Draft November 2017 Initial Study – Mitigated Negative Declaration for the Sweetwater Dam and South Dike Improvements Project State Clearinghouse Number: TBD
Prepared for: Sweetwater Authority 505 Garrett Avenue Chula Vista, California 91910 Prepared by: Amec Foster Wheeler Environment & Infrastructure, Inc. 9210 Sky Park Court, Suite 200 San Diego, California 92123
DRAFT INITIAL STUDY/MITIGATED NEGATIVE DECLARATION FOR THE SWEETWATER DAM AND SOUTH DIKE IMPROVEMENTS PROJECT
Prepared for:
Sweetwater Authority 505 Garrett Avenue Chula Vista, California 91910
Prepared by:
Amec Foster Wheeler Environment & Infrastructure, Inc. 9210 Sky Park Court, Suite 200 San Diego, California
Reviewed by:
Sweetwater Authority Ron R. Mosher, Director of Engineering Michael Garrod, Engineering Manager Pete Famolaro, Biologist Israel Marquez, Environmental Specialist
November 2017
Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
TABLE OF CONTENTS Page ACRONYMS AND ABBREVIATIONS ...... iv 1.0 PROJECT DESCRIPTION ...... 1 1.1 Introduction ...... 1 1.2 Project Location ...... 2 1.2.1 Environmental Setting ...... 2 1.2.2 Surrounding Land Uses ...... 3 1.3 Project Background ...... 3 1.4 Project Objectives and Scope ...... 8 1.5 Project Elements ...... 8 1.5.1 Sweetwater Dam Improvements ...... 8 1.5.2 South Spillway Improvements ...... 13 1.5.3 South Dike Improvements ...... 14 1.5.4 Fishing Program Access Road Realignment ...... 17 1.5.5 Trail Realignment ...... 17 1.5.6 South Abutment Access Road Improvements ...... 17 1.6 Project Design Considerations ...... 18 1.7 Project Construction ...... 20 1.7.1 Construction Timing and Phasing ...... 20 1.7.2 Construction Equipment and Staging Areas ...... 21 1.7.3 Construction Haul Routes ...... 22 1.7.4 Construction Activities ...... 22 1.8 Required Agency Review and Permit Approvals ...... 23 2.0 EVALUATION OF ENVIRONMENTAL IMPACTS ...... 25 3.0 ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED ...... 26 4.0 DETERMINATION ...... 27 4.1 Aesthetics ...... 28 4.1.1 Existing Setting ...... 28 4.1.2 Discussion ...... 29 4.2 Agricultural and Forestry Resources ...... 31 4.2.1 Existing Setting ...... 32 4.2.2 Discussion ...... 32 4.3 Air Quality ...... 33 4.3.1 Existing Setting ...... 33 4.3.2 Discussion ...... 34 4.4 Biological Resources ...... 39 4.4.1 Existing Setting ...... 40 4.4.2 Discussion ...... 47 4.5 Cultural Resources ...... 61 4.5.1 Existing Setting ...... 61 4.5.2 Discussion ...... 64 4.6 Geology and Soils ...... 68 4.6.1 Existing Setting ...... 69 4.6.2 Discussion ...... 70
Page i Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
TABLE OF CONTENTS (CONTINUED) Page 4.7 Greenhouse Gas Emissions ...... 73 4.7.1 Existing Setting ...... 73 4.7.2 Discussion ...... 74 4.8 Hazards and Hazardous Materials ...... 75 4.8.1 Existing Setting ...... 76 4.8.2 Discussion ...... 76 4.9 Hydrology and Water Quality...... 79 4.9.1 Existing Setting ...... 80 4.9.2 Discussion ...... 82 4.10 Land Use and Planning ...... 84 4.10.1 Existing Setting ...... 84 4.10.2 Discussion ...... 84 4.11 Mineral Resources ...... 86 4.11.1 Existing Setting ...... 86 4.11.2 Discussion ...... 86 4.12 Noise ...... 87 4.12.1 Existing Setting ...... 87 4.12.2 Discussion ...... 88 4.13 Population and Housing ...... 91 4.13.1 Existing Setting ...... 91 4.13.2 Discussion ...... 91 4.14 Public Services ...... 92 4.14.1 Existing Setting ...... 92 4.14.2 Discussion ...... 93 4.15 Recreation ...... 94 4.15.1 Existing Setting ...... 94 4.15.2 Discussion ...... 94 4.16 Transportation/Traffic ...... 97 4.16.1 Existing Setting ...... 98 4.16.2 Discussion ...... 98 4.17 Tribal Cultural Resources ...... 101 4.17.1 Existing Setting ...... 101 4.17.2 Discussion ...... 102 4.18 Utilities and Service Systems ...... 103 4.18.1 Existing Setting ...... 104 4.18.2 Discussion ...... 104 4.19 Mandatory Findings of Significance ...... 106 4.19.1 Discussion ...... 106 5.0 REFERENCES ...... 108
Page ii Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
LIST OF FIGURES
Figure 1. Project Vicinity ...... 4 Figure 2. Project Site ...... 7 Figure 3. Dam Improvements (Cross Sectional View) ...... 10 Figure 4. Dam Improvements (Plan View) ...... 11 Figure 5. South Spillway Improvements (Plan View) ...... 12 Figure 6. South Dike Improvements (Cross Sectional View) ...... 15 Figure 7. South Dike Improvements (Plan View) ...... 16 Figure 8. Federally Designated Critical Habitat ...... 43 Figure 9. Vegetation Impacts at the Dam ...... 54 Figure 10. Vegetation Impacts at the South Dike ...... 55 Figure 11. Impacts to Jurisdictional Waters at the Dam ...... 57 Figure 12. Impacts to Jurisdictional Waters at the South Dike ...... 58
LIST OF TABLES
Table 1. Discretionary Permits Potentially Required for the Proposed Improvements ...... 24 Table 2. Air Quality Significance Thresholds ...... 34 Table 3. Estimated Daily Maximum Construction Emissions (pounds per day) ...... 36 Table 4. Vegetation Communities and Habitats in the Survey Area ...... 41 Table 5. Impacts to Land Cover and Vegetation Communities ...... 53 Table 6. Impacts to Jurisdictional Waters ...... 56 Table 7. Soils within the Project Area ...... 70 Table 8. Estimated Construction GHG Emissions (MT CO2e/yr) ...... 74 Table 9. San Diego County Noise Standards ...... 88 Table 10. Typical Construction Noise Levels ...... 89 Table 11. Typical Noise Levels from Construction Equipment ...... 89
APPENDICES
Attachment A Air Quality Modeling Attachment B Biological Resources Technical Report Attachment C Phase I Cultural Resources Survey
Page iii Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
ACRONYMS AND ABBREVIATIONS
°F degrees Fahrenheit AB Assembly Bill APE Area of Potential Effect Authority Sweetwater Authority BMP Best Management Practice Cal Fire California Department of Forestry and Fire Protection Cal EPA California Environmental Protection Agency CAPCOA California Air Pollution Control Officers Association CARB California Air Resources Board CCR Code of California Regulations CDC California Department of Conservation CDF California Department of Forestry CDFW California Department of Fish and Wildlife CEQA California Environmental Quality Act CESA California Endangered Species Act CFCs chlorofluorocarbons CFR Code of Federal Regulations cfs cubic feet per second CGP Construction General Permit CGS California Geological Survey
CH4 methane CMP Construction Management Plan CNEL Community Noise Equivalent Level CNPS California Native Plant Society CO carbon monoxide
CO2 carbon dioxide CPA Community Planning Area CRHR California Register of Historic Resources CRPR California Rare Plant Rank CUPA Certified Union Program Agency CWA Clean Water Act cy cubic yard dB decibel
Page iv Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
ACRONYMS AND ABBREVIATIONS (CONTINUED)
dBA A-weighted decibel DOC California Department of Conservation DSOD Division of Safety of Dams DTSC Department of Toxic Substances Control DWR Department of Water Resources EIR Environmental Impact Report ESA Endangered Species Act FEMA Federal Emergency Management Agency FPD Fire Protection District GEI GEI Consultants, Inc. GHG greenhouse gas HA Hydrologic Area HCFC hydrochlorofluorocarbon HCP Habitat Conservation Plan HMP Habitat Management Program HMR Hydrometeorological Report HSA Hydrologic Subarea HU Hydrologic Unit IS Initial Study LOS Level of Service LRA Local Responsibility Area LSAA Lake and Streambed Alteration Agreement MBTA Migratory Bird Treaty Act MM Mitigation Measure MND Mitigated Negative Declaration mph miles per hour MRZ Mineral Resource Zone MSCP Multiple Species Conservation Program MSL Mean Sea Level MTS Metropolitan Transit
N2O nitrous oxide NAHC Native American Heritage Commission NC&O National City and Otay Railroad
Page v Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
ACRONYMS AND ABBREVIATIONS (CONTINUED)
NCCP Natural Community Conservation Plan NCTD North County Transit District ND Negative Declaration NHPA National Historic Preservation Act NOI Notice of Intent NOP Notice of Preparation
NOx nitrogen oxides NPDES National Pollutant Discharge Elimination System NRCS Natural Resources Conservation Service NRHP National Register of Historic Places NWP Nationwide Permit NWS National Weather Service
O3 ozone
PM10 Respirable Particulate Matter
PM2.5 Fine Particulate Matter PMF Probable Maximum Flood PMP Probable Maximum Precipitation RAQS Regional Air Quality Strategy ROG Reactive Organic Gas RWQCB Regional Water Quality Control Board SANDAG San Diego Association of Governments SCIC South Coastal Information Center SDAB San Diego Air Basin SDAPCD San Diego Air Pollution Control District sf square foot SMARA California Surface Mining and Reclamation Act of 1975
SO2 sulfur dioxide SR State Route SWPPP Storm Water Pollution Prevention Plan SWRCB State Water Resources Control Board URDS Urban Runoff Diversion System USACE U.S. Army Corps of Engineers USDA U.S. Department of Agriculture
Page vi Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
ACRONYMS AND ABBREVIATIONS (CONTINUED)
USFWS U.S. Fish and Wildlife Service USGS U.S. Geological Survey
Page ii Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
1.0 PROJECT DESCRIPTION
1.1 Introduction
Sweetwater Authority (Authority), as a Lead Agency pursuant to the California Environmental Quality Act Probable Maximum Flood: The (CEQA), is proposing improvements to the flood that may be expected from the Sweetwater Dam and the South Dike to safely pass most severe combination of critical and contain storm water flows associated with a meteorological and hydrological Probable Maximum Flood (PMF) event. In order to conditions that is reasonably possible achieve that primary objective (see Section 1.4, in the drainage basin under study. Project Objectives and Scope), an existing parapet wall on the north side of the dam would be raised and a new parapet wall would be constructed on the south side. Additionally, the South Dike would be raised. Other minor repairs and modifications to the Sweetwater Dam, South Spillway, and associated facilities would also be conducted. The proposed Project would fully comply with the California Department of Water Resources (DWR) Division of Safety of Dams (DSOD) regulatory program (California Water Code Division 3, Dams and Reservoirs).
The Authority has proposed improvements to the Sweetwater Dam (left) and modification of the South Dike (right) to address potential extreme flooding events, including the PMF.
The Sweetwater Dam was constructed along the Sweetwater River between 1886 and 1888 to form the 960-acre Sweetwater Reservoir. The main dam is a concrete arch structure that is approximately 108 feet in height and 700 feet long. The associated South Dike is an earthen embankment that was constructed in 1910 to contain water on the south side of the Sweetwater Reservoir. The Sweetwater Dam and associated South Dike are located in San Diego County, California, and are owned and operated by the Authority.
The Sweetwater Reservoir, which has a total storage capacity of 28,079 acre-feet of water, is operated in conjunction with Loveland Reservoir located approximately 19 miles upstream on the Sweetwater River to provide water to the Authority’s 32 square mile service area that includes National City, Bonita, and the western portion of Chula Vista. The Robert A. Perdue Water Treatment Plant, which is located on the north side of the Sweetwater Reservoir, treats water from the Sweetwater Reservoir before it is distributed to the Authority’s customers.
Page 1 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
1.2 Project Location
The proposed Project activities would occur on the west and south sides of the Sweetwater Reservoir, located in the Sweetwater River Watershed in southern San Diego County. The reservoir is approximately 7 miles upstream from the San Diego Bay, and surrounded by the unincorporated communities of Spring Valley to the north and Bonita to the south and west. The San Diego National Wildlife Refuge is located on the east side of the reservoir. The closest highways to the Project areas are State Route (SR-) 125, located 300 feet south from the South Dike, and SR-54, located approximately 650 feet west of the Sweetwater Dam. Portions of the City of Chula Vista and National City are located further downstream from the proposed Project area.
