii) Known Known Pallid Bat (Antrozous pallidus) Potential Potential Townsend’s Big-eared Bat (Corynorhinus townsendii) Potential Potential Fringed Myotis (Myotis thysanodes) Potential Potential
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Two sensitive wildlife species are known to occur in the project area. The Arroyo Chub occurs in Trabuco Creek, within and adjacent to the creek crossings. The Southwestern Pond Turtle occurs in Holy Jim Creek, upstream from the creek crossings. All the sites contain potential habitat for eleven additional sensitive wildlife species, shown in Table 6.
Alternative 1, Proposed Action
Plants: No sensitive plants were located during field surveys, with the exception of a few Sticky Dudleya plants on or adjacent to dams in San Juan Creek, and some San Miguel Savory plants which occur on upper slopes above San Juan Creek.
Wildlife: Arroyo Chubs were observed in Trabuco Creek during field visits. Southwestern Pond Turtle is known to occur in the Holy Jim/Trabuco Creek area. The project area contains potential habitat for ten additional sensitive wildlife species, as shown in Table 6. These species may be affected by project implementation.
Loss and/or alteration of habitat: All species listed above are known or expected to occur in the project areas. Coastal Rosy Boa, San Diego Horned Lizard, California Legless lizard, and Southwestern Pond Turtle all require at least temporarily friable soils that allow burrowing for refugia. Compaction of these soils due to use of heavy equipment during dam removal would effectively preclude use of some areas by these species. The total area to be directly affected by dam removal is approximately 4 acres.
Direct effects: Demolition of dams may cause mortality of any sensitive species that are known or may occur in the project areas. Arroyo Chub, Southwestern Pond Turtle, Coastal Rosy Boa, Two-striped Garter Snake, San Diego Mountain Kingsnake, San Diego Ring- necked Snake, Red Diamondback Rattlesnake, Orange-throated Whiptail, San Diego Horned Lizard, and California Legless Lizard potentially may be run over by construction traffic at the project sites. Direct effects may occur due to accidental spills or deliberate release of chemical contaminants. These effects would be short term. Over the long term, restoration of stream gradients and opportunities for fish passage would have a beneficial effect on wildlife species in the project area.
Indirect effects: The project may include increases in erosion and quantities of sediment in the stream during and after demolition of dams. The long-term effect of the project would be beneficial because it would allow for more natural stream flows and deposition rates, and would reduce fragmentation of habitat for these species.
Cumulative effects: Within the project watersheds (see Fig. 1), sensitive species are currently affected by recreational activity, man-made stream structures and diversions, introduced exotic plant and animal species, and Forest Service roads and trails. These activities can result in direct mortality or habitat alteration or loss. The proposed project
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may add to these effects by temporarily increasing vehicular traffic and disturbing habitat in the project area.
Heavy equipment would be needed to complete demolition and transport materials. Construction vehicles may kill or injure sensitive species throughout project areas. Construction vehicles may also increase the spread of exotic “weedy” plants by transporting seeds from one disturbed site to another in their tires and undercarriages. Construction sites would have areas of disturbed soil preferred by fast-growing, high- reproducing exotic plant species. Construction traffic may also increase the chance of hazardous chemical spills on the access roads. These chemicals may indirectly enter the stream channel; organisms may be killed or displaced as the result of chemical exposure. The proposed project may contribute to cumulative effects on species in the project vicinity.
Determinations
Plants: No sensitive plants were located during field surveys, with the exception of a few Sticky Dudleya plants on or adjacent to dams in San Juan Creek, and San Miguel Savory on the slopes above San Juan Creek. No effects on heart-leaved pitcher sage and chaparral beargrass would be anticipated as a result of project implementation. The project may affect individual Sticky Dudleya and San Miguel Savory plants. Due to the large size of the Sticky Dudleya population in San Juan Canyon – over 20,000 individuals, and the large size of the San Miguel Savory populations in adjoining areas, implementation of the proposed action would not lead to a trend toward federal listing or a loss of viability for this species.
Wildlife: Two sensitive wildlife species are known to occur in the project area. Arroyo Chub occurs in Trabuco Creek and San Juan Creek. Southwestern Pond Turtle occurs in Holy Jim Creek, upstream of Trabuco Creek. All sites contain potential habitat for ten additional sensitive wildlife species, as shown in Table 6.
Based on the loss of habitat, potential for direct mortality, and indirect and cumulative effects that are expected to occur, the Forest Biologist determined that demolition of dams at Silverado, Holy Jim and San Juan creeks may affect individual Arroyo Chubs, Southwestern Pond Turtles, Coastal Rosy Boas, Two-striped Garter Snakes, San Diego Mountain King Snakes, San Diego Ring-necked Snakes, Red Diamondback Rattlesnakes. Orange-throated Whiptails, San Diego Horned Lizards, California Legless Lizards, Pallid Bats, Townsend’s Big-eared Bats, and Fringed Myotis. Based on the relatively small acreage affected by the project, the Forest Biologist determined that project implementation would not be likely to result in a trend toward federal listing or a loss of viability for these species.
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Alternative 2 - No Action
Direct, indirect, and cumulative effects to sensitive species: Based on the loss of habitat, potential for direct mortality, and indirect and cumulative effects that may occur due to altered stream flows, no action at the dam sites may affect individual Arroyo Chubs, Southwestern Pond Turtles, Coastal Rosy Boas, Two-striped Garter Snakes, San Diego Mountain King Snakes, San Diego Ring-necked Snakes, Red Diamondback Rattlesnakes, Orange-throated Whiptails, San Diego Horned Lizards, California Legless Lizards, Pallid Bats, Townsend’s Big-eared Bats, and Fringed Myotis. However, the determination was made that for sensitive species, this alternative would not lead to a trend toward federal listing for any sensitive plant or wildlife species or their habitat.
3.2.3 Management indicator species
Table 7 lists management indicator species that occur in the project area.
Table 7: Management indicator species. Species Indicators of management Relevance to project Mountain lion Fragmentation Occurs in project area Mule deer Healthy diverse habitats Occurs in project area Arroyo toad Aquatic habitats Occurs in project area Song sparrow Riparian habitats Occurs in project area
Alternative 1, Proposed Action
Effects on the mountain lion: Demolition of 81 dams would not be expected to contribute to habitat fragmentation. The project would not reduce the amount of habitat available for this species. The proposed project would not be expected to contribute to habitat and population trends for mountain lion or cumulative effects on this species.
Effects on the mule deer: Demolition of 81 dams would not be expected to contribute to habitat fragmentation. The project would not reduce the amount of habitat available for this species. The proposed project would not be expected to contribute to habitat and population trends for mule deer or cumulative effects on this species.
Effects on the song sparrow: Demolition of 81 dams would not be expected to contribute to habitat fragmentation. The project would not reduce the amount of habitat available for this species. The proposed project would not be expected to contribute to habitat and population trends for song sparrow or cumulative effects on this species.
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Effects on the arroyo toad: Demolition of 81 dams would be expected to have short term adverse effects, and long term beneficial effects on arroyo toad populations and habitat. Overall, the proposed project would not be expected to contribute to habitat and population trends for arroyo toad or cumulative effects on trends for this species.
Alternative 2 - No Action
The No Action Alternative would not contribute to habitat fragmentation and would not reduce the amount of habitat available for mountain lion, mule deer, song sparrow or arroyo toad and would not contribute to cumulative effects on these species.
3.2.4 Migratory birds
Alternative 1 - Proposed Action
Given the limited effect of the project on riparian habitat, implementation may affect some migratory bird species or their associated habitats. Potential impacts to migratory species would be minimized by doing demolition work outside of the nesting season. Over the long term migratory birds would benefit from the project as riparian habitat recovers. Due to the relatively low acreage affected by the project, and the short duration of effects on migratory birds, the project would not be expected to contribute to cumulative effects on migratory bird species.
Alternative 2 - No Action
The No Action Alternative would not affect migratory birds or their habitat and would not contribute to cumulative effects on these species.
3.3 SOCIAL ENVIRONMENT
3.3.1- Recreation and Public Safety
3.3.1.1 Recreation consequences
The analysis of recreation consequences appears here in its entirety.
Alternative 1 - Proposed Action
Implementation of this alternative would intermittently disrupt recreation activities. Traffic delays may occur on Maple Springs Road, Trabuco Creek Road, and Holy Jim Trail during project implementation. An exact estimate of the time delay is unknown at
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this time, but it would be likely to include intermittent delays over the course of about a week for the roads, and up to several weeks for Holy Jim Trail. Recreationists would have access to other trails in Trabuco Canyon and to recreation residence cabins in Trabuco and Holy Jim tracts during the demolition work. Implementation of this alternative would be expected to reduce safety hazards to forest visitors by reducing opportunities for visitors to fall or jump from dam structures. This would be a minor contribution to cumulative effects on recreation opportunity, as other temporary closures for weather or safety are routinely implemented on Forest roads and trails.
Alternative 2 - No Action
The no action alternative would have no effect on recreation opportunities.
3.3.1.2 Emergency access/firefighting resources
The analysis of emergency access and firefighting resources appears here in its entirety.
Alternative 1 - Proposed Action
Road access would still be available for emergency vehicles. The project would comply with Forest rules and restrictions regarding management of fire ignition sources. Implementation of the project will affect the stream structure; however streams would still have pools that may be used for suppression of small wildfires. The proposed action would not contribute to cumulative effects on fire suppression resources.
Alternative 2 - No Action
The no action alternative would have no effect on emergency access or firefighting resources.
3.3.1.3 – Scenic integrity consequences
The analysis of scenic integrity consequences appears here in its entirety. Current scenic integrity objectives are “High” for Silverado, Holy Jim, and San Juan Creeks. A Scenic Integrity Objective of “High” indicates that the landscape appears unaltered. The desired condition for all of the streams in the project area (see EA sections 1.4.1 and 1.4.2) is to maintain and emphasize natural-appearing (vs. man-made) landscapes (Cleveland National Forest Land Management Plan 2006).
Alternative 1 - Proposed Action
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The dams were not found to be historically significant or eligible for the National Register (see section 3.3.2 below) so are not considered to be contributing to cultural or scenic values in the area. Holy Jim and San Juan Creek contain recreation residence tracts. All of the canyons have some existing infrastructure including roads, concrete fords, gabions, retaining walls, and riprap that reinforce the roads and/or road crossings. Removing dams would implement Forest goal 5.2- “improve riparian conditions” (USDA Forest Service 2006) and would be consistent with scenic integrity objectives for the project area. Due the small scale of the proposed project, which would affect approximately four acres, the project would slightly improve scenic integrity in the project area by restoring streams to a more natural condition. The project would slightly reduce cumulative effects on scenic integrity, as it would reduce the footprint of man- made structures within the project watersheds.