1.2.1 Environmental Setting
The dam was constructed on the Sweetwater River at the boundary of urban and rural areas located near the foot of San Miguel Mountain. The Sweetwater Reservoir is located on approximately 1,823 acres of land owned and managed by the Authority and provides a variety of beneficial uses including drinking water, recreation (e.g., shoreline fishing), and habitat for waterfowl. Further, the landside area of the Sweetwater Reservoir property provides a number of recreational opportunities. The 5-mile long Sweetwater Reservoir Riding and Hiking Trail is a County of San Diego trail, operated through a Revocable License Agreement granted by the Authority, and runs along the south side of Sweetwater Reservoir. Rolling topography in the vicinity of the dam ranges from 240 to 315 feet above mean sea level (MSL). Average annual temperatures range from 40 to 80 degrees Fahrenheit (°F) with annual rainfall averaging just above 15 inches. Vegetation communities within the Project site include coastal sage scrub, riparian woodland/scrub, eucalyptus woodland, areas of disturbed or ruderal vegetation, and areas that are actively maintained for treatment plant operations and general property management. The natural areas surrounding the reservoir provide valuable habitat and are managed for a number of special status wildlife and plant species including coastal California gnatcatcher (Polioptila californica californica), least Bell’s vireo (Vireo bellii pusillus), San Diego fairy shrimp (Branchinecta sandiegonensis), and Otay tarplant (Deinandra conjugens), among others.
Page 2 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
1.2.2 Surrounding Land Uses
The reservoir property is bordered by the community of Spring Valley to the north and the community of Bonita to the west and south. Single family residential homes intermixed with some general commercial and industrial land uses are located to the north of Sweetwater Reservoir, in the community of Spring Valley. To the southwest of the reservoir the community of Bonita is characterized by more rural, low density developments. Open space and recreation areas occur Sweetwater Dam was originally constructed between immediately to the southwest of the dam, 1886 and 1888. At the time of its completion it was the country’s largest masonry arch dam. Today it plays a including Sweetwater Summit Regional key role in delivering water to nearly 200,000 people in Park and the Bonita Golf Course (see the region. Figure 1). Further southwest of the SR- 125 overpass, the community of Bonita includes primarily residential land uses. The San Diego National Wildlife Refuge, which spans 11,152 acres from Jamul to Spring Valley and eastern Chula Vista, is located approximately 500 feet from the southern edge of Sweetwater Reservoir (see Figure 1). The refuge is the U.S. Fish and Wildlife Service’s (USFWS’s) contribution to the Multiple Species Conservation Program (MSCP), a landscape-wide habitat conservation plan to preserve habitat and species while allowing appropriate development (USFWS 2016).
1.3 Project Background
Sweetwater Dam was originally constructed between 1886 and 1888, with significant modifications made in 1911 and 1916. The dam is a curved concrete gravity structure with a hydraulic height of 108 feet (i.e., the difference between the lowest point of the stream bed and the center spillway) and length of approximately 700 feet. At its authorized storage elevation of 239 feet, the reservoir has a storage capacity of approximately 28,079 acre-feet (GEI Consultants, Inc. [GEI] 2016).1 As of August 14, 2017, Sweetwater Reservoir was at approximately 46 percent of its authorized capacity, with 12,849 acre-feet of water in storage (San Diego County Water Authority 2017).
1 1 acre-foot of water is 325,850 gallons, or enough to cover a football field (which is slightly larger than 1 acre) approximately 1 foot deep. Page 3 SPRING STREET
San Clemente LA MESA 125 5 UNIVERSITY AVENUE 15 Vista Oceanside Carlsbad 78 San Marcos Escondido CAMPO ROAD Encinitas SAN DIEGO COUNTY E 94 KENWOOD DRIV Solana Beach 94 Del Mar 56 Poway S SPRING W
E E
VALLEY E
T T
W Santee A 8 T TROY STREET E San R El Cajon
S Diego
P La Mesa
R R
I I N
N National City
G G S LEMON S +
SKYLINESKYLINE DDRIVERIVE
Coronado PROJECT SITE B
GROVE O U MILES Chula Vista
MASSACHUSETTS AVENUE L E Imperial Beach UNITED STATES V N A 012 R MEXICO D
125
LEMON GROVE AVENUE CARDIFF STREET JAMACHA ROAD 54 Sweetwater River
D R A M EV EA OUL DO JAMACH A B W B R
O
O
K
D
R
I SAN V E DIEGO SAN DIEGO San Miguel Sweetwater NATIONAL Mountain D WILDLIFE OA Reservoir R PROJECT EY REFUGE LL VA SITE ISE PARAD
S
W
E E T Sweetwater W CONDUIT ROAD A Summit T
E Regional
R R
R
54 R Park O O
A A
D D Bonita Golf Club Sweetwater Regional Park SAN MIGUEL ROAD
Rohr Park CENTRALCENTRAL AVENUE BONITA
125 PROCT OR VALLEY ROAD
CO RR AL C A N Y LEGEND O O N T AY R L O Incorporated City AKES RO AD A D OAD ES R San Diego County LAK AY CHULA OT Park/Open Space EAST H STREETSTREET VISTA San Diego National Wildlife Refuge SCALE IN MILES Stream N Lake/Pond/Reservoir 01
Project Vicinity FIGURE Sweetwater Dam 1
Page 4 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
The Sweetwater Dam includes three principal spillways, referred to as the North, Center, and South Spillways, which are passive spillways that function when the reservoir is full. The dam also contains outlet structures for releases to the Robert A. Perdue Treatment Plant, and additional outlet structures for releasing water to the river below the dam in the event of an emergency. The face of the dam includes upstream parapet walls (i.e., barriers which are extensions of the dam wall at the edge of a structure) along the north and south ends of the dam, which form the crest of the dam at an elevation of 252 feet. In the event of flood conditions, these walls are intended to guide water over the Center Spillway (i.e., over the center of the curved face of the dam, which has a lower crest elevation of 241 feet), into the stilling basin downstream of the dam.
Sweetwater Reservoir (pictured above in June 2017) has a surface area of approximately 960 acres and a storage capacity of approximately 28,079 acre-feet. The Authority provides water to over 191,500 people in San Diego County.
The California Water Code Division 3, Dams and Reservoirs, provides for supervision over non- federally owned dams and entrusts this regulatory authority to the DWR, which delegates the program to DSOD. DSOD requires that all dams within its jurisdiction be capable of adequately passing a selected design flood.2 A method has been devised by DSOD to determine the hydrologic adequacy of any spillway in California on a rational and consistent basis (DSOD 1981). Due to the high hazard potential related to potential loss of life, economic loss, and environmental damage associated with potential failure or overtopping of the Sweetwater Dam, DSOD requires a design flood analysis using the PMF (Gutierrez 2016), which is defined as the flood that may be expected from the most severe combination of critical meteorological and hydrological conditions that is reasonably possible in the drainage basin under study. This PMF analysis is based on the Probable Maximum Precipitation (PMP), defined as the greatest amount of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location during a certain time of the year.
2 Design floods are hypothetical floods used for planning and floodplain management investigations. A design flood is defined by its probability of occurrence. It represents a flood which has a particular probability of occurring in any one year. Page 5 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
The last PMF analysis performed by DSOD for Sweetwater Dam was conducted in 1981, using the National Weather Service (NWS) Hydrometeorological Report (HMR) 36 (NWS 1969) and 49 (NWS 1977). An updated analysis was performed by GEI in 2013 (GEI 2013), using the revised PMP estimates for California, which captured more detailed data related to California terrain and climate influences (i.e., HMR 58 [NWS 1998] and HMR 59 [NWS 1999]). This analysis determined that the PMF could result in a maximum reservoir elevation of 257.3 feet, approximately 5.3 feet above the existing parapet walls and 3.3 feet above the existing South Dike (GEI 2016). Consequently, this analysis demonstrated that during a PMF event, the existing parapet walls would not be effective in guiding water from the reservoir over the Center Spillway. Rather, the water from the reservoir could overtop the parapet walls, resulting in the potential for significant erosion of the rock abutments of the Sweetwater Dam (i.e., the vegetated slide slopes on either side of the dam). Following hydrologic analyses conducted by GEI (2013), DSOD raised concerns regarding public safety should the Sweetwater Dam and/or South Dike be overtopped during a severe flood event. Consequently, the Authority proposed improvements to the Sweetwater Dam and South Dike in order to safely pass the PMF. In addition to the overtopping concerns, the South Spillway of Sweetwater Dam is also in need of repair due to deterioration of concrete and steel elements of the structure. Authority staff and GEI met with DSOD on December 5, 2013 to discuss the proposed improvements, as well as Flooding associated with a PMF could result in repairs to the South Spillway. In a December erosion of the dam’s rock abutments and under 20, 2013 letter, DSOD agreed with the catastrophic conditions, could result in abutment proposed modifications described above to failure and substantial downstream flooding into address spillway deficiencies at Sweetwater the valley below as occurred during the Great Dam. DSOD indicated that every effort should Flood of 1916. be made to complete all work within 5 years.
Page 6 LEGEND Existing Trail to be Abandoned Robert A. Perdue Realigned Trail Segment Water Treatment Plant 1 Fishing Program Access Road Realignment Sweetwater Reservoir Borrow Area
Sweetwater Dam Contractor Staging/Stockpile Area Work Area South Spillway Existing Regional Trail Existing Community Trail
Key 2 Sweetwater Reservoir Road 1 Haul Route 50-Foot Wide Vehicle Turnout 2 Conduit Road Haul Route Summit Meadow Road 3 Haul Route Aerial Source: Google 2017. South Abutment Access Road
2
Conduit Road Rock Drain
S T AT
E RROUT SWEETWATER O UT CAMPGROUND South Dike E 125
1 2 5
BONITA 2 GOLF CLUB 125 OUTE SWEETWATER E R TAT SCALE IN FEET SUMMIT 3 S REGIONAL PARK N 0 750 P age 7 Project Site FIGURE Sweetwater Dam 2 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
1.4 Project Objectives and Scope
The following objectives have been identified for the proposed Project:
• Comply with DSOD regulations contained in California Water Code Division 3, Dams and Reservoirs by modifying the Sweetwater Dam and South Dike to safely pass the PMF, and to prevent any public safety or public health hazards in the surrounding communities;
• Accomplish the objective in the Updated Sweetwater Authority Strategic Plan (2017) to ensure that the dam can safely pass the PMF;
• Protect highly erodible areas by confining PMF discharges over dam’s spillways to areas protected by existing concrete walls and slabs and ultimately into the existing stilling basin at the base of the dam;
• Increase serviceable life of the South Spillway by restoring the spillway to its original service condition and more effectively allowing the spillway to perform its intended role in releasing water and preventing overtopping of the Sweetwater Dam;
• Widen and improve the existing access road between Sweetwater Dam and the South Dike to provide access for construction vehicles and equipment and continued access between the Sweetwater Dam and the South Dike; and
• Realign segments of the Sweetwater Reservoir Riding and Hiking Trail and the Fishing Program access road to allow for continued recreational use following improvements to the South Dike.
1.5 Project Elements
In order to achieve the Project objectives (refer to Section 1.4, Project Objectives and Scope) and to comply with DSOD regulations, the Authority has proposed a number of improvements to the Sweetwater Dam and South Dike and associated improvements to Authority-maintained access roads and trails. Extensive geotechnical work has been completed at the Sweetwater Dam over the last century. The design of the proposed improvements relies on the latest geotechnical exploration program that was performed at the site by GEI in December 2014 and January 2015. The proposed exploration program was submitted to DSOD for approval, and subsequently finalized to incorporate DSOD comments. Geotechnical data obtained from the exploration program, including the evaluation of borings, test pits, and other laboratory testing, are contained in a Geotechnical Data Report prepared by GEI (2015a, 2015b). The results of this analysis were incorporated into the design of the proposed Project elements described in detail below.
1.5.1 Sweetwater Dam Improvements
In order to achieve the Project objectives (refer to Section 1.4, Project Objectives and Scope) and to comply with DSOD regulations, the Authority proposes to raise the existing parapet walls on the north and south ends of the Sweetwater Dam so that high energy discharges from the PMF (up to approximately 118,000 cubic feet per second [cfs]) are prevented from flowing over the top of the parapet walls onto the highly erodible rock abutments. The main design objective is to Page 8 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
confine PMF discharges to the Center Spillway, which is protected by existing concrete walls and slabs, and to direct water into the existing stilling basin at the base of the dam by raising and fortifying the existing parapet walls on the north and south end of the dam such that overtopping of the walls would not occur during a PMF.
South Parapet Wall
North Parapet Wall Center Spillway
South Spillway
The existing parapet walls on the north and south ends of the dam will be raised to an elevation of 258.7 feet and fortified in order to direct water flow over the Center Spillway during a PMF.