Alternative 2- No Action
Implementing this alternative would have no effects on scenic integrity objectives.
3.3.2 Cultural resources
Alternative 1 - Proposed Action
An analysis of the potential for effects to historic properties associated with the ground disturbing component of the proposed project is contained in the Regional Programmatic Agreement Compliance document prepared in support of the proposed project by the CNF Heritage Program Manager (HPM). An analysis of the potential for effects to historic properties associated with the physical demolition and removal of the dams is contained in the historic properties evaluation and determination of National Register eligibility report that was contracted to and is being prepared by the Heritage Stewardship Group (HSG), a Forest Service Enterprise Unit that specializes in historic preservation and cultural resource management on National Forest lands. These analyses and determinations of the potential for effect to historic properties were prepared in accord with Section 106 of the National Historic Preservation Act (NHPA), its implementing guidance contained in 36 CFR 800, and the Programmatic Agreement among the USDA Forest Service, Pacific Southwest Region (Region 5), California State Historic Preservation Officer, Nevada State Preservation Officer, and the Advisory Council on Historic Preservation Regarding the Process for Compliance with Section 106 of the National Historic Preservation Act for Management of Historic Properties by the National Forests of the Pacific Southwest Region (Regional Programmatic Agreement).
An evaluation and Determination of Eligibility (DOE) report has been prepared by the HSG architectural historian, utilizing data and documentation provided by the CNF HPM, Orange County Archives, Orange County Historical Society, Cal Fire, and Orange County Fire Authority in addition to using secondary literature (newspapers, etc.). The
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HSG architectural historian meets the Secretary of the Interior’s Professional Qualifications Standards per 36 CFR 61. Project fieldwork and data collection was completed by Forest Heritage Program and Resources staff in March 2013. Fieldwork included photography and documentation of the physical aspects of each of the 108 known check dams and the surrounding landscape. Preliminary evaluation and analysis resulted in a determination that the three intact dams in Trabuco Creek, although of some local interest and importance, do not meet any of the four National Register criteria for significant Historic Properties. SHPO has indicated that the remainder of the dams would likely not be considered historic by association, as they are in very poor condition, are lacking in integrity, and/or have been removed completely. The evaluation has been finalized and submitted to SHPO for concurrence. SHPO concurrence is expected within 30 days and will be obtained prior to any decision regarding the proposed demolition of the dams, in accordance with Section 106 of the NHPA and the RPA. Should the dams be determined to be eligible for listing on the National Register, appropriate mitigation for the adverse effect associated with their demolition will be developed and implemented in consultation with SHPO.
Based on the results of the analysis of the potential for effects to historic properties associated with the ground disturbing component of the proposed project, there would be no effect to historic properties associated with the implementation of the proposed project, and it is exempt from further heritage review or consultation as it qualifies as a Class II Screened Exemption under the stipulations of the RPA. In the event that the scope or design of the proposed project were to be changed, analysis of the changes and any associated potential for effects to historic properties would be conducted by the Forest Heritage Program Manager prior to implementation of those changes. If any previously unrecorded cultural resources were inadvertently discovered during implementation of the proposed project, all project-related activities in the vicinity of the discovery would cease, appropriate steps to secure and protect the discovery would be taken, the Forest Heritage Program Manager would be notified, and the process defined in Stipulation V of the Programmatic Agreement would be implemented.
Any identification of human remains during the implementation of the proposed project would result in the implementation of the same procedures describe above, as well as the implementation of the procedures for the protection and determination of the proper disposition of human remains stipulated in the Native American Graves Protection and Repatriation Act (NAGPRA). Suspended project activities in the vicinity of the inadvertent discovery of any cultural material or human remains would be resumed only with the written permission of the CNF HPM.
Alternative 2- No Action
Direct, indirect, and cumulative effects to cultural/heritage resources: This alternative would have no effect to historic properties, and no Section 106 review or SHPO consultation would be required prior to implementation of this alternative.
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CHAPTER 4 Persons, Groups, Organizations and Agencies Consulted
List of preparers
Michelle Bearmar, Geotechnical Engineer. Southern Province Forests.
Heather Dyer, Forest Fisheries Biologist. Cleveland National Forest.
Nick Ettema, Fisheries Biologist. Inyo National Forest. (now with Federal Energy Commission, Washington DC).
Emily Fudge, Forest Hydrologist. Cleveland National Forest.
Steve Harvey, Heritage Resource Officer. Cleveland National Forest.
Chad Hermandorfer, Hydrologist. TEAMS Enterprise group.
Mike McCorison, Air Quality Specialist. Southern Province Forests.
Susan Roder, Heritage Assistant. Cleveland National Forest.
Kirsten Winter, Forest Biologist. Cleveland National Forest.
Agencies consulted
California Department of Fish and Wildlife
National Marine Fisheries Service
State Office of Historic Preservation
State Water Quality Board
US Army Corp of Engineers
US Fish and Wildlife Service
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CHAPTER 5 References
California Department of Fish and Wildlife. 2013. Fish passage website. http://www.calfish.org/
Executive Order 11988 - Floodplain Management.1977. 42FR 26971, 3CFR, 1977 Comp, p. 117.
Federal Emergency Management Agency. 2013. FEMA Map Service Center. https://msc.fema.gov/webapp/wcs/stores/servlet/FemaWelcomeView?storeId=10001&cat alogId=10001&langId=-1
Holy Jim and Trabuco Cabins Facebook page. Accessed Jan 2013. https://www.facebook.com/pages/Trabuco-and-Holy-Jim-Cabins/334980809907659
Hoffman, R. and J. Dunham. 2007. Fish movement ecology in high-gradient headwater streams: Its relevance to fish passage restoration through stream culvert barriers. USDI US Geological Survey report. Available online at http://fresc.usgs.gov/products/papers/1710_Hoffman.pdf
National Marine Fisheries Service. 2011. Southern California Steelhead Recovery Plan. Southwest Region, Protected Resources Division, Long Beach, California. 563 pages. http://www.nmfs.noaa.gov/pr/recovery/plans.htm
Newland, James D. 2008. Cleveland National Forest (Images of America: California). 128 pp.
Orange County Fish and Game Commission. 1982. Orange County Fish Dams. Interim Operating Plan, 1982 Fishing Season. Cleveland National Forest files.
USDA Forest Service. 2000. Water Quality Management for Forest System Lands in California, Best Management Practices, Pacific Southwest Region, Vallejo, California
USACE and County of Orange. 2002. San Juan Creek Watershed Management Plan
USDA Soil Conservation Service, Forest Service, and Univ. of California Agricultural Experiment Station 1978. Soil Survey of Orange County and Western Part of Riverside County, California.
USDA Forest Service. Forest Service Handbook 7709.56b, Chapter 7 Section 7.4 (1) (2).
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USDA Forest Service. Land Management Plan. 2006. Southern California Forests. R5-MB-075.
USDA Forest Service. 2011. Environmental Assessment. Trabuco Aquatic Organism Passage Restoration. Trabuco Ranger District, Cleveland National Forest, Orange and Riverside Counties, California. Cleveland National Forest files.
USDA Forest Service Biological Assessment, 2013a. Trabuco District Dam Removal Project. Cleveland National Forest files.
USDA Forest Service. 2013b. Biological Evaluation. Trabuco District Dam Removal Project. Cleveland National Forest files.
USDA Forest Service 2013c. Heritage Resources Report. Trabuco District Dam Removal Project. Cleveland National Forest files.
USDA Forest Service. 2013d. Hydrology Report. Trabuco District Dam Removal Project. Cleveland National Forest files.
USDA Forest Service. 2013e. Management Indicator Species Report. Trabuco District Dam Removal Project. Cleveland National Forest files.
USDA Forest Service. 2013f. Migratory Bird Report. Trabuco District Dam Removal Project. Cleveland National Forest files.
USDA Forest Service. 2013g. Noxious Weed Risk Assessment. Trabuco District Dam Removal Project. Cleveland National Forest files.
USDA Forest Service. 2014. §106 Determination of Eligibility for the National Registerof Historic Places- Cleveland National Forest Fish Check Dams. Prepared by Rachel Kline, Architectural Historian, Heritage Stewardship Group (Enterprise Unit).
USDA Soil Conservation Service. 1978. Soil Survey of Orange County and Western Part of Riverside County, California. 149 pages plus maps.
USDI Fish and Wildlife Service. 2014. Formal Section 7 Consultation for the Removal of Rock Dams within San Juan Creek, Orange County, California.
US Dept of Labor, Bureau of Labor Statistics. 2013. Consumer Price Index Inflation Calculator. http://www.bls.gov/data/inflation_calculator.htm
US Geological Survey. 2013. (USGS webpage - http://ga.water.usgs.gov/edu/100yearflood.html )
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Appendix A: Photographs of Typical Dams
Figure 1: Silverado Creek - example of larger intact dam, showing undermining.
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Figure 2: Holy Jim Creek – example of larger intact dam.
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Figure 3: San Juan Creek – example of larger intact dam.
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Appendix B: Response to Comments Trabuco District Dam Removal
The Forest Service has documented, analyzed, and responded to the public comments received during the scoping and comment periods for the Trabuco District Dam Removal Project. This appendix summarizes the comments that were received during the scoping and comment periods and provides the agency’s response to those comments. These responses comply with 40 CFR 1503.4, Response to Comments, of the National Environmental Policy Act (NEPA) regulations.
Comment Analysis and Response
Public comments submitted were documented, compiled, categorized, and analyzed in order to capture all viewpoints and concerns submitted during the official scoping and comment periods. Information from letters, emails, and other sources are all included in this response to comments. The response to comments helps the USDA Forest Service clarify, adjust, or incorporate additional technical information into the EA.
Specialists read all public responses and identified separate comments within them that relate to a particular concern, resource consideration, and/or requested management action. Specialists categorized each comment into a subject area that is specifically relevant to this project. After categorizing comments, responses were written to address the public input that was received. The interdisciplinary team provided any recommendations for improvement to the proposed action to the Trabuco District Ranger for review, consideration, and action. In general, the agency responds in the following five basic ways to substantive public comments, as prescribed in 40 CFR 1503.4:
1. Modifying alternatives. 2. Developing and analyzing alternatives not initially given consideration. 3. Supplementing, improving, or modifying the analysis documented in the EA. 4. Making factual corrections. 5. Explaining why the comments do not need further Forest Service response.