North Parapet Wall
The proposed improvements to the north end of the dam would include raising the 125-foot long north parapet wall by 6.7 feet to an elevation of 258.7 feet, which would provide 1 foot of freeboard between the parapet wall and the maximum reservoir level. The location of the proposed new wall was selected such that PMF discharges on the north side of the spillway would be forced to flow onto existing concrete surfaces on the downstream face of the dam. The northern limit of the wall was selected to be a point on the north abutment necessary to prevent the reservoir from flowing around the right side of the wall during a PMF.
South Parapet Wall
At the south end of the dam, the proposed Project would include stabilizing the left abutment wingwall to resist PMF loading. The wingwall stabilization method includes the construction of a massive concrete block, approximately 7.5 feet wide and 99 feet long (see Figures 3 and 4), to add weight and stability to the existing structure. The northern extent of the block, together with a small training wall, would force PMF overtopping flows onto the concrete floor of the South Spillway discharge channel. The southern end of the top of the block will be embedded in the abutment to prevent the reservoir from flowing around the left side of the wall during a PMF. The concrete block, which would be tied into the dam and further strengthened with rebar, would raise the existing parapet wall at this location by 1.7 feet to an elevation of 258.7 feet. Similar to the improvements on the north end of the dam, the top elevation of the concrete block would provide 1 foot of freeboard between the top of the block and maximum reservoir level during a PMF.
Page 9
10 age P
ELEVATION (FEET) ELEVATION (FEET) 240 250 260 270 240 250 260 270 (Cross Sectional View) Dam Improvements South ParapetWall North ParapetWall 01 Source: FIGURE SCALE INFEET GEI2016. 3 5 Wall Stem Wall Footing Wall Footing Buttress New Parapet Wall
Wall Stem
North Spillway
Outlet Works Tower
Stilling Sweetwater Basin Reservoir
Retaining Wall South Spillway Concrete and Construction New Parapet Wall Materials Delivery Location
Retaining Wall LEGEND New Parapet Walls Contractor Staging/Stockpile Area SCALE IN FEET Source: GEI 2016. N Aerial Source: Google 2017. 080
Dam Improvements FIGURE (Plan View) 4
Page 11 LEGEND South Spillway Improvements Limit of Work Sweetwater Dam Source: GEI 2016. Aerial Source: Google 2017. Sweetwater Reservoir Stilling Basin
Concrete and Construction Spillway Sill Materials Delivery Replacement Location Lakeside ChannelChann Landside Channel Baffle Bench New Parapet Wall el Repair Grillage Beam In-Place Repair Existing South Abutment Existing Rock Access Road Floor Slab Overlay Outcrop (unimproved)
Primary and Secondary Existing Parapet Wall Crack Repair
50-Foot Vehicle Turnout
SCALE IN FEET N 065 P age 12
South Spillway Improvements FIGURE (Plan View) 5 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
1.5.2 South Spillway Improvements
The South Spillway is an ungated side-channel spillway on the south end of the dam (behind the south parapet wall) that discharges water downstream through three orifices that pass through the body of the dam. The side- channel weir has a concrete crest with 2-foot high wooden flashboards,3 creating a flashboard crest at an elevation of 239 feet. The existing South Spillway structures have not been re-built or substantially altered since their construction in 1911 and 1916. Based on various surveys and reports prepared between 1969 and 2001, the South Spillway exhibits substantial concrete deterioration including primary and secondary cracking, general spalling (i.e., breakage or flaking), and grillage deterioration (i.e., deterioration of the foundation support beams). In particular, the observed deterioration of the grillage beams is reducing their structural capacity. The reduction in beam cross section resulting from the loss of The South Spillway discharges water concrete reduces the ultimate compressive strength of downstream through three orifices that the beams. In order to accomplish the objective of pass through the body of the dam. restoring the South Spillway to its original service However, the concrete structure is condition the following improvements would be deteriorating and is in need of repair. implemented (refer to Figure 5):
• Spillway Channel Floors – The lakeside and landside spillway channel floors would be repaired “in-kind” to address observed concrete deterioration.4 • Lakeside Baffle Bench – The existing steel baffles would be removed, and the bench surface would be repaired in-kind to address observed concrete deterioration. • Primary Cracks – Primary cracks would be repaired to limit seepage and potential migration of earthfill materials, and to allow limited future differential movement. • Secondary Cracks – Where determined appropriate in the field during construction, secondary cracks (i.e., random cracks with limited extent) would be filled to limit seepage and potential migration of foundation/earthfill materials. • Localized Spalls and Exposed Reinforcement – Where determined appropriate in the field during construction, localized spalls and exposed reinforcement would be repaired “in- kind” to address observed deterioration. • Grillage Beams – Grillage beams would be repaired in-kind to address observed concrete deterioration, and to restore their original cross-section and axial capacity.
3 Flashboards can be used as means of raising the reservoir storage level above a fixed spillway crest level when the spillway is not needed for releasing floods. Flashboards usually consist of individual wooden boards, or structural panels anchored to the crest 4 “In-kind” repairs use the same or similar materials in the same or a similar location to address existing deterioration Page 13 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Grillage beams subjected to hydraulic drag forces imposed by passage of routed PMF flows through the spillway would be stiffened by the addition of transverse steel beams. • Spillway Crest – The existing timber flashboards on the spillway crest would be removed and replaced with a permanent, reinforced concrete weir. Handrails would be placed on the new spillway crest. • Landside Channel Wall Drains – Wall drains would be installed in the south sidewall of the landside channel. The purpose of the drains is to improve drainage conditions and reduce potential hydrostatic pressures on the wall.
As part of the proposed Project, improvements would include the replacement of deteriorating concrete grillage beams, which provide structural support spreading heavy loads over a wide area. While some of the existing grillage beams are in good condition, others exhibit cracking and spalling and would require reinforcement.
1.5.3 South Dike Improvements
The South Dike, which was originally constructed in 1910 and was reconstructed to its current configuration in 1916, is a 37-foot high earthfill embankment located approximately 4,000 feet southeast of Sweetwater Dam. The dike is configured as three-segments with a total length of approximately 1,150 feet with a crest width of approximately 8 feet, including an 18-inch wide concrete parapet. However, the maximum crest height of 37 feet only occurs for a small portion of the dike near its center, while the remainder of the dike is more typically 28 feet.
The Authority is proposing to raise the South Dike to accommodate the PMF by placing additional earthfill (approximately 25,000 cubic yards [cy]) on the landside slope of the existing crest, and by extending the dike laterally beyond the existing west and east ends. As proposed, the maximum structure height of the dike would be approximately 47 feet, with a total crest length of approximately 1,475 feet, and a total crest width of 12 feet (see Figure 6). The new embankment material would be placed on top of the existing South Dike, extending the landside toe of the dike approximately 20 feet to the south, and expanding the overall footprint of the South Dike by approximately 2.2 acres (see Figure 7). Expansion of the South Dike would require removal of grassland and ruderal vegetation on the landside of existing dike and the placement of fill materials in the incised drainage channel at the downstream toe near the center of the dike. Page 14 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Additionally, the improvements to the South Dike would require the minor realignment of a portion of the Sweetwater Reservoir Fishing Program access road as well as the relocation of an existing trail, which currently crosses at the toe of the South Dike. The new road alignment would have the same dimensions (i.e., 25 feet wide) and would have a 15-foot wide fire break on each side of the road. The trail would be realigned further south of the soil stockpile area and the new caretaker maintenance building (see Section 1.5.4, Trail Realignment).
The side slopes and base of the foundation excavation made in the drainage ditch area would be covered with a minimum 12-inch thick layer of filter sand to act as a As part of the proposed Project, the drainage blanket. The intent of the drainage blanket South Dike would be raised by would be to capture foundation seepage should it occur approximately 5 feet to contain the in this incised area, and to safely route it downstream. PMF. Additional embankment material (The drainage blanket would be a precautionary would be taken from the borrow area measure, as significant seepage through the foundation and placed on the landside of the dike is not expected based on past performance and the in order to raise and further reinforce the impervious nature of the foundation materials.) structure.
Earthfill for the South Dike would be taken from an existing soil stockpile that was previously constructed on an east to southeasterly-sloping hillside located approximately 200 feet to the southwest of the dike. This area has been used for over 25 years as a disposal site for spoils from trenching projects performed by the Authority (Ninyo & Moore 2011). Borrow material from the soil stockpile would be processed at the site (e.g., dug out and sifted for grainsize compatibility) prior to its use as South Dike embankment material.
Figure 6. South Dike Improvements (Cross Sectional View)
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S S 0 FIGURE of Fence of Fence Existing Existing Regional Trail Regional Trail Remove Section SCALE IN FEET 01 Remove and Remove and Relocate Signage Relocate Signage as Needed as Needed emove Fence Trail SUMMIT MEADOW Trail
ROAD Remove Fence Remove Fence Existing Community Community SUMMIT SWEETWATER REGIONAL PARK South Dike Raise South Dike Raise Approximate Toe of Approximate Toe of (Refer to Figure 6) (Refer to Figure 6) Line of Cross Section Line of Cross Section South Dike South Dike (Plan View) Remove Remove Vegetation Vegetation Parapet Wall Parapet Wall Protect Existing Protect Existing South Dike Improvements Unpaved Access Road Access Road Remove Remove Google 2017. Fence as Needed Fence as Needed GEI 2016. Borrow Area Contractor Staging/ Stockpile Area Existing South Dike Existing Regional Trail Source: Aerial Source: Existing Existing Regional Trail Regional Trail Remove and Relocate Access Gate Remove and Relocate Access Gate LEGEND
SOUTH ABUTMENT ACCESS ROAD South Dike Raise Area Existing Trail to be Abandoned Realigned Trail Segment Fishing Program Access Road Realignment Existing Existing Baseline Baseline Signage Signage Remove Remove South Dike South Dike Dike SUMMITROAD MEADOW
Page 16 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
1.5.4 Fishing Program Access Road Realignment
A portion of the private access road associated with the Sweetwater Reservoir Fishing Program, which is open to the public on Saturdays, Sundays and Mondays, would be relocated as shown in Figure 7. Relocation of the gravel road is necessary in order to accommodate the expanded footprint of the South Dike under the proposed Project. The new alignment of the road would have the same dimensions (i.e., 25 feet wide) and would have a 15-foot wide fire break on each side of the road, as previously required by the Bonita-Sunnyside Fire Protection District (Authority 2001).
1.5.5 Trail Realignment
As described in Section 1.2, Project Location a network of trails runs throughout Authority property and through portions of the Project site in the vicinity of the South Dike. The popular trail network, which originates at Sweetwater Regional Park, consists of approximately 5 miles of trail used primarily for hiking, mountain biking, and horseback riding. Because of its proximity to Sweetwater Campground, this trail is heavily used during weekends.
The South Dike improvements would include the relocation of an existing 0.25-mile segment of the trail alignment, which currently runs adjacent to the southern edge of the South Dike. Under the proposed Project, the 12- to 16-foot wide gravel trail would be realigned further to the south of the South Dike (refer to Figure 7). The proposed trail alignment would follow The existing segment of the Sweetwater near to the eastern edge of Summit Meadow Road, Reservoir Riding and Hiking Trail that before connecting to an existing dirt trail that traverses currently runs adjacent to the southern the incised drainage located to the south of the South edge of the South Dike will be rerouted Dike. Additionally, a new segment of trail would be further south as part of the proposed created, parallel to SR-125 to connect the existing Project. segment across the incised drainage with the remainder of the trail system.
1.5.6 South Abutment Access Road Improvements
Lakeside access for construction at the south end of the dam would be provided through the South Dike site, and then via an existing unpaved access road that starts near the South Dike, and generally follows the reservoir rim to a point approximately 170 feet southeast of the South Spillway. The existing road, beginning at Authority Gate 252, is a 12-foot wide improved gravel roadway for approximately 1,250 feet where it meets an existing turn around point. However, the 3,225-foot segment beyond the turnaround point to the South Spillway is an unimproved dirt roadway that varies in width and in some locations, particularly as it approaches the South Spillway, is overgrown with just two tire tracks remaining.
Page 17 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Under the proposed Project, the access road would be improved along its entire length to support a range of heavy construction vehicles (refer to Figure 2). The road would be widened to a uniform width of 20 feet, with a 35-foot wide turnout point along the road, and a 50-foot wide turnout point/staging area near the dam. Further, the road surface would be improved by laying down and compacting approximately 4 inches of aggregate road base (e.g., gravel). Additionally, the existing access road would be extended from its current terminus to meet the edge of the South Spillway. The widening and extension of the existing access road would require limited excavation and fill, particularly in the vicinity of the South Spillway. Improvements in this area would also require the removal of an existing rock outcrop and could require temporary restraining (refer to Figure 5). Additionally, a small concrete pipe culvert (less than 16 inches in diameter) may be Improvements to the South Abutment installed along the access road in order to enhance Access Road improvements would include drainage (refer to Figure 2). Following completion of widening and regrading of the existing road construction activities, the South Abutment Access to a width of 10 feet, which would require Road would remain in place to allow for future minor vegetation removal along the sides access for operation, maintenance, and monitoring of the existing unimproved dirt roadway. of the South Spillway. Consequently, future maintenance activities, such as vegetation removal along the roadway, clearing and maintenance of culverts, and minor re-grading following large storm events would be also expected.
1.6 Project Design Considerations
The proposed Project has been designed with close coordination between Authority engineers and environmental compliance staff in order to avoid and minimize, to the maximum extent possible, unnecessary impacts to environmental resources. Further, the following Project design features, measures and practices shall be implemented:
Aesthetics • Rocky outcrops – particularly in the vicinity of the south abutment – shall be preserved to the maximum extent practicable, and revegetation shall follow project activities, as specified in Section 4.4, Biological Resources. • If project lighting is required during construction, standard measures (e.g., screening) shall be taken to minimize spillover to the maximum extent feasible. Air Quality • The construction contractor shall be required to conform to all existing San Diego Air Pollution Control District (SDAPCD) rules and regulations related to dust control and
Page 18 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
reduction of emissions of particulate matter. Dust abatement measures shall be implemented during all construction activities. Biological Resources • Construction activities and staging shall avoid sensitive habitats – including coastal sage scrub, wetland, and vernal pool – to the maximum extent feasible. • Removal of vegetation shall occur outside of the nesting season for birds. If unavoidable, a pre-construction nesting bird survey by a qualified biologist could determine if nesting birds are in the work area. Project activities shall not indirectly harm or preclude nesting bird activity (typically within 300 feet for passerine birds and 500 feet for raptors). If a nest is found, the type of construction activity would be evaluated and avoidance methods would be implemented as necessary. Any buffer width would be determined by a qualified biologist at the time of discovery, and constraint measures would be monitored to evaluate effectiveness.
• A qualified biologist shall conduct preconstruction surveys for active bat roosts within 30 days and within 200 feet of disturbance activities where suitable roost habitat is present (e.g., trees, structures, bridges, rock formations). If an active maternity roost is located and the proposed Project cannot avoid removal of the occupied tree, demolition shall commence before maternity colonies form or after young are flying. Disturbance-free buffer zones as determined by a qualified biologist shall be delineated and observed during the maternity roost season.
• Prior to initiation of project construction, during the Otay tarplant blooming period, pre- construction surveys for individuals shall be performed by a qualified biologist. Available seed would be salvaged for future restoration prior to construction. • Construction contractor education, including discussions regarding timing, restrictions, and/or pre-construction surveys, shall be implemented as necessary to reduce potential disturbance impacts. • In-kind mitigation measures such as on-site revegetation following construction would be performed for temporary impacts areas and permanent impacts areas would be mitigated through conservation and management of similar habitat types in off-site locations (see Section 4.4, Biological Resources). Geology and Soils • Project design and construction elements shall comply with DSOD and Authority standards. • Project plans shall be reviewed to ensure compatibility with final geotechnical recommendations. Hazards and Hazardous Materials • Storage of the necessary amount of hazardous materials on site shall be restricted, to the maximum extent practicable, to areas at least 50 feet from storm drains, the reservoir, and water courses.
Page 19 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
• Standard construction best management practices (BMPs) shall be implemented to prevent impacts to the public and resources through the transport, use, or disposal of construction fuels and lubricants. • Petroleum products, including diesel, gasoline, hydraulic fluids, would be used during construction in compliance with federal, state, and local laws and regulations. • In the event that hazardous materials are generated or encountered during construction, contractors certified by the responsible agency would conduct all recovery operations and dispose of hazardous waste in accordance with existing regulations and acquired permits. • During construction, all staging areas or construction areas where spark-producing equipment would be used shall be cleared of dried vegetation or other material that could ignite. Any construction equipment that includes a spark arrestor shall be equipped with a spark arrestor in good working order. During construction, all vehicles and crews shall have access to functional fire extinguishers at all times. Hydrology and Water Quality • The construction contractor shall be required to develop and implement a Stormwater Pollution Prevention Plan (SWPPP) for the Project. The SWPPP shall include a description of facilities, products and procedures to meet the erosion prevention and sediment control requirements of all applicable laws and regulations, and required Project permits. The SWPPP will include a storm water sampling and analysis strategy program pursuant to the existing regulatory guidelines (e.g., rain event action plan). Other detail BMPs will be included in the Plan to prevent impacts to water quality. • All active construction areas, unpaved access roads, parking areas, and staging areas shall be watered at least two times per day and/or stabilized with nontoxic soil stabilizers as needed to control fugitive dust. Exposed stockpiles (e.g., dirt, sand, etc.) shall be covered and/or watered or stabilized with nontoxic soil binders as needed to control emissions. Traffic • The construction contractor shall be required to prepare and comply with a Traffic Plan. This Traffic Plan shall be submitted for review by the Authority and for final approval by the County of San Diego before the commencement of construction-related activities. Utilities and Public Services • The Authority shall coordinate with all other utility providers that own easements, rights- of-way, or facilities within or adjacent to the area impacted by the proposed improvements.
1.7 Project Construction
1.7.1 Construction Timing and Phasing
Construction of the Project would take place over an approximate 12- to 16-month period, beginning in December 2017. The precise construction schedule would be dependent on the timing of the project entitlements and approval, but per direction from DSOD the construction of the improvements to safely pass the PMF are intended to be completed by approximately February 2019. The proposed dam improvements would be constructed in three phases over
Page 20 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 approximately 300 construction days. Throughout the duration of construction activities, between 25 and 75 construction workers would be present at the reservoir, depending on the phase of construction.
1.7.2 Construction Equipment and Staging Areas
The proposed improvements would require the use of excavators, bulldozers, rollers, loaders, single- or double-axle dump trucks, concrete ready-mix trucks, concrete pump trucks, flat-bed semi-tractor/trailers, and cranes. This equipment, along with other construction contractor vehicles would be staged in existing asphalt parking lots or gravel areas within the immediate vicinity of the dam and the South Dike as well as two temporary construction staging areas described below:
• North End of the Dam: Construction equipment could be staged on the lakeside of the north end of the dam adjacent to the existing boat ramp. This area, which covers approximately 24,825 square feet, would require extensive vegetation removal (including removal of coastal sage scrub), minor grading and leveling, and placement of gravel prior to supporting heavy equipment. This area would potentially be used as a crane pad, as well as for direct construction access for concrete demolition and sawing, and staging of formwork, reinforcing steel, and other materials for the north end of the dam. • South Dike: Construction equipment for the proposed improvements to the South Dike would be staged just south of the existing South
Dike and east of the South Dike Borrow Area. The area on the lakeside of the dam This area has a network of existing improved would provide direct access to the access roads. However, the staging area itself north end of the dam and would may require minor regrading and leveling. This potentially be used for the staging of a area, which covers a total of 15,250 square feet, crane. would be used to stage heavy construction vehicles such as excavators, graders, dump trucks, and flat-bed semi-tractor/trailers necessary to move earthfill from the Borrow Area to the South Dike.
Page 21 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
1.7.3 Construction Haul Routes
Improvements under the proposed Project would require the delivery and removal of materials at the construction staging areas along the western and southwestern ends of the Sweetwater Reservoir (refer to Figure 2). Under the proposed Project materials delivery and concrete trucks supporting the construction activities at Sweetwater Dam would access the Project site either via Sweetwater Reservoir Road (lakeside) or Conduit Road (landside), which passes adjacent to the east of the Bonita Golf Course, where a swing gate is located separating the County-maintained road from the access road maintained by the Authority. Neither of these access ways would require improvements to support the proposed Project construction. The landside area of dam at the terminus of the Authority- maintained Conduit Road could be used as a crane The Conduit Road access road provides pad and/or as a location for concrete truck staging gated access to the base of the dam and and concrete pumping. Materials delivery trucks and would support materials delivery and other heavy construction equipment supporting the concrete truck staging during South Dike and South Spillway would access the site construction. via Summit Meadow Road accessing the construction staging areas via Authority Gates 250 and 252. No improvements to the paved Summit Meadow Road would be required. However, the Authority would improve the access road from Gate 252 to the South Spillway as previously described in Section 1.5.5, South Abutment Access Road Improvements.
1.7.4 Construction Activities
Specific construction site access and construction-related activities are discussed below:
North Parapet Wall
Access to the lakeside of the north parapet wall would be provided by the Robert A. Perdue Water Treatment Plant entrance, with heavy equipment accessing the Project area via the existing boat ramp. Construction activities in this location would include demolition (i.e., removal with a wire saw or diamond blade saw) of the existing 125-foot long parapet wall. Following demolition of the existing wall a 5-foot wide, 1.5-foot tall concrete wall footing would be poured and tied into the dam with rebar, which would be drilled and grouted into the dam. Additionally, a 9-foot tall, 1.5- foot wide new parapet wall would be poured on top of the wall footing raising the total elevation of the north end of the dam to 258.7 feet (refer to Figure 3). The concrete wall footing and concrete parapet wall would each be further strengthened with rebar and U-bar, which would be imbedded within the concrete structures.
Page 22 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
South Parapet Wall
Access to the lakeside area of the south parapet wall would be provided by the South Abutment Access Road, which would be improved as a part of the proposed Project (refer to Section 1.5.5, Road Improvements). Depending on the water level in the reservoir, lakeside access could also be provided by a barge mounted crane. (This would include a mobile crane sitting on “flexifloats” modular floats, which are common practice for inland marine work.) Improvements in this area would include pouring concrete for a 7.5-foot wide concrete block that would extend 99 feet along the top of the dam to support the existing left abutment wingwall. Similar to the improvements to the north end of the dam, the installation of the concrete block on the south end would include drilling and grouting the block into the existing dam. The concrete block would be further strengthened with rebar and U-bar, which would be imbedded within the concrete structures. Additionally, a 1.5-foot thick retaining wall would be installed on either side of the block to direct water flow into the center spillway and prevent erosion of the south abutment.
South Spillway
Access for the South Spillway Improvements would be provided by the South Abutment Access Road. The south spillway improvements would require hydro demolition of existing deteriorated concrete surfaces. The water and waste from this operation would need to be contained, recycled, and properly disposed of at an approved and licensed facility. Following demolition activities, new concrete would be poured to replace and repair deteriorated elements of the spillway. Removal and restoration of the grillage beams would also require temporary support and shoring of the spillway walls.
South Dike
Access for the South Dike Improvements would be provided by the existing gravel and dirt access roads in the area. Improvements at the South Dike would include the movement of earthfill by heavy equipment from the borrow area on top of the existing South Dike in order to raise the existing crest of the dike. The existing rock drain would be removed and replaced with a toe drain, which would capture runoff from the drainage blanket. Prior to construction, a borrow area management plan would be developed and would provide guidance for exploration/verification, moisture conditioning, full face excavation/mixing, final grading, best management practices, etc. Following the placement of earthfill from the borrow area, salvage riprap from the existing south dike would be placed on top of the fill.
1.8 Required Agency Review and Permit Approvals
The Authority is the Lead Agency for the proposed Project under the CEQA. However, the following agency approvals and/or permits may be required to implement the proposed Project (see Table 1). If a barge is needed to complete the work, the Authority would work with all applicable federal and state agencies with jurisdiction over this type of work, including the U.S. Army Corps of Engineers (USACE).
Page 23 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Table 1. Discretionary Permits Potentially Required for the Proposed Improvements
Permits and Authorizations Agency Activities Subject to Regulations Required
Nationwide Permit (NWP) Section Placement of dredge or fill materials into waters of USACE 404 of the Clean Water Act the U.S.
Consultation under Section 7 of the Potential impacts to federally-designated USFWS Federal Endangered Species Act endangered species (ESA)
Water Quality Certification Section Certification of NWP and discharges of waste that RWQCB 401 of the Clean Water Act and could affect waters of the state Waste Discharge Requirements
Compliance with the National Pollutant Discharge Elimination SWRCB, System (NPDES) General Storm Water Discharges associated with RWQCB Construction Permit, Order No. Construction and Land Disturbance Activities 2009-0009-DWQ through the preparation of a SWPPP
Divert or obstruct the natural flow of any river, Lake and Streambed Alteration stream or lake; deposit debris, waste or other CDFW Agreement (LSAA) Section 1602 materials that could pass into any river, stream or Permit lake.