This response document is organized based on the categorization of comments into subject areas, as described above. Therefore, the organization of this appendix does not directly match the organization of the EA and is instead more closely tied to the concerns that the public shared during the scoping period with the proposed action. Comments that may have fit into several categories were addressed only once.
It is important to point out that the consideration of public comments is not a vote- counting process in which the project outcome is determined by the majority opinion. More importantly, it is the appropriateness, specificity, and factual accuracy of comment content that serves to provide the basis for modifications to planning documents and
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decisions. Further, because respondents are self-selected, they do not constitute a random or representative public sample. NEPA encourages all interested parties to submit comments as often as they wish. Every substantive comment and suggestion has value, whether expressed by one respondent or many. All input is read and evaluated, and the analysis team attempts to capture all relevant public concerns in the analysis process.
Per the legal notice, the 30 day period to comment on the Trabuco District Dam Removal Environmental Assessment began September 24, 2013, and ended October 24, 2013. Eleven comments were received by email, two comments were received by USPO mail, and no comments received by telephone during this time period. Several comments were received after the close of the comment period and are not part of the official record, although the Forest agreed to consider late comments.
1. Cost and financial concerns:
1.1 Commenters stated that the cost of removing the dams was too high and not a good use of funding.
Response to 1.1: See alternatives comparison chart, Section 2.4 of Environmental Assessment, which displays the cost of the various alternatives. See also response to comment 4.8, which discusses the risks of no action. Please note that the Forest is seeking funds that are specifically allocated for removal of fish barriers for this project; these funds, if received, may not be used for other types of projects.
1.2 Purpose and need does not justify the proposed action
Response to 1.2: See revised purpose and need section in Section 1.3 of Environmental Assessment which provides additional detail regarding the rationale for the project.
1.3 How can cabin owners seek compensation if cabins are damaged by project work or subsequent effects.
Response to 1.3 - If cabin owners believe they can show that their property has been damaged due to a Forest Service action, they may file a claim for recovery of damages.
2. Historic concerns:
2.1 The rock dams have historic value and should be preserved.
Response to 2.1- The Trabuco District Dams are a series of check dams placed intermittently within Trabuco Creek, Holy Jim Creek, San Juan Creek, and Silverado
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Creek on the Trabuco Ranger District of the CNF. The dams are made of rock and mortar. They were constructed by Orange County in the 1940s as part of a fish stocking project, in which the County constructed check dams for an approximately 10 year period. The original objectives of the program were to enhance local fishing potential, conserve water and wildlife, and provide water for fire protection. The program boomed during the 1950s and 1960s by creating popular fishing areas. The program began to wane during the 1970s, which led to the deterioration and subsequent removal of some of the dams. Of the approximately 108 original dams, 81 are still intact to the point where they need to be demolished to allow for fish passage. These 81 dams are located along Trabuco Creek, Holy Jim Creek, Silverado Creek, and San Juan Creek. Due to the potential eligibility of the dams for nomination to the National Register due to their age (>50 years), association with local history, and the potential adverse effect of the proposed demolition, the dams were recommended for a Determination of Eligibility (DOE) evaluation and associated SHPO consultation prior to any decision regarding the proposed demolition, in accord with Section 106 of the National Historic Preservation Act (NHPA) and the Regional Programmatic Agreement (RPA 2013).
An evaluation and draft DOE report for the three intact dams in Trabuco Creek was prepared by the Heritage Stewardship Group (HSG), a U.S. Forest Service Enterprise Business Unit specializing in historic preservation and cultural resource management. To develop the DOE, HSG’s Architectural Historian utilized data and documentation provided by the CNF Heritage Program, Trabuco Ranger District, Orange County Archives, Orange County Historical Society, Cal Fire, and Orange County Fire Authority in addition to using secondary literature. Project fieldwork was completed by Forest Heritage Program and Resources staff in March 2013. Fieldwork included photography and documentation of the physical aspects of all of the 108 known check dams and the surrounding landscape. The evaluation was completed by an architectural historian who meets the Secretary of the Interior’s Professional Qualifications Standards per 36 CFR 61. The draft report is in the process of being rewritten to include documentation (DPR Archaeological Site forms), evaluation and DOE for all of the 108 known dams that may potentially be included in the demolition project, rather than just the three primary intact dams in Trabuco Creek, based on verbal consultation with SHPO. The projected completion date for the final draft is January 2014. The original evaluation resulted in a preliminary determination that the three intact dams, although of some local interest and importance, do not meet any of the four National Register criteria for significant Historic Properties, according to the Architectural Historian that conducted the evaluation. SHPO verbally indicated that it could concur with that determination, and that the remainder of the dams would not be considered historic by association, as they are in very poor condition and are lacking in integrity, or have been removed completely. Once the draft evaluation has been provided for public comment it will be finalized and submitted to SHPO for concurrence, prior to any decision regarding the proposed demolition of the dams, in accord with Section 106 of the NHPA and the RPA.
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3. Scenic values concerns.
3.1 Dams and associated “waterfalls” are scenic and should be preserved. Removal of the dams will impair the scenic integrity of the area. Response to 3.1– Please see expanded discussion of Scenery Objectives, Section 3.3 of EA. The CNF Land Management Plan (2006) specifies a Scenic Integrity Objective level of “High” for the entire project area, a classification that “provides for conditions where human activities are not visually evident.” In other words, man-made artifacts like dams are considered to detract from, rather than add to, the area’s scenic integrity.
3.2 Leaving rock materials in place after dam demolition will decrease scenic value of area; waste materials will be left in unsightly mounds Response to 3.2. Please see additional discussion, Section 3.3 of EA. Please note that all of the streams currently have roads, road crossings, rip-rap, gabions, retaining walls, remnants of failed dams, and other types of materials present in and adjacent to stream channels. Due to the dynamic nature of these streams, rock and concrete fragments resulting from dam demolition will be transported downstream and out of the project area over time, during rainfall events.
3.3 Defunct installations such as these dams detract from the forest experience and should be removed. Response to 3.3 – Thank you for this comment, which supports the information presented in the Environmental Assessment.
3.4 Holy Jim Canyon is not a Wilderness so it should not be restored to a more natural condition. Response to 3.4 - Please note that the Forest Land Management Plan states that Scenic Integrity Objectives for Trabuco/Holy Jim, San Juan, and Silverado are “high”; and Ortega Highway Corridor (San Juan) is a Scenic Byway. A Scenic Integrity Objective of “High” is the equivalent of a landscape that appears unaltered. See Scenic Integrity Objectives map in Forest Plan. The landscape strategy (Land Management Plan Part 2, page 105) includes direction to “Restore landscapes to reduce visual effects of management activities and nonconforming features”. Appendix E provides direction for Riparian Conservation Areas, and states that the Forest will allow “only those actions that maintain or improve long-term aquatic ecosystem health.” Please see also the discussion of scenic values, Section 3.3 of EA.
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4. Hydrological concerns: 4.1 Removal of dams will increase the extent of the floodplain in and downstream of project area Response to 4.1 – The dams were not constructed for flood control. At a 6th field watershed HUC scale, they have not changed the duration, timing, or water inundation levels during past major flood events such as the 50-100 year floods of 1938 and 1969. Therefore, the 100-year floodplain width that existed prior to dam construction is the same width that occurs today 40-70 years after the structures were initially constructed. Although the extent and function of the 100-year floodplains are not affected by this project, due to the interest expressed by several commenters, additional information about floodplain mapping is provided here.
Floodplains are the relatively flat lowland that borders a river, usually dry but subject to flooding. Floodplain soils actually are former flood deposits (USGS webpage, 2013).
Existing FEMA flood mapping for San Juan, Silverado, and Trabuco Creeks covers areas just downstream of the Cleveland National Forest boundary (FEMA Map Service Center, 2013) The FEMA mapping shows that the floodplains in these streams overlap with two soil types- Riverwash, and Soboba cobbly loam. The USDA Soil Conservation Service has mapped soils in this area (USDA Soil Conservation Service 1978) and describes these soil types as follows:
Riverwash – Riverwash consists of areas of unconsolidated alluvium, generally stratified and varying widely in texture, recently deposited by intermittent streams, and subject to frequent changes through stream overflow.
Soboba series - The Soboba series consists of excessively drained soils on floodplains and alluvial fans.
Since FEMA maps were not available for Forest lands, the Forest followed the direction in Executive Order 11988 on Floodplain Management (1977). This order states that “if such maps are not available, the agency shall make a determination of the location of the floodplain based on the best available information.” On National Forest System lands, floodplain soils (Riverwash and Soboba series) are present along the stream channels in Silverado, Trabuco, Holy Jim and San Juan Canyons. A map of the extent of floodplain soils for
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Holy Jim and Trabuco Creeks is provided in Figure 1.
Figure 1. Extent of floodplain soils mapped by the USDA Soil Conservation Service in 1978.
Figure 1 indicates that the roads and recreational residence in both Trabuco and Holy Jim Canyons were constructed within the currently mapped 100 year flood plain. Removal of the dams will not change this fact.
4.2 Request for document that mapped 100-year floodplain Response to 4.2 – No formal mapping of the 100-year floodplain has been completed by the Federal Emergency Management Agency (FEMA) on
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National Forest System lands within the project areas. However, the USDA Soil Service mapped the floodplain soils in each of the project area canyons in 1978. The extent of these mapped soils provides an accurate depiction of the present day 100-year floodplain due to the constraints of the canyon geomorphology. See response 4.1 for more detail on this subject.
4.3 Removal of dams will increase flood risk to cabins/historic cabins, roads, trails, trees, retaining walls.
Response to 4.3 – The dams, built by Orange County between the 1940s and mid-1970s, were not built to provide for flood protection and were never operated to provide for flood control. Each dam had a wooden gate that was placed in the center of the dam each spring to retain water through the summer. Gates were then removed in the fall to allow water to flow through the dam during winter storms. Therefore, removal of dams would not impact the risk to future flooding during major storm events. Five of the dams in Holy Jim Creek were built or rebuilt without central gates; these dams have filled with sediment and do not store water. Figure 2 shows flood damage in Trabuco Canyon from the winter of 1937-1938. There have been other flood events that have damaged infrastructure during the time after the dams were constructed, primarily in 1969 when 6 cabins washed away and another 5 cabins were undermined or damaged. These canyons are highly dynamic and flashy systems that developed naturally through episodic flooding events over time.
Figure 2. Historical photo from the winter of 1937 showing flood damage in Trabuco Canyon after a significant winter rainfall event. Photo courtesy of James Newland.
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A higher risk of increased flooding would occur if the dams are left in place. Over time, unmaintained dams have the potential to fail. This failure could cause stream channel avulsion during higher flows which could potentially damage established infrastructure. 4.4 Removal of dams will increase erosion risks
Response to 4.4 – In the short term, removal of the dams would promote increased erosion of the material that has been trapped behind the dams. Because of this, we would remove a set of dams in areas with higher values at risk (Holy Jim Canyon) systematically and let the material work itself through the system before another set number of dams would be removed. The removal would take at least 3 years depending on the reworking of the stream due to precipitation over that time. The alternative to systematically removing the dams would be to let them fail naturally. There is no intention by Orange County to maintain these dams in the future. Because of this they will inevitably fail. When this happens it is probable the trapped material would be released downstream at once. Depending on the magnitude of the storm and failure of the dams, allowing this to happen could have significant impacts to downstream infrastructure including cabins and roads.
4.5 Removal of dams will release excessive/dangerous amounts of sediment Response to 4.5 – See response to 4.4.
4.6 Removal of dams will cause catastrophic flows of water and sediment Response to 4.6 – See response to 4.4
4.7 Removal of dams will impact the performance of nearby wells needed for domestic water supply and firefighting Response to 4.7 – Wells used by residential tract residents in Holy Jim Canyon are solely groundwater wells. There are no surface water intakes that would be affected by the anticipated short term sediment release. Groundwater recharge in these areas could only be impacted by drought and/or water diversions. To our knowledge, there are no significant upstream diversions impacting groundwater recharge in the Holy Jim area. As for firefighting, we have identified reliable water source points in each of the Canyons should water be needed. The plan does not include any of the pools created by the existing dams.
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4.8 Hydrology report underestimates the nature of storms in SoCal, specifically El Nino events; commenter implies that cabin owners will be at increased risk during these storms if dams are removed.
Response to 4.8 – Holy Jim and Trabuco Canyons are highly dynamic and flashy systems that developed through episodic flooding events over time. This is evidenced by the alluvial fan where the cabins in lower Holy Jim are located. The reason that this area is flatter and wider than the rest of the Holy Jim Canyon is because the gradient drops once the channel leaves the confined section of Holy Jim and enters the recreational residence area. In less confined areas of a channel, stream velocity and carrying capacity decreases, resulting in sediment deposition. It is natural for the channel to drop material here and subsequently migrate back and forth across the channel bottom as evidenced in both Holy Jim and Trabuco during past flooding events such as in 1937, 1965, 1969, 1998, 2008, and 2010.
The stream channel through the cabin area has been channelized in the past in an attempt to protect the cabins in the area. This channelization creates more energy downstream of the cabins and contributes to the damage that occurs in Trabuco Canyon, specifically Trabuco Canyon Road after significant storm events. Further, the dams were never intended to protect the cabins from flooding. This is evidenced by a video provided by recreational residence owner Milligan where the water is completely overtopping a dam just above the cabins. If it was a flood control structure the water would be captured and released into the system at a later time.
The bottom line, from a hydrology and geomorphology perspective, is that the recreational residence tracts in Holy Jim are located in an area that over geologic time is extremely dynamic. The current dams are not protecting cabins from flooding or stream channel avulsion. The bigger risk is the fact that these aging non-flood control dams, of which are not being maintained and will not be maintained in the future, will fail someday. When that happens the material that has been trapped upstream of the cabins would be released into the system with potentially damaging effects. This represents a much larger risk to the cabins and downstream infrastructure than if the Forest Service systematically removes them using sound scientific and engineering principles.
4.9 Removing dams will create a downstream Venturi effect that will increase scouring and erosion, endanger cabins and roads, trails, trees Response to 4.9 – The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. Because this project does not involve fluid in a pipe, the Venturi principle is not valid for this
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project. The dams funnel and channel stream flow, creating a scouring effect downstream. Removal of the dams will decrease this scouring action.
4.10 Photos from 1969 demonstrate destructive potential of floods- hydrology report needs to consider this.
Response to 4.10 – The photos provided by Mr. Milligan illustrate the dynamic nature of the stream systems in the Santa Ana Mountains. When significant precipitation occurs, the streams become flashy, dynamic and dangerous. The photos illustrate that infrastructure becomes vulnerable and that the existing dams do not provide any protection when heavy precipitation and subsequent flooding occurs. A mention of the 1969 event was updated in the hydrology specialist report.
4.11 Some of the cabins are historic. They will be at risk and may be destroyed if dams are removed.
Response to 4.11 – The dams, built by Orange County between the 1940s and mid-1970s, were not built to provide for flood control and were never operated to provide for flood control. There is currently no flood control for any of the cabins in the Holy Jim, Trabuco, or San Juan cabin tract areas. Naturally, these streams are highly dynamic systems with the potential to produce large floods that could damage local infrastructure as evidenced by past events. The removal of dams will not change this risk into the future. Forest records indicate that approximately 21 cabins in the Holy Jim and Trabuco tracts have been lost to floods since the 1940’s - approximately 15 cabins in the 1937/1938 floods, and 6 in the 1969 flood. There is a high baseline risk of flooding in this area that is not influenced or affected by the proposed action.
5 Biological concerns:
5.1 Removal of dams may harm Sticky Dudleya and Ocellated Humboldt Lily plants; these should be salvaged from work areas
Response to 5.1. The proposed action has been revised to include salvage and replanting of these species, see Section 2.1.1 of EA, General Resource Protection measures, item 7.
5.2 Removal of dams will not benefit steelhead as they are not currently present; steelhead will not recolonize these streams – impossible to create a migration route for them
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Response to 5.2. The impediments created by multiple fish-passage barriers within each creek are a concern addressed by the Southern California Steelhead Recovery Plan (NMFS 2011). We fully recognize that restoring suitable habitat conditions for steelhead migration, spawning, and rearing of young will require multiple management actions by several agencies over many years. The physical modification of road crossings and other barriers has been listed by NMFS as a critical recovery action for this geographic area. NMFS has indicated a plan to address impassable barriers in the downstream portions of the creeks. The Forest Service’s plan is to implement this recovery action within our own boundaries, as funding permits, which supports both the recovery plan as well as our management plan. Additional discussion of this concern appears in section 3.2.1 of the EA.
5.3 No evidence that steelhead ever occupied Trabuco Creek – trout there were planted.
Reponse to 5.3. The National Marine Fisheries Service performed an extensive review of Southern California Steelhead for the 2012 Recovery Plan in which they determined that tributaries within the Southern California Steelhead Recovery Planning Area, including the San Juan Creek/Arroyo Trabuco watershed, were historically occupied and have the potential to support steelhead in the future once man-made barriers are removed. Additional discussion of this concern appears in section 3.2.1 of the EA.
5.4 Removal of dams will not benefit steelhead unless downstream barriers are also removed (Four Trabuco Ck road crossings, et al.) implementation of dam removal should be incremental, should be delayed and implemented only after downstream barriers are removed.
Response to 5.4. The Southern California Steelhead Recovery Planning Area includes portions of the coastal watersheds that are currently inaccessible to steelhead due to man-made barriers. The National Marine Fisheries Service has identified physical modification of barriers such as road crossings, highways, and railways as a critical recovery action in the Recovery Plan (NMFS 2011). Modification of these fish passage barriers is a necessary first step to providing functional habitat to steelhead and other native fish. In recognition of this, the Forest Service is working proactively to remove the barriers from our lands as funding is available. Additional discussion of this concern appears in section 3.2.1 of the EA.
5.5 Trabuco/Holy Jim do not have enough water to support a persistent resident population of steelhead .
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Response to 5.5. The Southern California Steelhead Recovery Planning Area (NMFS 2011) includes portions of the coastal watersheds that are only seasonally accessible to migrating steelhead. While it is true that due to relatively low average rainfall in the region many of the drainages are seasonally dry or can have extensive dry portions, steelhead will attempt to move upstream into upper portions of a stream when water flow conditions are favorable for migration. Therefore, we will work to improve creek habitat on the Forest in preparation for the years when conditions support movement to and use of the habitat by steelhead. Additional discussion of this concern appears in section 3.2.1 of the EA.
5.6 Forest vegetation is already changing due to drier climate (eg death of alder trees), drier conditions will make it difficult for steelhead to access Trabuco Ck. Response to 5.6. The Mediterranean climate of southern California has long dry summers, and brief winters with short, intense storms. Steelhead have been a part of this ecosystem for a very long time and have adapted to the “flashy” hydrologic conditions. While climate change predictions suggest storm and drought cycles may be amplified in the future, steelhead will have opportunities to migrate upstream in tributaries when the flow conditions are favorable (NMFS 2011). Additionally, the ability of the species to switch between multiple life-history strategies (freshwater residency and/or anadromous migration) will be an important adaptive response to changing, highly variable environmental conditions. Additional discussion of this concern appears in section 3.2.1 of the EA.
5.7 Removal of dams in Holy Jim/Trabuco will not benefit steelhead or arroyo toad.
Response to 5.7. Over time, the dam removal will benefit both of these species as release of sand and gravel from the dams will improve the condition of spawning or breeding habitat for these species downstream of the project area, as well as improving aquatic organism passage within and upstream of the project area. Please see section 3.2.2 of EA.
5.8 Removal of dams will not benefit arroyo chub.
Removal of dams will substantially benefit arroyo chub as their populations are currently fragmented by the dams. Please see sections 3.2.2 of EA and response to comment 5.15.
5.9 Arroyo chubs and pond turtles are not present in Trabuco/Holy Jim Creek.
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Response to 5.9. Forest records and range maps for these species indicate that there is occupied or potential habitat for these species in Trabuco and Holy Jim Creeks, so these species must be considered in the project analysis.
5.10 There are no horned lizards in Trabuco Canyon. Response to 5.9. Forest records and range maps for these species indicate that there is occupied or potential habitat for these species in Trabuco and Holy Jim Creeks, so these species must be considered in the project analysis.
5.11 Removal of dams will harm wildlife species such as migratory birds.
Response to 5.11. The project may result in a short term disturbance to migratory birds as described in the EA. Effects on migratory birds will be minimized by completing project work in the fall when few birds are nesting. Migratory birds will experience a long-term benefit from the project as the streamside habitat recovers after removal of dams. Please see section 3.2.4 of EA.