Incidental Take Permit, Fish and Game Code, Sections 2081(b) and Potential incidental take of state-listed endangered CDFW (c) Consistency Determination species 2080.1
Federal Agencies State Agencies USACE = U.S. Army Corps of Engineers SWRCB = State Water Resources Control Board USFWS = U.S. Fish and Wildlife Service RWQCB = Regional Water Quality Control Board CDFW = California Department of Fish and Wildlife
Page 24 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
2.0 EVALUATION OF ENVIRONMENTAL IMPACTS
1) A brief explanation is required for all answers except "No Impact" answers that are adequately supported by the information sources a lead agency cites in the parentheses following each question. A "No Impact" answer is adequately supported if the referenced information sources show that the impact simply does not apply to projects like the one involved (e.g., the Project falls outside a fault rupture zone). A "No Impact" answer should be explained where it is based on project-specific factors as well as general standards (e.g., the project will not expose sensitive receptors to pollutants, based on a project- specific screening analysis). 2) All answers must take account of the whole action involved, including off-site as well as on-site, cumulative as well as project-level, indirect as well as direct, and construction as well as operational impacts. 3) Once the lead agency has determined that a particular physical impact may occur, then the checklist answers must indicate whether the impact is potentially significant, less than significant with mitigation, or less than significant. "Potentially Significant Impact" is appropriate if there is substantial evidence that an effect may be significant. If there are one or more "Potentially Significant Impact" entries when the determination is made, an EIR is required. 4) "Negative Declaration: Less Than Significant With Mitigation Incorporated" applies where the incorporation of mitigation measures has reduced an effect from "Potentially Significant Impact" to a "Less Than Significant Impact." The lead agency must describe the mitigation measures, and briefly explain how they reduce the effect to a less than significant level (mitigation measures from "Earlier Analyses," as described in (5) below, may be cross-referenced). a. Earlier analyses may be used where, pursuant to the tiering, program EIR, or other CEQA process, an effect has been adequately analyzed in an earlier EIR or negative declaration. Section 15063(c)(3)(D). In this case, a brief discussion should identify the following: • Earlier Analysis Used. Identify and state where they are available for review. • Impacts Adequately Addressed. Identify which effects from the above checklist were within the scope of and adequately analyzed in an earlier document pursuant to applicable legal standards, and state whether such effects were addressed by mitigation measures based on the earlier analysis. 5) Mitigation Measures. For effects that are "Less than Significant with Mitigation Measures Incorporated," describe the mitigation measures which were incorporated or refined from the earlier document and the extent to which they address site-specific conditions for the project. 6) Lead agencies are encouraged to incorporate into the checklist references to information sources for potential impacts (e.g., general plans, zoning ordinances). Reference to a previously prepared or outside document should, where appropriate, include a reference to the page or pages where the statement is substantiated.
Page 25 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
7) Supporting Information Sources: A source list should be attached, and other sources used or individuals contacted should be cited in the discussion. 8) This is only a suggested form, and lead agencies are free to use different formats; however, lead agencies should normally address the questions from this checklist that are relevant to a project's environmental effects in whatever format is selected. 9) The explanation of each issue should identify: a. The significance criteria or threshold, if any, used to evaluate each question; and b. The mitigation measure (MM) identified, if any, to reduce the impact to less than significance. 3.0 ENVIRONMENTAL FACTORS POTENTIALLY AFFECTED
The environmental factors checked below would be potentially affected by this Project, involving at least one impact that is a "Potentially Significant Impact" as indicated by the checklist and discussed on the following pages.
Agriculture and Forestry Aesthetics Air Quality Resources
Biological Resources Cultural Resources Geology/Soils
Greenhouse Gas Hazards & Hazardous Hydrology/ Water
Emissions Materials Quality
Land Use/Planning Mineral Resources Noise
Population/Housing Public Services Recreation
Tribal Cultural Utilities/Service Transportation/Traffic Resources Systems
Mandatory Findings of
Significance
Page 26 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.0 DETERMINATION
On the basis of this initial evaluation:
I find that the proposed project COULD NOT have a significant effect on the environment, and a NEGATIVE DECLARATION will be prepared.
I find that although the proposed project could have a significant effect on the environment, there will not be a significant effect in this case because revisions in the project have been made by or agreed to by the project proponent. A MITIGATED NEGATIVE DECLARATION will be prepared.
I find that the proposed project MAY have a significant effect on the environment, and an ENVIRONMENTAL IMPACT REPORT is required.
I find that the proposed project MAY have a "potentially significant impact" or "potentially significant unless mitigated" impact on the environment, but at least one effect 1) has been adequately analyzed in an earlier document pursuant to applicable legal standards, and 2) has been addressed by mitigation measures based on the earlier analysis as described on attached sheets. An ENVIRONMENTAL IMPACT REPORT is required, but it must analyze only the effects that remain to be addressed.
I find that although the proposed project could have a significant effect on the environment, because all potentially significant effects (a) have been analyzed adequately in an earlier EIR or NEGATIVE DECLARATION pursuant to applicable standards, and (b) have been
avoided or mitigated pursuant to that earlier EIR or NEGATIVE DECLARATION, including revisions or mitigation measures that are imposed upon the proposed project, nothing further is required.
______11/16/2017 Ron R. Mosher Date Director of Engineering Sweetwater Authority
Page 27 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.1 Aesthetics
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Have a substantial adverse
effect on a scenic vista? b) Substantially damage scenic resources, including, but not limited to, trees, rock
outcroppings, and historic buildings within a state scenic highway? c) Substantially degrade the existing visual character or
quality of the site and its surroundings? d) Create a new source of substantial light or glare that
would adversely affect day or nighttime views in the area?
4.1.1 Existing Setting
The Sweetwater watershed area is characterized by scenic landform features, including rolling hillsides and expansive views of the San Miguel Mountain ridgeline, which are visually attractive and also provide opportunities for recreation (e.g. hiking, mountain biking, etc.). The San Miguel Mountain ridgeline includes Mother Miguel Mountain, which is designated by the County General Plan as a resource conservation area within the Sweetwater Community Planning Area (CPA) (County of San Diego 2014). Large areas of open space and expansive unobstructed scenic vistas, including Mother Miguel Mountain, are important County visual resources (County of San Diego 2011b).
The Project area within the immediate vicinity of the Sweetwater Reservoir supports open space, recreational trails, and the reservoir, which spans approximately 960 acres. The areas immediately adjacent to the reservoir are distinguished by rocky terrain and vegetated open space. The Project area is also located adjacent to the northeast of the Sweetwater Regional Park and the associated 4.5-mile long trail network. The visual character of the Project area contains rural features including large open spaces surrounding the reservoir, recreational areas including the Sweetwater Regional Park and associated hiking and riding trails, and the Bonita Golf Course to the southwest. There are no state scenic highways in the Project area. However, Bonita Road, San Miguel Road, Guajolote Road, and Sweetwater River Road in the Project vicinity are designated by the County as first priority scenic routes (County of San Diego 2011b).
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4.1.2 Discussion a. Less than Significant. Implementation of the proposed Project would include short-term construction activities that would occur over approximately 300 construction days (refer to Section 1.7, Project Construction). The proposed Project staging areas at the north and south ends of the dam and at the South Dike would be potentially visible from public vantage points, particularly elevated areas surrounding the reservoir, as well as public trails (refer to Figure 2). The construction crew and heavy equipment The Sweetwater Dam is visible from SR-125, however at this scale improvements to the dam, would be partially visible from the including an increase in the elevation of the north Sweetwater Summit Regional Park and in parapet wall by 6.7 feet and the south parapet wall by the distance from SR-125 during short- 1.7 feet would be neglible. term construction activities. However, construction activities and associated staging of equipment would be temporary and would therefore not have a substantial long-term effect on scenic vistas in the vicinity of the Project. Once completed, permanent improvements to dam infrastructure and access roads would be potentially visible from elevated public vantage points along SR-125 as well as public hiking trails. However, proposed in-kind infrastructure improvements would not affect the overall visual appearance of existing facilities and the face of the dam and would also be constructed in a way that is consistent with the existing infrastructure. For example, the proposed parapets would be constructed with concrete, similar in visual character to the existing parapet walls. Additionally, these walls would raise the elevation of the dam by 6.7 feet (i.e., less than a 7-percent increase in the overall elevation of the dam), which would have negligible impacts on the semi-obstructed views from SR-125 and represent only a minor incremental change from area trails. Views of the South Dike from SR-125 are blocked by the existing grade adjacent to the road. The improvements to the South Dike would be visible from Sweetwater Summit Regional Park and along the trail system adjacent to the Sweetwater Reservoir; however, the proposed Project would raise the dike by Improvement to the access road at the south end of the dam would require the approximately 5 feet, and materials placed on the dike removal of some low lying vegetation would be consistent with the existing character of the as well as a number of eucalyptus dike. Overall, the proposed Project would have a less trees. than significant impact on scenic vistas.
Page 29 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 b, c. Less than Significant. There are no designated state scenic highways, historic buildings (see Section 4.5, Cultural Resources), or landmark trees in the Project area that would be adversely affected by the proposed Project. Additionally, as described above, impacts to vistas along County roads would be less than significant. The Project would result in minor grading and removal of the vegetated hillside adjacent to the South Abutment Access Road in order to widen the road to a uniform 20-foot width, with a 35-foot wide turnout point along the road. Additionally, the proposed Project would result in the removal of limited amounts of rocky terrain and a number of eucalyptus trees (Eucalyptus spp.) to support a 50-foot wide turnout point/staging area near the south end of the dam. However, this area is located immediately adjacent to the existing reservoir and existing improvements associated with the reservoir. The south end of the dam and the abutment road in this area is not visually prominent and is largely obstructed from publicly accessible views. As such, the rocky terrain in this area is not considered a scenic rock outcropping and removal to support the improvements to the South Abutment Access Road would not substantially effect recognized scenic resources in this area. The Project involves dam improvements and associated infrastructure improvements that would increase the height of the north parapet wall by 6.7 feet and the south parapet wall by 1.7 feet. Additionally, the proposed Project would raise the South Dike by 5 feet. However, proposed in-kind improvements and trail relocation associated with the South Dike improvements would not substantially change the visual character of the Project area or surrounding areas. The proposed Project would have a less than significant impact on scenic resources, visual character, and quality of the Project area and its surroundings. d. Less than Significant. Construction activities associated with the proposed Project would generally occur during the daytime hours. During the winter months, when the sun sets as early as 4:45 PM lighting may be required during the early evening hours. However, this lighting would be minimal and focused on the individual construction areas within the Project sites. In the event that lighting is required in more exposed areas, it would be screened from view as necessary (refer to Section 1.6, Project Design Considerations). Additionally, the construction-related lighting would be temporary and turned off or removed on a daily basis at the end of construction activities. Project construction activities would not include installation of materials that could be a potential new source of permanent light or glare. Following the completion of construction, there would be no long-term impacts related to lighting or glare.
Page 30 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.2 Agricultural and Forestry Resources
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated In determining whether impacts to forest resources, including timberland, are significant environmental effects, lead agencies may refer to information compiled by the California Department of Forestry and Fire Protection regarding the state’s inventory of forest land, including the Forest and Range Assessment Project and the Forest Legacy Assessment project; and forest carbon measurement methodology provided in Forest Protocols adopted by the California Air Resources Board (CARB). Would the Project: a) Convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency, to non-agricultural use? b) Conflict with existing zoning for agricultural use, or a Williamson Act contract? c) Conflict with existing zoning for, or cause rezoning of, forest land (as defined in Public Resources Code section 12220(g)), timberland (as defined by Public
Resources Code section 4526), or timberland zoned Timberland Production (as defined by Government Code section 51104(g))? d) Result in the loss of forest land or conversion of forest land to non-forest use? e) Involve other changes in the existing environment which, due to their location or nature, could result in conversion of Farmland to non-agricultural use or conversion of forest land to non- forest use?
Page 31 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.2.1 Existing Setting
The Project area is designated as Other Land (near the Dam), and Nonagricultural/Natural Vegetation (near the South Dike) by the California Department of Conservation (CDC) in San Diego County (CDC 2014). None of the land within the Project area is considered Prime Farmland, Unique Farmland, or Farmland of Statewide Importance.
4.2.2 Discussion a. No Impact. As described above, the CDC (2014) lists the entire Project site as within Other Land or Nonagricultural/Natural Vegetation Land. The proposed Project site does not contain any lands designated as Prime Farmland, Unique Farmland, or Farmland of Statewide Importance (CDC 2014) and therefore would not convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance to non-agricultural use. Further, the Project would involve the improvement of existing structures, and limited disturbance to on-site non-prime soils. Therefore, no impacts to farmland or agricultural soils would occur as a result of the implementation of the proposed Project. b – d. No Impact. The Project site is not presently zoned for agricultural land or forest land uses and is not under Williamson Act contract. The Project site is not designated as forest land and no loss of agricultural or forest land would result from Project implementation. Additionally, the proposed Project site does not contain a forest land zoning or land use designation and is not zoned for Timberland Production. Therefore, no impacts would occur as a result of the implementation of the proposed Project. e. No Impact. The proposed Project would not result in the conversion of active farmland to a non-agricultural use, nor a forest into a non-forested use. The property is not considered viable agricultural land due to repeated development, the existing informal recreation use on site, and the surrounding development. Using standard criteria for assessing agricultural viability (e.g. existing and surround land uses, soil disturbance, etc.), the proposed Project would not affect agricultural resources.
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4.3 Air Quality
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Where available, the significance criteria established by the applicable air quality management or air pollution control district may be relied upon to make the following determinations. Would the Project: a) Conflict with or obstruct implementation of the applicable air quality plan? b) Violate any air quality standard or contribute substantially to an
existing or projected air quality violation? c) Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is in non- attainment under an applicable
federal or state ambient air quality standard (including releasing emissions that exceed quantitative thresholds for ozone precursors)? d) Expose sensitive receptors to substantial pollutant concentrations? e) Create objectionable odors affecting a substantial number of people?
4.3.1 Existing Setting
The Project site is located within the San Diego Air Basin (SDAB). SDAB is currently designated nonattainment for ozone (O3), both 1-hour and 8-hour, and particulate matter, PM10 and PM2.5 under the California Ambient Air Quality Standards (CAAQS). It is designated attainment for CO, NO2, sulfur dioxide (SO2), lead, and sulfates. SDAPCD and San Diego Association of Governments (SANDAG) are responsible for developing and implementing the clean air plan for attainment and maintenance of the ambient air quality standards in the SDAB. The Regional Air Quality Strategy (RAQS) outlines SDAPCD’s plans and control measures designed to attain the State air quality standards for O3. The RAQS was initially adopted in 1991, and is updated on a triennial basis (most recently in 2016). The RAQS relies on information from the California Air Resources Board (CARB) and SANDAG, including mobile and area source emissions, as well as information regarding projected growth in San Diego County and the cities in the region, to project Page 33 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 future emissions and then determine the strategies necessary for the reduction of emissions through regulatory controls. CARB mobile source projections and SANDAG growth projections are based on population, vehicle trends, and land use plans adopted by the County of San Diego and the cities in the region as part of the development of their general plans.
As part of its air quality permitting process, the SDAPCD has established thresholds in Rule 20.2 requiring the preparation of Air Quality Impact Assessments (AQIAs) for permitted sources. The SDAPCD sets forth quantitative screening level thresholds below which a project would not have a significant impact on ambient air quality. For PM2.5, the U.S. Environmental Protection Agency’s (USEPA’s) “Proposed Rule to implement the Fine Particle National Ambient Air Quality Standards” (USEPA 2005) recommends a significance threshold of 10 tons per year, which equates to 55 pounds per day. Project-related air quality impacts estimated in this environmental analysis would be considered significant if any of the applicable significance thresholds presented in Table 2 are exceeded. For CEQA purposes, these screening criteria can be used as numeric methods to demonstrate that a proposed project’s total emissions would not result in a significant impact to air quality.
Table 2. Air Quality Significance Thresholds Pounds per Pounds per Pollutant Tons per Year Hour Day Carbon Monoxide (CO) 100 550 100 Nitrogen Oxides (NOx) 25 250 40 Respirable Particulate Matter (PM10) - 100 15 Fine Particulate Matter (PM2.5) - 55 10 Sulfur Oxides (SOx) 25 250 40 Lead (Pb) - 3.2 0.6 Reactive Organic Gases (ROGs) - 137 15 Sources: SDAPCD Rule 1501, 20.2 (d)(2); USEPA 2005.
4.3.2 Discussion a. Less than Significant. The RAQS relies on SANDAG growth projections, and as such, projects that propose development consistent with the growth anticipated by local plans would be consistent with the RAQS. However, if a project proposes development that is greater than that anticipated in the local plan and SANDAG’s growth projections, the project might conflict with the RAQS and may contribute to a potentially significant cumulative impact on air quality. The Project site is within areas designated as Public Agency Lands and is zoned S80 – Special Purpose (County of San Diego 2014; County of San Diego Planning and Development Services 2012). The proposed Project would not change the existing use of the Project site. Therefore, the proposed Project would be consistent with the San Diego County General Plan Land Use designations. Additionally, the implementation of the proposed Project would be limited to in-kind improvements. The proposed Project would neither directly introduce any new sources of operational emissions nor include any growth-inducing development. Because the proposed Project would not contribute to local population growth, or long-term employment growth and
Page 34 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 associated vehicle miles traveled, the proposed Project is considered to be accounted for in the RAQS, and the proposed Project would not conflict with or obstruct the implementation of local air quality plans. Overall, impacts associated with the implementation of the proposed Project would be less than significant. b. Less than Significant. The SDAPCD has recommended screening thresholds to provide guidance to local governments regarding the various types/amounts of land uses that may exceed state or federal air quality standards and would therefore result in potentially significant air quality impacts. Typically, two different screening significance thresholds are provided and include 1) construction thresholds; and 2) operation thresholds. As no long-term operational changes are anticipated, for purposes of the proposed Project, only the construction significance thresholds are relevant. Operational activities associated with the proposed Project would be similar to existing maintenance and management activities at the reservoir (e.g., culvert clearing, road maintenance, etc.), which are minimal and would not exceed the screening criteria for potential significant impacts. No other operational emissions would result from the construction of the proposed in-kind improvements.
Construction Emissions
Construction of the proposed Project would result in a temporary addition of pollutants to the local airshed caused by soil disturbance, dust emissions, and combustion pollutants from on-site construction equipment and off-site trucks hauling construction materials to and from the Project site. Fugitive dust emissions would primarily result from site preparation, grading of roads, soil excavation and fill activities. Oxides of nitrogen (NOx) and carbon monoxide (CO) emissions would primarily result from the use of construction equipment and motor vehicles.
Emissions from the construction phase of the proposed Project were estimated using the CalEEMod, Version 2016.3.2 model. For purposes of modeling, it was assumed that construction of the Project would commence in December 2017, and would occur in three phases over approximately 12 to 16 months:
• Phase 1 – South Abutment Road Access Grading and Construction (8 days) • Phase 2 – Dam, Spillway, and South Dike Demolition and Construction (300 days) • Phase 3 – Trail Realignment Grading (2 days)
While some equipment would be used for only several weeks during certain phases of construction, it was conservatively assumed that all equipment would operate for the entire duration of each construction phase associated with the proposed Project. Fugitive dust emissions during site preparation and road construction were estimated based on a “worst-case” assumption that the maximum disturbed area per day due to grading activities would be 1.09 acres per day in Phase 1, and 0.37 acres per day in Phase 3. While Phase 2 would include demolition and construction activities which would contribute to combustion emissions, extensive grading would not occur during this part of the proposed Project, and fugitive dust emissions would be negligible. A more detailed description of the construction schedule, including equipment utilized and construction equipment hours of duration, is included in the Air Quality Modeling provided in Attachment A.
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The equipment needed for construction activities associated with the proposed Project was developed based on a review of the proposed Project and reasonably conservative estimates of similar construction activities. To account for dust control measures in the calculations, it was assumed that the active sites would be watered at least two times per day to comply with SDAPCD Rule 55 (Fugitive Dust) and County Code Section 87.428 (Dust Control Measures). SDAPCD Rule 55 regulates fugitive dust emissions from any construction or demolition activity subject to the rule and capable of generating fugitive dust emissions, including active operations, open storage piles, and inactive disturbed areas, as well as track-out and carry-out onto paved roads beyond a project site. County Code Section 87.428 requires all clearing and grading to be carried out with dust control measures adequate to prevent creation of a nuisance to persons or public or private property. Soil watering has been shown to result in a decrease in particulate matter by approximately 55-percent reduction (USEPA 2006). Based on SDAPCD rules, clearing, grading, or improvement plans shall require that measures such as the following be undertaken to achieve this result: watering, application of surfactants, shrouding, control of vehicle speeds, paving of access areas, or other operational or technological measures to reduce dispersion of dust. These Project design measures, which are discussed further in Section 1.6, Project Design Considerations, would be incorporated into all earth-disturbing activities to minimize the amount of particulate matter emissions from construction.
Table 3 shows the estimated maximum daily construction emissions associated with the construction phase of the proposed Project. Complete details of the emissions calculations are provided in Attachment A.
Table 3. Estimated Daily Maximum Construction Emissions (pounds per day) Project Fugitive Dust* ROG NOx CO SO2 Construction Year PM10 PM2.5 2017 6.3548 44.4790 40.0442 0.0817 9.3941 4.3876 2018 5.7599 39.8539 37.4011 0.0805 9.1386 3.6648 2019 3.3048 28.5763 23.9878 0.0471 4.5171 2.8714 Peak Daily Total 6.3548 44.4790 40.0442 0.0817 9.3941 4.3876 Air District Threshold 137 250 550 250 100 15 Significant? No No No No No No Note: * The emissions of particulate matter accounts for the implementation of the dust control measures required under SDAPCD Rule 55 and County Code Section 87.428. No additional mitigation measures were applied as estimated daily maximum construction emission are below SDAPCD thresholds. Source: CalEEMod, Version 2016.3.2. See Attachment A for complete results.
As shown in Table 3, daily maximum construction emissions would not approach or exceed SDAPCD thresholds for Reactive Organic Gases (ROGs), NOx, CO, sulfur dioxide (SO2) or particulate matter less than 10 microns (PM10) and 2.5 microns (PM2.5). Therefore, air quality emissions associated with the construction of the Project would result in less than significant impacts.
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Operational Emissions
As discussed above, implementation of the proposed Project would neither introduce new operational sources of emissions nor substantially change existing operations at the Sweetwater Reservoir. Following completion of construction, minimal ongoing maintenance would be required to ensure that the improvements (e.g., South Abutment Access Road) remain in good condition, particularly following heavy storm events. However, these maintenance activities would be provided by existing operations staff at Sweetwater Reservoir, and would involve hand held tools and/or short-term temporary use of heavy construction equipment. Once constructed, the proposed Sweetwater Dam and South Dike improvements would otherwise function as constructed under existing conditions. Therefore, operational emissions associated with the proposed Project would be negligible. c. Less than significant. The SDAB has been designated as a federal nonattainment area for
O3 and a state nonattainment area for O3, PM10, and PM2.5. The nonattainment status is the result of cumulative emissions from all sources of these air pollutants and their precursors within the
SDAB. As discussed above and shown in Table 3, the emissions of ROGs, NOx, CO, SO2, PM10, and PM2.5 would be below significance thresholds during construction. The proposed Project would not require a land use change and would be compatible with existing uses at, and around, the site. Thus, the proposed Project would be consistent at a regional level with the underlying growth forecasts in the RAQS. The Project’s contribution to cumulative emissions would be minimal due to the short-term nature of the Project, as well as implementation of construction BMPs that would keep emissions below significance thresholds for these pollutants. No operational emissions would occur as a result of the proposed Project. Therefore, the proposed Project would not generate new operational air quality emissions that could result in a cumulatively considerable net increase of any criteria pollutant; thus, this impact is anticipated to be less than significant. d. Less than Significant. Construction activities for the proposed Project would be short-term and temporary and would be anticipated to generate insignificant criteria air pollutant emissions over the 12- to 16-month construction period. During construction, the proposed improvements to the South Dike could expose sensitive receptors using the hiking trail system immediately adjacent to the south of the South Dike. However, as specified in MM REC-1, trail users would be redirected around the construction area during construction, limiting the potential for direct exposure to fugitive dust and combustion-related emissions. Additionally, the South Dike is located over 500 feet away from Sweetwater Summit Regional Park and over 1,000 feet from the nearest residents. Similarly, the proposed construction areas at the dam and along the South Abutment Access Road are also located over 1,000 feet from the nearest residents. Construction activities in this area would not have impacts on these sensitive receptors. Further, the proposed Project would not generate new operational pollutant concentrations that could impact sensitive receptors such as children, older adults, or persons with preexisting respiratory or cardiovascular illness. Therefore, impacts are anticipated to be less than significant. e. Less than Significant. Odors may be generated from vehicles and/or equipment exhaust emissions during construction of the proposed Project. Odors produced during construction would be localized and attributable to concentrations of unburned hydrocarbons from tailpipes of construction equipment. Such odors are temporary and generally occur at magnitudes that would
Page 37 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 not affect substantial numbers of people in the vicinity of the construction area. As described above, and included in MM REC-1, trail users in the vicinity of the South Dike would be redirected around the construction area during active construction activities, limiting the potential for exposure to noticeable or objectionable odors. Therefore, impacts associated with odors during construction would be considered less than significant.