5.12 Fish ladders should be installed to allow for fish movement. Response to 5.12. Please see the analysis of Alternative 3, in section 2.3 of EA. Fish ladders are not feasible because they do not meet the purpose and need of the project, and they are extremely expensive. 5.13 Special use permittees (rec cabin owners) protect the native wildlife such as newts, snakes, lizards, and have built small dams to preserve pool habitat for California tree frog tadpoles. Response to 5.13. The Forest appreciates the efforts of recreation cabin owners to protect wildlife. However, dam construction is not allowed by the recreation cabin special use permits and requires state and federal permits. 5.14 Dams are a refuge for wildlife including snakes, lizards, frogs and newts.
Response to 5.14. The stream will continue to have pools and rocky banks after dam removal, which will provide habitat and refuges for these species. Please see Section 3.1.2 of EA for further information.
5.15 Trout, fish, salamanders do not need to move up and downstream to maintain populations. Response to 5.15 - Fish and other aquatic wildlife do need to travel up and downstream to seek out suitable mates, breeding habitat, and feeding habitat. As summarized in the EA, Section 3.2.2, and in Hoffman (2007); “Movement is an essential mechanism by which mobile animals acquire the
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resources necessary for the successful completion of their life-cycles (Greenwood and Swingland 1983; Dingle 1996). It also plays a crucial role in how animals are distributed across the landscape and the persistence of populations and species (Ricklefs 1990;Fausch et al. 2006).
6 Hazardous Materials concerns:
6.1 Removal of dams will release arsenic and mercury that were used in Holy Jim placer mine operations.
Response to 6.1: The Hydrology Report discusses in detail the beneficial uses and State of California 303d listing status of waters near the project area. Holy Jim Canyon is not, nor has it been, listed by the state for any water quality issues related to arsenic or mercury. Although the Forest does not have records of historic mining, some small scale mine tailings have been observed, which indicates that mining could have occurred at some time. However, because there have not been elevated mercury or arsenic levels in Holy Jim Canyon historically (no historic 303d listing), there is no evidence that there would be elevated levels of arsenic or mercury resulting from project implementation in the near future.
6.2 – Commenter states that protective measures such as spill prevention will not be adhered to.
Response to 6.2: Project Design Features, including best management practices (BMPs), site-specific mitigations, and Forest Plan Standards and Guidelines are an integral part of implementing the project.
BMPs have been designed to protect and restore watershed resources. Implementation of BMPs ensures adherence to the Federal Clean Water Act. All federal agencies must comply with the provisions of the Clean Water Act, which regulates forest management activities near federal waters and riparian areas. Additionally, the 2005 Cleveland Forest Plan directs water quality to be maintained and improved through the use of state certified and Environmental Protection Agency (EPA)-approved BMPs. The design features and BMPs associated with the proposed action ensure that Sections 208 and 319 of the Federal Clean Water Act (PL 92-500) and the guidelines established by the Santa Ana and San Diego Regional Water Quality Control Boards (California Regional Water Quality Control Board, Santa Ana River Basin, 2008, California Regional Water Quality Control Board San Diego, 1994, amended 2011) are met.
Spill prevention and containment measures are required to be in compliance with the National Best Management Practices (BMPs) AqEco-2, which states “…Promptly
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install and appropriately maintain spill prevention and containment measures…” (USDA, 2012). The EA discusses water quality (chemical contamination) on page 28- 29 and states that BMPs would be implemented as part of the project specifications.
Overall, to be in compliance with the Federal Clean Water Act, BMP implementation including spill prevention is mandatory.
7 Fire management issues:
7.1 – Removal of dams will prevent use of stream pools for firefighting efforts as pools will fill with sediment
Response to 7.1- The dams have central gaps or openings where gates were once placed. The gates have not been in use for 20 years or more, and the dams do not store water. Some dams have plunge pools downstream; after dam removal pool locations may shift but pools will still be present and will be available for emergency firefighting. In general other water sources such as water tanks, or aerial drops of water from nearby lakes, are the preferred sources of water for firefighting. See Hydrology report and section 3.1.2 of EA for further details.
8 Safety concerns:
8.1 – Concern that use of explosives to demolish dams will damage cabins and adjacent roads in Holy Jim/Trabuco Creek. What actions will be taken to protect cabins and facilities?
Response to 8.1 - The project includes several measures to protect cabins and facilities. See expanded description of proposed action, Section 2.1 which describes using a phased approach to allow gradual release of sediment at Holy Jim Creek, avoiding use of explosives near roads and structures at Holy Jim Creek, and preparing detailed engineering designs for demolition of dams near roads and structures.
8.2 – There are no safety hazards associated with recreational activity on and around dams.
Response to 8.2. Historically, when dams were in operation and seasonal gates were installed, there were several serious injuries associated with people jumping or diving from the dams. Since the county stopped installing the gates, these problems have decreased but there is still potential for people to climb on the dams and jump or fall from these structures. Please see section 3.3.1 of EA.
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9 General support for proposed action.
9.1 In favor of removing dams to restore natural flows and replenish beaches downstream
9.2 Supports removing dams which are useless infrastructure that encourages graffiti.
9.3 Supports removing dams to restore riparian vegetation and fauna
Response to 9.1, 9.2. 9.3 - Thank you for these comments, they support the discussion in the Environmental Assessment.
10 Other concerns:
10.1- Question about desired condition for Silverado Place (EA p. 7) – what communities are protected?
Response to 10.1 – This phrase refers to providing an open space area that is a refuge for human visitors.
10.2- Request to change the order of items in project description – p 11 and 13- move up items regarding equipment cleaning to top of list.
Response to 10.2 – This change has been made and items were re-organized for clarity, see Section 2.1.1 of Environmental Assessment
11 Comments outside the scope of current analysis or already decided by law or regulation:
11.1 Concern about the maintenance level of Trabuco Creek Road. Use funding to maintain road.
Response to 11. 1: The Forest is aware of maintenance concerns for Trabuco Creek road. This issue is beyond the scope of the current project and will be addressed in a subsequent analysis. The funding that is available for dam removal cannot be used for road maintenance, which is funded under a different authority.
11.2 When will effects of Trabuco Creek Road on stream habitat be addressed.
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Response to 11. 2: The Forest is aware of concerns about the effects of Trabuco Creek Road on stream habitat. This issue is beyond the scope of the current project and will be addressed in a subsequent analysis.
11.3 Concern about the forest’s arundo removal project and arundo piles near project area. Response to 11.3. The weed removal project was addressed under a separate Environmental Assessment, and is outside the scope of the current analysis.
11.4 Concern about water rights for cabin owners. Response to 11.4. Water rights are administered by the State of California; this concern is outside of the scope of the current analysis.
11.5 Concern about the impacts of human population growth.
Response to 11.5 - The Forest does not have the authority to regulate population growth; this concern is outside of the scope of the current analysis.
11.6 Request for additional time to submit comments.
Response to 11.6. The length of the comment period is set by the Code of Federal Regulations, which does not allow for extensions.
11.7 Removal of dams will eliminate fish stocking/fishing opportunities.
Response to 11.7. Fish stocking is under the authority of the California Department of Fish and Wildlife; they are aware of this project and support dam removal. See CDFW’s website regarding fish passage at http://www.calfish.org/
11.8 Project work should focus on San Mateo Creek. Response to 11.8. There are no dams in San Mateo Creek on National Forest System lands. San Mateo Creek is not part of the current analysis.
11.9 One commenter indicated that he should be hired under contract for the environmental analysis and dam removal work.
Response to 11.9 - Any work that is contracted is subject to competitive bidding; this is required by Federal Acquisitions Regulations.
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APPENDIX C - BEST MANAGEMENT PRACTICES
The full suite of Best Management Practices required during dam removal are listed below, as drawn from the US Forest Service National Best Management Practices for Water Quality Management on National Forest System Lands (published April 2012 as FS-990a).
Plan-1. Forest and Grassland Planning • Establish desired conditions, goals, and objectives for soil, water quality, and riparian resources that contribute to the overall sustainability of social, economic, and ecological systems in the plan area consistent with established State or national water quality goals for the plan area. • Consider the water quantity, quality, location, and timing of flows needed to provide water supplies for municipal, agricultural, commercial, and industrial uses; hydropower generation; water recreation, transportation, and spiritual uses; aesthetic appreciation; and tourism to contribute to social and economic sustainability. • Consider the water quantity, quality, location, and timing of flows needed to provide the ecological conditions to support diversity of native and desired nonnative plants and animal species in the plan area to contribute to ecological sustainability. • Include plan objectives to maintain or, where appropriate, improve or restore watershed conditions to achieve desired conditions of soil, water quality, and riparian resources. • Consider watershed characteristics, current and expected environmental conditions (including climate change), and potential effects of land uses when determining suitability of NFS lands within the planning area for various uses. • Include standards and guidelines to maintain and, where appropriate, improve over time the quality of soil, water resources, and riparian areas when implementing site-specific projects and activities. • Include monitoring questions and associated performance measures to address watershed condition and water quality goals and objectives.
Plan-2. Project Planning and Analysis • Include watershed specialists (hydrologist, soil scientist, geologist, and fish biologist) and other trained and qualified individuals on the interdisciplinary team for project planning, environmental analysis, and decisionmaking to evaluate onsite watershed characteristics and the potential environmental consequences of the proposed activity(s). • Determine water quality management objectives for the project area. • Identify water quality management desired conditions and objectives from the land management plan. • Identify and evaluate the condition of water features in the project area (e.g., streams, lakes, ponds, reservoirs, wetlands, riparian areas, springs, groundwater-dependent ecosystems, recharge areas, and floodplains). • Identify State-designated beneficial uses of waterbodies and the water quality parameters that are critical to those uses. • Identify locations of dams and diversions for municipal or irrigation water supplies, fish hatcheries, stockwater, fire protection, or other water uses within the project area. • Identify any impaired (e.g., 303[d] listed) waterbodies in the project area and associated Total Maximum Daily Load (TMDL) analyses or other restoration plans that may exist.
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• Identify threatened, endangered, or sensitive species in or near water, wetlands, and riparian areas in the project area and their habitat needs related to water quality. • Determine potential or likely direct and indirect impacts to chemical, physical, and biological water quality, and watershed condition from the proposed activity. • Always assume hydrological connections exist between groundwater and surface water in each watershed, unless it can reasonably be shown none exist in a local situation. • Consider the impacts of current and expected environmental conditions such as atmospheric deposition and climate change in the project area when analyzing effects of the proposed activities. • Evaluate sources of waterbody impairment, including water quantity, streamflows, and water quality, and the likelihood that proposed activities would contribute to current or future impairment or restoration to achieve desired watershed conditions. • Identify and delineate unstable areas in the project area. 53 • Identify soil limitations and productivity impacts of proposed activities. • Verify preliminary findings by inspecting the sites in the field. • Develop site-specific BMP prescriptions, design criteria, and mitigation measures to achieve water quality management objectives. Consult local, regional, State, or other agencies’ required or recommended BMPs that are applicable to the activity. • Consider enhanced BMPs identified in a TMDL or other watershed restoration plan to protect impaired waterbodies within the project area. • Use site evaluations, professional experience, monitoring results, and land management plan standards, guidelines, and other requirements. • Identify Federal, State, and local permits or requirements needed to implement the project. Examples include water quality standards, CWA 401 certification, CWA 402 permits (including stormwater permits), CWA 404 permits, and Coastal Zone Management Act requirements. • Plan to limit surface disturbance to the extent practicable while still achieving project objectives. • Designate specific AMZs around water features in the project area (see BMP Plan-3 [AMZ Planning]). • Design activities on or near unstable areas and sensitive soils to minimize management induced impacts. • Use local direction and requirements for prevention and control of terrestrial and aquatic invasive species. • Use suitable tools to analyze the potential for cumulative watershed effects (CWE) to occur from the additive impacts of the proposed project and past, present, and reasonably foreseeable future activities on NFS and neighboring lands within the project watersheds. • Consider the natural sensitivity or tolerance of the watershed based on geology, climate, and other relevant factors. • Consider the existing condition of the watershed and water quality as a reflection of past land management activities and natural disturbances. • Estimate the potential for adverse effects to soil, water quality, and riparian resources from current and reasonably foreseeable future activities on all lands within the watershed relative to existing watershed conditions. • Use land management plan direction; Federal, State, or local water quality standards; and other regulations to determine acceptable limits for CWE. • Modify the proposed project or activity as necessary by changing project design, location, and
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timing to reduce the potential for CWE to occur. • Consider including additional mitigation measures to reduce project effects. • Identify and implement opportunities for restoration activities to speed recovery of watershed condition before initiating additional anthropogenic disturbance in the watershed. • Coordinate and cooperate with other Federal, State, and private landowners in assessing and preventing CWE in multiple ownership watersheds. • Integrate restoration and rehabilitation needs into the project plan. • Consider water quality improvement actions identified in a TMDL or other watershed restoration plan to restore impaired waterbodies within the project area. • Identify project-specific monitoring needs. • Document site-specific BMP prescriptions, design criteria, mitigation measures, and restoration, rehabilitation, and monitoring needs in the applicable National Environmental Policy Act (NEPA) documents, design plans, contracts, permits, authorizations, and operation and maintenance plans. • Delineate all protected or excluded areas, including, for example, AMZs and waterbodies, 303(d) listed and TMDL waterbodies, and municipal supply watersheds, on the project map.
Plan-3 Streamside Management Zone (SMZ) Planning Develop site-specific BMP prescriptions for the following practices, as appropriate or when required, using State BMPs, Forest Service regional guidance, land management plan direction, BMP monitoring information, and professional judgment. • Proactively manage the AMZ to maintain or improve long-term health and sustainability of the riparian ecosystem and adjacent waterbody consistent with desired conditions, goals, and objectives in the land management plan. • Balance short-term impacts and benefits with long-term goals and desired future conditions, considering ecological structure, function, and processes, when evaluating proposed management activities in the AMZ. • Determine the width of the AMZ for waterbodies in the project area that may be affected by the proposed activities: • Evaluate the condition of aquatic and riparian habitat and beneficial riparian zone functions and their estimated response to the proposed activity in determining the need for and width of the AMZ. • Use stream class and type, channel condition, aspect, side slope steepness, precipitation and climate characteristics, soil erodibility, slope stability, groundwater features, and aquatic and riparian conditions and functions to determine appropriate AMZ widths to achieve desired conditions in the AMZ. • Include riparian vegetation within the designated AMZ and extend the AMZ to include steep slopes, highly erodible soils, or other sensitive or unstable areas. • Establish wider AMZ areas for waters with high resource value and quality. • Design and implement project activities within the AMZ to: • Avoid or minimize unacceptable impacts to riparian vegetation, groundwater recharge areas, steep slopes, highly erodible soils, or unstable areas. • Maintain or provide sufficient ground cover to encourage infiltration, avoid or minimize erosion, and to filter pollutants. • Avoid, minimize, or restore detrimental soil compaction. • Retain trees necessary for shading, bank stabilization, and as a future source of large woody debris. • Retain floodplain function. • Restore existing disturbed areas that are eroding and contributing sediment to the waterbody.
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• Mark the boundaries of the AMZ and sensitive areas like riparian areas, wetlands, and unstable areas on the ground before land disturbing activities.
AqEco-1. Aquatic Ecosystem Improvement and Restoration Planning As appropriate or when required: Use a watershed perspective and available watershed assessments when planning aquatic ecosystem improvement or restoration projects to consider how past, current and future land use patterns affect the proposed project. Recognize that inhabitants and users at the site (beaver, deer, birds, and people) may change the current ecosystem state to suit their needs. Use desired future conditions (DFC) to set project goals and objectives. o Establish DFC consistent with Forest or Grassland Plan goals and direction. o Use a reference condition approach to determine the natural potential condition of a waterbody. Favor project alternatives that correct the source of the degradation over alternatives that mitigate, or treat symptoms of, the problem. Consider the risk and consequences of treatment failure, such as the risk that design conditions could be exceeded by natural variability before the treatment measures are established, when analyzing alternatives. Consider the potential for future changes in environmental conditions, including climate change. Consider as a first priority treatment measures that are self-sustaining or that reduce requirements for future intervention. Utilize natural stabilization processes consistent with stream type and capability where practicable rather than structural methods when restoring damaged streambanks or shorelines. Prioritize sites to implement projects in a sequence within the watershed such that they will be the most effective to achieve improvement or restoration goals.
AqEco-2. Operations in Aquatic Ecosystems As appropriate or when required: Use applicable practices of BMP Plan-2 (Project Planning and Analysis) and BMP Plan-3 (SMZ Planning) when planning operations in aquatic ecosystems. Identify the various aquatic and aquatic-dependent species that live in the waterbody, SMZ or on the floodplain and their life histories to determine protection strategies, such as timing of construction, sediment management, species relocation and/or monitoring during construction. Coordinate lake, pond and wetland activities with appropriate state and federal agencies. o Incorporate CWA 404 permit requirements and other federal, state, and local permits or requirements into the project design and plan. Use suitable measures to protect the waterbody when preparing the site for construction or maintenance activities. o Clearly delineate the work zone. o Locate access and staging areas near the project site but outside of work area boundaries, SMZs, wetlands and sensitive soil areas. o Refuel and service equipment only in designated staging areas (see BMP Road- 10 (Equipment Refueling and Servicing)).
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o Develop an erosion control plan to avoid or minimize downstream impacts using measures appropriate to the site and the proposed activity (see BMP Fac-2 (Facility Construction)). o Prepare for unexpected failures of erosion control measures. o Consider needs for solid waste disposal and worksite sanitation. o Consider using small, low ground pressure equipment and/or hand labor where practicable. o Ensure all equipment operated in or adjacent to the waterbody is clean of aquatic invasive species as well as oil and grease, and is well maintained. o Use vegetable oil for heavy equipment hydraulics wherever practicable when operating in or near water. Schedule construction or maintenance operations in waterbodies to occur in the least critical periods to avoid or minimize adverse effects to sensitive aquatic and aquatic- dependent species that live in or near the waterbody. Avoid scheduling instream work during the spawning or migration seasons of resident or migratory fish and other important life history phases of sensitive species that could be affected by the project. Avoid scheduling instream work during periods that could be interrupted by high flows. Consider growing season and dormant season for vegetation when scheduling activities within or near the waterbody to minimize the period of time that the land would remain exposed, thereby reducing erosion risks and length of time when aesthetics are poor. Use suitable measures to protect the waterbody when clearing the site. o Clearly delineate the geographic limits of the area to be cleared. o Use suitable drainage measures to improve the workability of wet sites. o Avoid or minimize unacceptable damage to existing vegetation, especially plants that are stabilizing the bank of the waterbody. Use suitable measures to avoid or minimize impacts to the waterbody when implementing construction and maintenance activities. o Minimize heavy equipment entry into or crossing water as is practicable. o Conduct operations during dry periods. o Stage construction operations as needed to limit the extent of disturbed areas without installed stabilization measures. o Promptly install and appropriately maintain erosion control measures. o Promptly install and appropriately maintain spill prevention and containment measures. o Promptly rehabilitate or stabilize disturbed areas as needed following construction or maintenance activities. o Stockpile topsoil for reuse in site revegetation. o Minimize bank and riparian area excavation during construction to the extent practicable. o Keep excavated materials out of the waterbody. o Use only clean, suitable materials free of toxins and invasive species for fill. o Properly compact fills to avoid or minimize erosion. o Balance cuts and fills to minimize disposal needs. Remove all project debris from the waterbody in a manner that will cause the least disturbance. Locate suitable areas for disposal sites before beginning operations. Contour site to disperse runoff, minimize erosion, stabilize slopes and provide a favorable environment for plant growth. Use suitable species and establishment techniques to revegetate the site in compliance with local direction and requirements per FSM 2070 and FSM 2080 for vegetation ecology and prevention and control of invasive species.
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Use suitable measures to divert or partition channelized flow around the site or dewater the site as needed to the extent practicable. Remove aquatic organisms from the construction area prior to dewatering and prevent organisms from returning to the site during construction. Return clean flows to channel or waterbody downstream of the activity Restore flows to their natural stream course as soon as practicable after construction or prior to seasonal closures. Inspect the work site at suitable regular intervals during and after construction or maintenance activities to check on quality of the work and materials and identify need for mid-project corrections. Consider short- and long-term maintenance needs and unit capabilities when designing the project. o Develop a strategy for providing emergency maintenance when needed. Include implementation and effectiveness monitoring to evaluate success of the project in meeting design objectives and avoiding or minimizing unacceptable impacts to water quality. Consider long-term management of the site and nearby areas to promote project success. o Limit human, vehicle and livestock access to site as needed to allow for recovery of vegetation.