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4.4 Biological Resources
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, policies or regulations, or by the California Department of Fish and Wildlife or U.S. Fish and Wildlife Service? b) Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies or regulations, or by the California Department of Fish and Wildlife or U.S. Fish and Wildlife Service? c) Have a substantial adverse effect on federally protected wetlands, as defined by Section 404 of the Clean Water Act (including, but not limited to, marsh, vernal pool, coastal wetlands, etc.), through direct removal, filling, hydrological interruption or other means? d) Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established
native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites?
Page 39 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated e) Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance? f) Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community
Conservation Plan, or other approved local, regional or state habitat conservation plan?
4.4.1 Existing Setting
Regionally, the topography in this area consists of rolling to steep hillsides traversed by the Sweetwater River, which is a predominant natural feature of the Sweetwater CPA. Most of the original vegetation of the area has been modified by surrounding development; however, coastal mixed chaparral and coastal sage scrub exist on undeveloped hilly terrain and steep slopes (County of San Diego 2011b). Further, isolated remnants of riparian woodland dominated by sycamores and willows lie within the Sweetwater River channel between Central and Bonita Roads. These vegetation communities provide habitat for a variety of indigenous wildlife species. The riparian areas within the Sweetwater CPA are incorporated into the MSCP for the least Bell’s vireo (County of San Diego 2011b). Although some recently acquired smaller parcels are located within the MSCP area, most Authority-managed lands at Sweetwater Reservoir are not located in the MSCP area. Conduit Road passes through the MSCP area south of the dam.
The Project site is located at the southwestern end of a wide relatively flat valley, partly inundated by the Sweetwater Reservoir. The Project site ranges from the steep-walled narrows of the Sweetwater River associated with the Sweetwater Dam, to more gently sloped areas associated with the South Abutment Access Road and the South Dike. Between the months of January and June 2017, Amec Foster Wheeler conducted a biological resources assessment which included two initial field surveys, vegetation mapping, and a jurisdictional wetland delineation (see Attachment B). All undeveloped areas of the Project site were surveyed including the Sweetwater Dam, South Spillway, South Abutment Access Road, South Dike, and associated construction staging areas. Additionally, Conduit Road, which is located downstream of the dam and would be used for construction materials and concrete delivery, was also surveyed. During the surveys Amec Foster Wheeler biologists surveyed the Project site for special status plant and wildlife species and habitats necessary to support such species. The results of the two initial field surveys associated with the biological resources assessment indicated the presence of rare plants and potential habitat for Quino checkerspot butterfly (Euphydryas editha quino). Consequently, Amec Foster Wheeler conducted three focused rare plant surveys in the spring and summer of 2017, which coincided with the blooming period associated with the rare plants with high potential to
Page 40 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 occur within the Project area. Consistent with the USFWS Quino Checkerspot Butterfly Survey Guidelines (December 2014) Amec Foster Wheeler also conducted weekly surveys for Quino checkerspot butterfly during the 2017 survey season through mid-May 2017 (see Table 1 in Attachment B). Focused surveys for coastal California gnatcatcher and least Bell’s vireo were conducted by the Authority in 2017.
Vegetation
During the biological resources assessment, vegetation communities within the Project area were identified, mapped, and assessed for habitat value. Vegetation in the Project area includes native and nonnative communities, with disturbed or developed areas associated with reservoir infrastructure. As described in more detail in Attachment B, a total of 177 plant species were detected during the surveys, including 73 nonnative species. Vegetation communities include native grassland, nonnative grassland, riparian woodland/scrub, coastal sage scrub, eucalyptus/nonnative woodland, and disturbed/ruderal vegetation. Other mapped designations include open water/reservoir, existing facilities/managed areas, and sedimentation/drainage basin as well as a small patch of Arundo (see Table 4; see Figure 4 in Attachment B, which depicts the vegetation communities throughout the survey area, including the Project site).
Table 4. Vegetation Communities and Habitats in the Survey Area Vegetation Community Acres Native Grassland 0.18 Nonnative Grassland 7.11 Riparian Woodland/Scrub 0.61 Coastal Sage Scrub 4.34 Eucalyptus/Nonnative Woodland 2.42 Disturbed/Ruderal Vegetation 8.40 Open Water/Reservoir 7.26 Existing Facilities and Maintained Areas 13.57 Sedimentation/Detention Basin 0.79 Arundo Patch 0.03 Total 44.71 Notes: This table includes the total area of each vegetation community within the entire survey area, which includes the Project work area. See Figure 4 in Attachment B for complete vegetation survey results and mapping.
Nine special status plant species were detected in the survey area during the initial habitat assessment and focused rare plant surveys: decumbent goldenbush (Isocoma menziesii var. decumbens), Otay tarplant, Munz’s sage (Salvia munzii), San Diego sunflower (Bahiopsis laciniata), singlewhorl burrobrush (Ambrosia monogyra), small-flowered morning glory (Convolvulus simulans), snake cholla (Cylindropuntia californica var. californica), southwestern spiny rush (Juncus acutus ssp. leopoldii), and vernal barley (Hordeum intercedens), each of which are listed in the California Rare Plant Rank (CRPR) Inventory that is maintained by the California Native Plant Society (CNPS).
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Decumbent goldenbush (CRPR 1B.2) is a perennial low-growing shrub with a gray, hirsute appearance to the foliage. The flowers, which bloom from April – November, are bright yellow with rayless heads. A patch of 17 individuals was noted on and above the South Abutment Access Road on the lower slopes of the hill in coastal sage scrub (see Figure 4b in Attachment B).
Munz’s sage (CRPR 2B.2) is a perennial evergreen that occurs frequently below 1,640 feet elevation in coastal sage scrub in the south foothill and coastal region of San Diego County. Its blooming period is February – April. This species occurs in coastal sage scrub west of the SR- 125 bridge crossing in the areas of higher quality coastal sage scrub.
Otay tarplant (Federally and State Threatened; CRPR 1B) is a federally and state threatened species that often occurs in open disturbed areas on coastal plains, mesas, and river bottoms with coastal scrub, and valley and foothill grassland habitats with clay soil from approximately 80 to 990 feet in elevation. Federally designated critical habitat for the species encompasses most of the survey area with the exception of the open waters of the reservoir and developed facilities. A small patch of 13 plants was detected in close proximity to clustered tarweed (Deinandra fasciculata) on the west Otay tarplant is a federally and state side of the proposed borrow area south of the South Dike listed threatened plant species that was identified in the borrow area in disturbed habitat. Clustered tarweed is far more located to the south of the South Dike. common in all but the nonnative grasslands along the The individuals in this location would south shore of the reservoir. A historic population is also be impacted by the removal of fill from known from the disturbed habitat located between the the borrow area during construction former Taylor Residence and the South Dike (RECON activities associated with the proposed 2002). Project.
San Diego sunflower (CRPR 4.3) is a perennial shrub with yellow flowers that blow in the spring (January – July). This species occurs in southern San Diego County and northwestern Baja California. This species occurs throughout much of the coastal sage scrub in the survey area including along the South Abutment Access Road, north of the dam, and along Conduit Road.
Singlewhorl burrobrush (CRPR 2B.2) is a perennial shrub that occurs in sandy soil in chaparral, sage scrub, and Sonoran desert scrub. Its blooming period is August – November. A few individuals of this species were detected west of the SR-125 bridge crossing along the shoulder of Conduit Road, approximately 0.25 mile east of the dam.
Small-flowered morning-glory (CRPR 4.2) is an annual herb that occurs in clay soils and serpentine seeps in chaparral openings, coastal scrub, and grassland. Its blooming period is March – July. This species occurs in nonnative grassland on a slope east of the sedimentation/drainage basin located immediately to the south of the South Dike.
Page 42 LEGEND SCALE IN FEET N Project Boundary (Work Area) 0 1,000 Realigned Trail Segment Critical Habitat Coastal California gnatcatcher Otay tarplant Spreading navarretia
Service Layer Credits: Sources: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus, DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community P age 43 FIGURE Federally Designated Critical Habitat 8 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Snake cholla (CRPR 1B.1) is a perennial stem succulent known to occur in chaparral and coastal sage scrub habitat. One individual was found growing the under the South Bay Expressway overpass on Conduit Road in somewhat disturbed coastal sage scrub, in what is mostly a dense patch of San Diego County viguiera and black sage. Since this area was likely to have been revegetated/landscaped following highway and trail construction, it is possible that this was introduced. Snake cholla is known from the area, however, along the north shore of the reservoir.
Southwestern spiny rush (CRPR 4.2) is a perennial herb that typically occurs in alkaline meadows and seeps and moist coastal areas (e.g., dunes or marshes). Four individuals of spiny rush were found growing along the north side of the Conduit Road proposed access path in disturbed habitat/eucalyptus woodland.
Vernal barley (CRPR 3.2) is an annual grass that flowers from March – May. This grass was detected in the survey area along the Conduit Road proposed access pathway in disturbed, trailside habitat.
Additionally, two special status species have high potential to occur in the survey area: California adolphia (Adolphia californica) and San Diego barrel cactus (Ferocactus viridescens). However, these species were not detected within the survey area during the focused rare plant surveys. (See Attachment B for a detailed description of these special status plant species.)
Wildlife
During the two initial field surveys associated with the biological resources assessment Amec Foster Wheeler biologists recorded all wildlife species that were observed on-site or overhead. Methods of detection included direct visual observations, observation of wildlife sign (e.g., burrows, dens, scat, feathers, etc.), and listening for calls, as appropriate. As described in more detail in Attachment B, a total of 37 wildlife species where detected during the surveys, including 8 mammals and 29 bird species. Six of the species detected during the surveys are considered sensitive species including the coastal California gnatcatcher, coastal cactus wren (Campylorhynchus brunneicapillus sandiegensis), grasshopper sparrow (Ammodramus savannarum), least Bell’s vireo, northern harrier (Circus cyaneus), and San Diego black-tailed jackrabbit (Lepus californicus bennettii), which are California Species of Special Concern.
Coastal California gnatcatcher (Federally Threatened; California Species of Special Concern) is a small resident insectivorous bird species whose occurrence is strongly associated with the sage scrub habitats found throughout Southern California and extending into northern Baja California, Mexico. Although gnatcatchers have a close association with sage scrub. Habitat destruction, fragmentation, and modification have led to this species’ decline (USFWS 1993). Loss of habitat to agriculture and urban development were leading challenges to conserving the species until the interval between 2003 and 2007 when widespread fires consumed one-third of the habitat in the U.S. range of the species that USFWS believed to be suitable for the coastal California gnatcatcher (USFWS 2010). The gnatcatcher breeding season extends from mid- February through mid-August, although earlier starts and later seasons have been observed (USFWS 1993). During the breeding season, territories range from 2 to 14 acres (USFWS 2010) and during the non-breeding season can be as big as 35 acres (Preston et al. 1998). Coastal California gnatcatcher is historically known from the survey area, and the species was detected
Page 44 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 aurally (i.e., by sound) from coastal sage scrub habitat throughout the survey area. Focused surveys identified eight breeding territories within and/or immediately adjacent to Project work areas (Authority 2017) (see Attachment B). All coastal sage scrub as mapped on the site is considered occupied by the species.
Coastal cactus wren (California Species of Special Concern) occupies coastal lowlands from the San Juan Creek drainage basin in Orange County south to the Colorado River drainage basin in extreme northwestern Baja California. This subspecies is found only in coastal sage scrub with extensive stands of tall prickly pear or cholla cacti. Once widespread in San Diego County, by 1990 it had been reduced to fewer than 400 pairs in about 55 colonies. Most of these are threatened by proposed developments, and most are doubtfully viable, as they consist of only one to four pairs. Coastal cactus wren have been historically reported from Sweetwater Dam vicinity. Potential habitat in the form of cactus thickets occur in the survey area within portions of the coastal sage scrub. A nesting pair currently resides within a few hundred feet of the South Abutment Access Road (Authority 2017) (see Attachment B) and an individual was detected forging in coastal sage scrub within the survey area.
Grasshopper sparrow (California Species of Special Concern) is restricted to native grassland habitat in San Diego County and is considered localized and generally uncommon. Grasshopper sparrow nests are hidden on the ground and screened from above. This species was detected in nonnative grassland habitat along Conduit Road.
Least Bell’s vireo (Federally and State Endangered) is a federally and state endangered species that occurs in riparian scrub habitat within the region. The least Bell’s vireo is a small, migratory songbird that breeds in Southern California and northwestern Baja California, Mexico from April-July. It nests and forages almost exclusively in lowland riparian woodland. This species is typically associated with willow, cottonwood, mulefat, or other riparian plant species, and often in areas with high structural diversity, including overstory trees and understory saplings and shrubs. Least Bell’s vireo has been reported historically from the riparian habitat below the dam, and could potentially occur in riparian habitat along Conduit Road. Other riparian habitat with potential for nesting occurs along the reservoir edge near the dam, and in a fringe of willow scrub emerging along the current shoreline. Riparian habitats below the dam to the Bonita Golf Course are known to support least Bell’s vireo. Two to three territories in this river reach have been recorded from surveys by the Authority in 2014, 2015, and 2016. Spring surveys performed in 2017 identified two active breeding territories in the same area (Authority 2017) (see Attachment B).