AqEco-4. Stream Channels and Shorelines As appropriate or when required: All Activities Use applicable practices of BMP AqEco-2 (Operations in Aquatic Ecosystems) when working in or near waterbodies. Stream channels Determine need to control channel grade to avoid or minimize erosion of channel bed and banks prior to selecting measures for bank stabilization or protection. o Incorporate grade control measures into project design as needed. Determine design flows based on the value or safety of area to be protected, repair cost and the sensitivity and value of the ecological system involved. o Obtain peak flow, low flow, channel forming flow and flow duration estimates. o Use these estimates to determine the best time to implement the project as well as to select design flows. Determine design velocities appropriate to the site. o Limit maximum velocity to that which is non-scouring on the least resistant streambed and bank material. o Consider needs to transport bedload through the reach when determining minimum velocities. o Maintain the depth-area-velocity relationship of the upstream channel through the project reach. o Consider the effects of design velocities on desired aquatic organism habitat and passage needs. Avoid changing channel alignment unless the change is to reconstruct the channel to a stable meander geometry consistent with stream type. Design streambank stabilization and protection measures suitable to channel alignment (straight reach versus curves). o Consider the effects of ice and freeze/thaw cycles on streambank erosion processes.
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Design channels with natural stream pattern and geometry, stable beds and banks and provide habitat complexity where reconstruction of stream channels is necessary. o Consider sediment load (bedload and suspended load) and bed material size to determine desired sediment transport rate when designing channels o Avoid relocating natural stream channels. o Return flow to natural channels where practicable. Include suitable measures to protect against erosion around the edges of stabilization structures o Design revetments and similar structures to include sufficient freeboard to avoid or minimize overtopping at curves or other points where high flow velocity can cause waves. o Use suitable measures to avoid or minimize water forces undermining the toe of the structure. o Tie structures into stable anchorage points, such as bridge abutments, rock outcrops or well-vegetated stable sections, to avoid or minimize erosion around the ends. o Add or remove rocks, wood, or other material in streams only if such action maintains or improves stream condition, provides for safety and stability at bridges and culverts, is needed to avoid or minimize excessive erosion of streambanks, or reduces flooding hazard. o Leave rocks and portions of wood that are embedded in beds or banks to avoid or minimize channel scour and maintain natural habitat complexity. o Choose vegetation appropriate to the site to provide streambank stabilization and protection adequate to achieve project objectives. o Use vegetation species and establishment methods suitable to the project site and objectives, consistent with local direction and requirements per FSM 2070 and FSM 2080 for vegetation ecology and prevention and control of invasive species.
Fac-10. Facility Reclamation As appropriate or when required: Regularly review the need for and use of stockpiles, materials, supplies, and facilities. Surplus, repurpose or recycle unneeded usable materials where practicable. o Dispose of unneeded materials through the appropriate solid waste handlers. Consult the Forest Pollution Prevention Coordinator for proper disposal of hazardous materials. Develop and implement reclamation plan to rehabilitate and restore, to the extent practicable, the natural ecological components, structures and processes consistent with Forest or Grassland Plan desired conditions, goals and objectives at sites where structures or facilities have been permanently removed. o Remove unneeded structures. o Re-establish original slope contours, surface and subsurface hydrologic pathways where practicable and as opportunities arise. o Improve infiltration capacity on compacted areas of the site. o Establish effective ground cover on disturbed sites to avoid or minimize accelerated erosion and soil loss. o Use suitable species and establishment techniques to revegetate the site in compliance with local direction and requirements per FSM 2070 and FSM 2080 for vegetation ecology and prevention and control of invasive species. o Stabilize disturbed streambed and banks (see BMP AqEco-4 (Stream Channels and Shorelines)).
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o Reconstruct or restore stream channels, wetlands, floodplains, and riparian areas to achieve desired conditions for aquatic ecosystem composition, structure, function and processes (see BMP AqEco-3 (Ponds and Wetlands) and BMP AqEco-4 (Stream Channels and Shorelines)). Decommission unneeded roads, trails and staging areas (see BMP Roads-6 (Road Storage and Decommissioning)). Consider long-term management of the site and nearby areas to promote project success. Limit human, vehicle and livestock access to site as needed to allow for recovery of vegetation.
Road-2. Road Location and Design As appropriate or when required: Location Locate roads to fit the terrain, follow natural contours and limit the need for excavation. o Avoid locations that require extended steep grades, sharp curves or switchbacks. Locate roads on stable geology with well-drained soils and rock formations that dip into the slope. Avoid hydric soils, inner gorges, overly steep slopes and unstable landforms to the extent practicable. Locate roads as far from waterbodies as is practicable to achieve access objectives, with a minimum number of crossings and connections between the road and the waterbody. Avoid sensitive areas such as riparian areas, wetlands, meadows, bogs and fens, to the extent practicable. Provide a SMZ of suitable width between the road and a waterbody to provide adequate filtering of sediment and other pollutants when a road must parallel a waterbody (See BMP Plan-3 (SMZ Planning)). Relocate existing routes or segments that are causing, or have the potential to cause, adverse effects to soil, water quality and/or riparian resources, to the extent practicable. Obliterate the existing road or segment after the relocated section is completed. Pre-Design Consider design criteria relative to soil, water quality and riparian resources from the Decision Document and associated NEPA document. Consider the road RMO and likely future maintenance schedule in the initial design. Conduct suitable site investigations, data collection and evaluations commensurate with the anticipated design and sensitivity of the area to soil, water quality and riparian resource impacts. Consider subsurface conditions and conduct suitable investigations and stability analyses for road and bridge locations where slope instability can occur due to road construction. Conduct a suitable soils and geotechnical evaluation to identify susceptibility to erosion and stable angles of repose. Design Design the road to fit the ground and terrain with the least practicable impacts to soil, water quality and riparian resources considering the purpose and life of the road, safety and cost. Use road standards that minimize impacts for grade and alignment (e.g. width, turning radius, maximum slope). Use “low impact design” (LID) treatments that reduce long-term maintenance needs wherever practicable. Design the road to maintain stable road prism, cut and fill slopes. o Design cut and fill slope ratios to reduce soil loss from mass failures.
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o Use structural or nonstructural measures as necessary to stabilize cut and fill slopes. Design the road surface drainage system to intercept, collect and remove water from the road surface and surrounding slopes in a manner that reduces concentrated flow in ditches, culverts and over fill slopes and road surfaces. o Use structural or nonstructural measures suitable to the road materials, road gradient and expected traffic levels. o Use an interval between drainage features that is suitable for the road gradient, surface material and climate. o Use suitable measures to avoid or minimize erosion of ditches. Design the road subsurface drainage system to intercept, collect and remove groundwater that may flow into the base course and subgrade, lower high water tables and drain water pockets. o Use suitable subsurface dispersion or collection measures to capture and disperse locally shallow groundwater flows intercepted by road cuts. o Use suitable measures to release groundwater into suitable channels without causing erosion or siltation. Design the road for minimal disruption of natural drainage patterns and to reduce the hydrologic connection of the road segment or network with nearby waterbodies. o Use structural or nonstructural measures to avoid or minimize gully formation and erosion of fill slopes at outfalls of road surface drainage structures. Provide sufficient buffer distance at the outfalls of road surface drainage structures for water to infiltrate prior to reaching the waterbody. Use applicable practices of BMP Road-7 (Stream Crossings) to limit the number and length of water crossing connected areas to the extent practicable. Design road surface treatment to support wheel loads, stabilize the roadbed, reduce dust and control erosion consistent with anticipated traffic and use. o Consider whether road closures or roadway surface drainage and erosion protection can adequately mitigate adverse effects to soil, water quality and riparian resources. Design roads within the SMZ (when there is no practicable alternative outside of the SMZ to achieve access objectives) to maintain desired conditions, goals and objectives for SMZ structure, function and processes (See BMP Plan-3 (SMZ Planning)). Design waterbody crossings to avoid or minimize adverse effects to soil, water quality and riparian resources to the extent practicable consistent with road use, legal requirements and cost considerations (See BMP Road-7 (Stream Crossings)). Design a post-construction site vegetation plan, including short- and long-term objectives, using suitable species and establishment techniques to revegetate the site in compliance with local direction and requirements per FSM 2070 and FSM 2080 for vegetation ecology and prevention and control of invasive species.
Road-5. Temporary Roads Practices: As appropriate or when required: Use applicable practices of BMP Road-2 (Road Location and Design) to locate temporary roads. Refer to state or local construction and stormwater BMP manuals, guidebooks and trade publications such as “Erosion Control” and “Stormwater” for effective techniques to: Apply soil protective cover on disturbed areas. Maintain the natural drainage pattern of the area wherever practicable. Control, collect, detain, treat and/or disperse surface runoff from the site.
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Divert surface runoff around bare areas with appropriate energy dissipation and sediment filters. Stabilize steep excavated slopes. Install sediment and stormwater controls prior to initiating surface disturbing activities to the extent practicable. Schedule construction activities to avoid direct soil and water disturbance during periods of the year when heavy precipitation and runoff are likely to occur. Routinely inspect temporary roads to verify that erosion and stormwater controls are implemented and functioning and are appropriately maintained. Maintain erosion and stormwater controls as necessary to ensure proper and effective functioning. Use suitable measures in compliance with local direction to prevent and control invasive species. Use temporary crossings suitable for the expected uses and timing of use (See BMP Road-7 (Stream Crossings)). Use applicable practices of BMP Road-6 (Road Storage and Decommissioning) to obliterate the temporary road and return the area to resource production once the access is no longer needed.
Road-6. Road Storage and Decommissioning As appropriate or when required: All Activities Implement suitable measures to close and/or physically block the road entrance so that unauthorized motorized vehicles cannot access the road. Remove the road from the MVUM and issue a closure order as necessary to inform the public. o Establish effective ground cover on disturbed sites to avoid or minimize accelerated erosion and soil loss. o Use suitable species and establishment techniques to stabilize and revegetate the site in compliance with local direction and requirements per FSM 2070 and FSM 2080 for vegetation ecology and prevention and control of invasive species. Road Conversion to Trail Reclaim unneeded road width, cut and fill slopes when converting a road for future use as a trail. Use suitable measures to stabilize reclaimed sections to avoid or minimize undesired access and to restore a desired ecologic structures or functions. Use suitable measures to ensure that surface drainage will intercept, collect and remove water from the trail surface and surrounding slopes in a manner that minimizes concentrated flow and erosion on the trail surfaces without frequent maintenance. Use applicable practices of BMP Road-7 (Stream Crossings) to provide waterbody crossings suitable to the expected trail uses.
Road-7. Stream Crossings As appropriate or when required: All Crossings Plan and locate surface water crossings to limit the number and extent to that which is necessary to provide the level of access needed to meet resource management objectives as described in the RMO.
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Use applicable practices of BMP AqEco-2 (Operations in Aquatic Ecosystems) when working in or near stream channels. Use crossing structures suitable for the site conditions and RMO. Design and locate crossings to minimize disturbance to the waterbody. Use suitable measures to locate, construct and decommission or stabilize bypass roads to avoid, minimize or mitigate adverse effects to soil, water quality and riparian resources. Use suitable surface drainage and roadway stabilization measures to disconnect the road from the waterbody to avoid or minimize water and sediment from being channeled into surface waters and to dissipate concentrated flows. Use suitable measures to avoid, minimize or mitigate damage to the waterbody and banks when transporting materials across the waterbody or SMZ during construction activities. Stream Crossings o Locate stream crossings where the channel is narrow, straight and uniform, has stable soils and relatively flat terrain to the extent practicable. o Select a site where erosion potential is low. o Orient the stream crossing perpendicular to the channel. o Keep approaches to stream crossings to as gentle a slope as practicable. o Consider natural channel adjustments and possible channel location changes over the design life of the structure. o Design the crossing to pass a normal range of flows for the site. o Design the crossing structure to have sufficient capacity to convey the design flow without appreciably altering stream flow characteristics. o Install stream crossings to sustain bankfull dimensions of width, depth and slope, and maintain streambed and bank resiliency and continuity through the structure. o Bridge, culvert or otherwise design road fill to prevent restriction of flood flows. o Use site conditions and local requirements to determine design flood flows. o Use suitable measures to protect fill from erosion and to avoid or minimize failure of the crossing at flood flows. o Use suitable measures to provide floodplain connectivity to the extent practicable. o Use suitable measures to avoid or minimize scour and erosion of the channel, crossing structure and foundation to maintain the stability of the channel and banks. o Design and construct the stream crossing to maintain the desired migration or other movement of fish and other aquatic life inhabiting the waterbody. o Install or maintain fish migration barriers only where needed to protect endangered, threatened, sensitive or unique native aquatic populations, and only where natural barriers do not exist. o Use stream simulation techniques where practicable to aid in crossing design. Low Water Crossings o Consider low water crossings on roads with low traffic volume and slow speeds. o Consider low water crossings to cross ephemeral streams, streams with relatively low baseflow and shallow water depth or streams with highly variable flows or in areas prone to landslides or debris flows. o Locate low water crossings where streambanks are low with gentle slopes and channels are not deeply incised.
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o Select and design low water crossing structures to maintain the function and bedload movement of the natural stream channel. o Locate unimproved fords in stable reaches with a firm rock or gravel base that has sufficient load bearing strength for the expected vehicle traffic. o Construct the low water crossing to conform to the site, channel shape and original streambed elevation, and to minimize flow restriction, site disturbance and channel blockage to the extent practicable. o Use suitable measures to stabilize/harden the streambed and approaches, including the entire “wetted perimeter” (e.g. area of high flow) and sufficient freeboard, where necessary to support the design vehicle traffic. o Use vented fords with high vent area ratio (VAR) to maintain stream function and aquatic organism passage. o Construct the roadway-driving surface with material suitable to resist expected shear stress or lateral forces of water flow at the site. o Consider using temporary crossings on roads that provide short-term or intermittent access to avoid, minimize or mitigate erosion, damage to streambed or channel and flooding. o Design and install temporary crossings suitable for the expected users, loads and timing of use. o Design and install temporary crossing structures to pass a design storm determined based on local site conditions and requirements. o Use suitable measures to protect fill from erosion and to avoid or minimize failure of the crossing. o Install and remove temporary crossing structures in a timely manner as needed to provide access during use periods and minimize risk of washout. o Use suitable measures to stabilize temporary crossings that must remain in place during high runoff seasons. o Monitor temporary crossings regularly while installed to evaluate condition. o Remove temporary crossings and restore the waterbody profile and substrate when the need for the crossing no longer exists.
Road-9. Parking and Staging Areas Develop site-specific BMP prescriptions for the following practices, as appropriate or when required,using State BMPs, Forest Service regional guidance, land management plan direction, BMP monitoring information, and professional judgment. Design and locate parking and staging areas of appropriate size and configuration to accommodate expected vehicles and avoid or minimize adverse effects to adjacent soil, water quality, and riparian resources. o Consider the number and type of vehicles to determine parking or staging area size. o Use applicable practices of BMP Fac-2 (Facility Construction and Stormwater Control) for stormwater management and erosion control when designing, constructing, reconstructing, or maintaining parking or staging areas. o Use suitable measures to harden and avoid or minimize damage to parking area surfaces that experience heavy use or are used during wet periods. o Use and maintain suitable measures to collect and contain oil and grease in larger parking lots with high use and where drainage discharges directly to streams. o Connect drainage system to existing stormwater conveyance systems where available and practicable.
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o Conduct maintenance activities commensurate with parking or staging area surfacing and drainage requirements as well as precipitation timing, intensity, and duration. o Limit the size and extent of temporary parking or staging areas. o Take advantage of existing openings, sites away from waterbodies, and areas that are apt to be more easily restored to the extent practicable. o Use temporary stormwater and erosion control measures as needed. o Use applicable practices of BMP Fac-10 (Facility Site Reclamation) to rehabilitate temporary parking or staging areas as soon as practicable following use.
Road-10. Equipment Refueling and Servicing As appropriate or when required: Plan for suitable equipment refueling and servicing sites during project design. Allow temporary refueling and servicing only at approved locations, located well away from water or riparian resources. Develop or use existing fuel and chemical management plans (e.g. SPCC, spill response plan, emergency response plan) when developing the management prescription for refueling and servicing sites. Locate, design, construct and maintain petroleum and chemical delivery and storage facilities consistent with applicable local, state and federal regulations. Use suitable measures around vehicle service, storage and refueling areas, chemical storage and use areas, and waste dumps to fully contain spills and avoid or minimize soil contamination and seepage to groundwater. Provide training for all agency personnel handling fuels and chemicals in their proper use, handling, storage and disposal. o Ensure that contractors and permit holders provide documentation of proper training in handling hazardous materials. Use suitable measures to avoid spilling fuels, lubricants, cleaners and other chemicals during handling and transporting. Prohibit excess chemicals or wastes from being stored or accumulated in the project area. Remove service residues, used oil and other hazardous or undesirable materials from NFS land and properly dispose them as needed during and following completion of the project. Clean up and dispose of spilled materials according to specified requirements in the appropriate guiding document. Report spills and initiate suitable clean-up action in accordance with applicable state and federal laws, rules and regulations. Remove contaminated soil and other material from NFS lands and dispose of this material in a manner according to controlling regulations. Prepare and implement a certified SPCC Plan for each facility, including mobile and portable facilities, as required by federal regulations. Use applicable practices of BMP Fac-10 (Facility Reclamation) to reclaim equipment refueling and services site when the need for them ends. Design and locate parking and staging areas of appropriate size and configuration to accommodate expected vehicles and avoid or minimize adverse effects to adjacent soil, water quality, and riparian resources
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Uses-6. Dam Removal As appropriate or when required: Planning Use applicable practices of BMP AqEco-1 (Aquatic Ecosystem Improvement and Restoration Planning) when planning dam decommissioning/removal projects. Evaluate system hydrology and hydraulics to assess how effectively dam removal would allow aquatic species passage, potential flood impacts at various flows and potential impacts to surrounding infrastructure. Develop a sediment management plan (e.g. natural erosion, dredging, stabilization in place, relocation on or off-site or a combination of methods) that best suits sediment quality, quantity and physical characteristics, as well as the sensitivity of downstream reaches and/or the river’s ability to transport sediment. o Quantitatively determine sediment volume and physical parameters including grain size distribution, density, shear strength, cohesion, stratification, natural armoring potential, organic content and moisture content. Evaluate potential for contaminants trapped behind the dam by considering current and past upstream land uses such as industrial activity and road density and/or adequately sampling and analyzing sediments to determine the contamination level, if any, and graduation and distribution. o Estimate sediment transport to address fate of released sediment and potential contaminants. Identify the various aquatic and aquatic-dependent species that live in the river or on the floodplain and their life histories to determine protection strategies, including timing of dam removal, sediment management, species relocation and/or monitoring during construction. Evaluate floodplain and instream infrastructure to determine whether bridges, culverts, utility pipes or other infrastructure might be affected, particularly by the drop of water level in the impoundment. Develop a channel and vegetation restoration plan (see BMP AqEco-4 (Stream Channels and Shorelines) and BMP Fac-10 (Facility Reclamation)). Evaluate the need for active and/or natural channel and bank reconstruction. Evaluate the need for active and/or natural re-vegetation of exposed and disturbed sites. Determine necessary federal, state and local permits needed for dam removal. Construction Use applicable practices of BMP AqEco-2 (Operations in Aquatic Ecosystems) when removing dams. Remove or otherwise mitigate the sediment stored behind the impoundment prior to dismantling the structure. Drain the impoundment prior to removing structures to avoid downstream flooding and channel erosion. Drain the impoundment slowly to minimize release of sediment downstream, allow bed of impoundment and stream to drain and stabilize, and avoid a sudden release of water that could unnecessarily damage downstream infrastructure or habitat. Consider drawing down the impoundment during a time when exposed sediments would have an opportunity to stabilize and revegetate before structural removal of the dam. Demolish the structure in an efficient manner that avoids or minimizes adverse environmental effects to the extent practicable. Remove entire vertical extent of the dam structure and as much of the lateral extent as practicable. Consider phasing a project to minimize short-term impacts on the environment, beginning with out of channel work early in the phasing to accelerate and facilitate the removal process.
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Stabilize or relocate affected floodplain and instream infrastructure as needed to avoid, minimize or mitigate adverse effects. Restoration Use applicable practices of BMP AqEco-4 (Stream Channels and Shorelines) to restore streams when dams are removed. Use applicable practices of BMP Fac-10 (Facility Reclamation) to reclaim dam and associated infrastructure sites when dams are decommissioned. Simulate natural portions of surrounding stream or other nearby habitat to restore habitat more effectively.
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