Northern harrier (California Species of Special Concern) is distributed throughout North America and breeds from northern Alaska and Canada, south into roughly the northern two-thirds of the western U.S., and the northern one-third of the eastern U.S. San Diego County lies at the southwest edge of the harrier's breeding range in North America. Northern harrier is fairly common winter visitor and rare and local summer resident in the coastal lowlands of San Diego County. Harriers breed in marshes and grasslands, and forage in grasslands, agricultural fields, wetlands, and open coastal sage scrub. Harriers have declined in California in recent decades but can be locally abundant where suitable habitat remains free of disturbance, especially from intensive agriculture. An adult female northern harrier was observed foraging in the South Dike portion of the survey area during the January site reconnaissance. Nonnative grassland habitats within the
Page 45 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 survey area provide foraging opportunities. However, the potential for nesting is considered to be low.
San Diego black-tailed jackrabbit (California Species of Special Concern) is a habitat generalist that occurs in open or semi-open habitats including sparse stands of coastal sage scrub, grasslands, agricultural fields, and disturbed areas. Black-tailed jackrabbits are strictly herbivorous, feeding on a wide variety of grasses, forbs, and shrubs. In San Diego, they can breed throughout the entire year. An individual was observed in the coastal sage scrub habitat near the South Abutment Access Road during one of the site surveys and the species could occur in coastal sage scrub throughout the survey area.
The survey area also provides suitable nesting habitat for a variety of avian species across the habitat types present. Nesting birds are protected by the Migratory Bird Treaty Act (MBTA) and similar provisions of the California Fish and Game Code. All vegetation, native or nonnative, as well as some of the structures (e.g. the dam), provides habitat that may be used for nesting.
The majority of survey area (east of the SR-125 crossing of Conduit Road) is located within the USFWS designated survey area for the Quino checkerspot butterfly; however, as described in Attachment B no individuals were detected during the 12 protocol surveys. Overall, the survey area supports a range of low quality and moderate quality Quino checkerspot butterfly habitat (see Attachment B).
Wetlands
During the biological resources assessment field surveys, Amec Foster Wheeler wetlands scientists completed a delineation of potentially jurisdictional waters of the U.S. This wetland delineation included a complete inspection of the entire Project site (see Figure 6 in Attachment B, which depicts all jurisdictional waters within the Project site). Open Water associated with the Sweetwater Reservoir was identified based on the 239-foot elevation mark considered by the USACE to be within federal jurisdiction on past projects (Authority 2017). Non-Wetland Waters were identified by channelized water flow routes from reservoir discharges at the Sweetwater Dam and the South Spillway, and small drainages entering the Sweetwater Reservoir from the surrounding hillsides. Arroyo willow (Salix lasiolepis) were observed inundated areas at the edge of the Sweetwater Reservoir. Reservoir levels fluctuate so these wetlands can be submerged with sufficient runoff entering the reservoir, by water transfer from Loveland Reservoir, or as imported water via the San Diego County Water Authority aqueduct. Further, these areas are also subject to annual mowing or clearing as part of ongoing reservoir maintenance, thus they are delineated in conjunction with the Open Waters of the reservoir. Additional areas of potential wetland hydrology included the Sweetwater River downstream of the Sweetwater Dam, which contained willow communities, but soils were limited to riprap channel areas only within the Project area. The drainage downstream of the South Spillway and the small drainages entering the Sweetwater Reservoir contained only upland vegetation communities including brome (Bromus hordaceus), giant oat (Avena fatua), and Russian thistle (Salsola tragus). Therefore, these drainages were determined to be Non-Wetland Waters.
Page 46 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.4.2 Discussion a. Less than Significant with Mitigation Incorporated. Implementation of the proposed Project would involve construction activities along the north and south ends of the dam and repair activities at the South Spillway that would a have limited potential to directly impact sensitive plant or wildlife species. As described in Section 4.12, Noise, construction-related noise impacts would be expected during construction; however, these impacts would be short-term and temporary. Additional activities under the proposed Project involving substantial grading activities would include development of construction staging areas and improvements to the South Abutment Access Road and South Dike. As these activities would result in the direct removal of vegetation, they could potentially result in direct impacts to sensitive plant species or the removal of potential habitat for sensitive species, including coastal California gnatcatcher and San Diego black-tailed jackrabbit.
Plants
As described in Table 3 of Attachment B, a total of 35 sensitive plant species have the potential to occur within the Project area that could be affected by the proposed Project. Nine special status plant species included in the CRPR Inventory maintained by the CNPS, were detected in the survey area during the focused rare plant surveys: decumbent goldenbush, Otay tarplant, Munz’s sage, San Diego sunflower, singlewhorl burrobrush, small-flowered morning glory, snake cholla, southwestern spiny rush, and vernal barley. With the exception of decumbent goldenbush and Otay tarplant, all other sensitive plant species within the survey area were detected outside of the footprint of the proposed improvements and would be avoided during construction activities. Further, unintentional (i.e., accidental) removal or impacts to undetected sensitive plants would affect an extremely small number of individuals. It would be expected that the species would revegetate after disturbance.
A population of decumbent goldenbush lies within the footprint of road improvements and widening required for the South Abutment Access Road (see Figure 7b in Attachment B). Approximately 0.02 acres of occupied habitat would be permanently impacted by the improvements to the South Abutment Access Road; however, this is only a small fraction of the overall population present at this location (0.17 total acres), the remainder of the plants in this location would be avoided. Therefore, overall impacts to this rare plant species would be less than significant.
The small patch of Otay tarplant on the west side of the proposed borrow area south of the South Dike would be removed as a result of the proposed Project. Avoidance of these 13 plants is unavoidable as they are located within the borrow area that is being used to excavate fill dirt. During consultation for the proposed Project under Section 404 of the Clean Water Act, USACE could include the upland species within their purview to address Project efforts on all listed species including Otay tarplant. However, if USACE does not agree to cover these upland under Section 7 consultation, a low effect Habitat Conservation Plan (HCP) would be prepared under the USFWS Section 10 program. With the implementation of all required permit conditions as well as the implementation of MM BIO-1 and MM BIO-3, requiring off-site restoration of Otay tarplant at a ratio of no less than 2:1, impacts to this federally and state threatened species would be less than significant.
Page 47 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Wildlife
As described in Table 4 in Attachment B, 20 special status wildlife species have the potential to occur within the Project area that could be affected by the proposed Project. Six special status wildlife species were detected during the surveys including coastal California gnatcatcher, coastal cactus wren, grasshopper sparrow, least Bell’s vireo, northern harrier, and San Diego black-tailed jackrabbit. Coastal sage scrub, which provides habitat for coastal California gnatcatcher, was observed along the north end of the dam within the proposed construction staging areas immediately adjacent to the dam. Additionally, coastal sage scrub was mapped to the south of the dam, in the vicinity of the South Spillway and South Abutment Access Road. Riparian habitats between the dam and the Bonita Golf Course are known to support least Bell’s vireo. Two to three territories in this river reach have been recorded from surveys by the Authority in 2014, 2015, and 2016 (Authority 2015, 2016b, and 2017, respectively). Although disturbed by invasive plant species, the Conduit Road supports species and structural assemblage that is considered suitable least Bell’s vireo habitat. Other riparian habitat with potential for nesting occurs along the reservoir edge near the dam, and in a fringe of willow scrub emerging along the current shoreline. Riparian habitats below the dam to the Bonita Golf Course are known to support least Bell’s vireo. Two to three territories in this river reach have been recorded from surveys by the Authority in 2014, 2015, and 2016. Spring surveys performed in 2017 identified two active breeding territories in the same area (Authority 2017) (see Attachment B).
Vegetation removal and grading would result in direct permanent impacts to approximately 0.32 acres of coastal California gnatcatcher habitat, primarily associated with the construction staging area and improvements to the South Abutment Access Road. Under MM BIO-4 all vegetation removal and grading activities under the proposed Project would be conducted between September 1 and February 15 to the maximum extent practicable in order to avoid the coastal California gnatcatcher nesting season. Additionally, implementation of the proposed Project would not directly affect federally designated critical habitat for coastal California gnatcatcher, which is located adjacent to the Project site and not within the limits of the construction work area (refer to Figure 8). Direct impacts to least Bell’s vireo would not be anticipated; however, heavy haul trucks and other heavy construction equipment would utilize Conduit Road to deliver construction materials and concrete to the base of the dam. These activities would have the potential to generate indirect disturbance in the adjacent suitable riparian habitat. Indirect impacts could include dust, noise, chemical pollutants, general human presence, and construction-related soil erosion and runoff, which could adversely affect biological resources over the short-term. While construction traffic along this route is expected to be sporadic in nature, it may overlap with the least Bell’s Coastal California gnatcatcher is a federally vireo nesting season. Localized construction where threatened species and California species noise could exceed regulatory limits (e.g. 60 dBA of Special Concern that occupies coastal Leq) during the nest season for both gnatcatcher and sage scrub habitat. Individuals were vireos would require additional attenuation (e.g., detected at the Project site during the installation of temporary noise screens or sound biological resources surveys in January 2017.
Page 48 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 barriers during construction adjacent to active nests) as determined by a qualified biologist.
An adult female northern harrier was observed foraging near the South Dike area during the January survey. The removal of nonnative grassland habitats within this area would remove a minor amount of potential foraging habitat for this species. However, the potential for nesting is low given maintenance practices that likely keep this vegetation low. Grasshopper sparrows and cactus wren have potential to nest within grassland and coastal sage scrub habitats on site, respectively. Impacts to these nesting birds would be reduced to less than significant levels with the implementation of MM BIO-1 and MM BIO-4, which would restrict vegetation clearing during the breeding season (i.e., February – August), or require pre-construction surveys to clear construction areas. San Diego black-tailed jackrabbit was observed in coastal sage scrub habitat near the South Abutment Access Road. However, the San Diego black-tailed jackrabbit is a habitat generalist that occurs in a variety of open or semi-open habitats including sparse stands of coastal sage scrub, grasslands, agricultural fields, and disturbed areas. While implementation of the proposed habitat could have temporary indirect impacts to the species (e.g., construction- related noise), implementation of the proposed Project would not be expected to result in direct long-term impacts.
In addition to the six sensitive wildlife species that were detected during the field surveys, three sensitive wildlife species known to occur in the vicinity of the Project area were determined to have high potential to occur within the Project area due to the presence of potentially suitable habitat: Quino checkerspot butterfly, which is a federally endangered species, and orange- throated whiptail (Aspidoscelis hyperythra) and pocketed free tailed bat (Nyctinomops femorosaccus), which are California Species of Special Concern. No Quino checkerspot butterflies were detected during the focused surveys; however, the survey area supports a range of low quality and moderate habitat for the species including areas of coastal sage scrub with high densities of long-stem golden yarrow (Eriophyllum confertiflorum). Habitats associated with orange-throated whiptail are open associations of chaparral, coastal sage scrub, and grasslands (see Attachment B). This subspecies is often found in washes, streams, terraces, and other sandy areas, typically with patches of brush and rocky hillsides. This species has been historically reported from within the vicinity of the dam area (see Figure 5 in Attachment B). Pocketed free tailed bat has been documented historically just north of the survey area (see Figure 5 in Attachment B) and large trees and structures associated with the dam such as the South Spillway have the potential to support roosting bats. Construction could result in indirect impacts to these species including noise, dust, increased human activity; however, with the implementation of MM BIO-1 and BIO-4 these indirect effects would have less than significant impacts on these species.
In addition to the removal of coastal sage scrub habitat in the vicinity of the dam, the proposed Project would remove a grove of eucalyptus trees (Eucalyptus sp.) located adjacent to the south of the dam in order to support the improvements to the South Abutment Access Road. These trees could provide nesting habitat for raptors and migratory birds protected under the federal MBTA as well as potential roosting habitat for sensitive bats including the pocketed free tailed bat. Additionally, native shrubs located within the Project area, such as lemonade berry (Rhus integrofolia), willows (Salix spp.) and scrub oak (Quercus berberidafolia) as well as the existing sycamore trees (Platanus racemosa) within and adjacent to the work areas could also support migratory passerine birds and serve as nesting sites. Construction could result in noise, dust, increased human activity, and other indirect impacts to nesting raptors, migratory bird species,
Page 49 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 and bats in the project vicinity. However, with the implementation of MM BIO-1 and BIO-4 impacts would be less than significant.
Biological Resources Mitigation Measures for (a) would include:
BIO-1. Biological monitoring, consistent with federal and state laws and regulations, shall be implemented during all phases of construction. Specifically monitoring shall include:
• A qualified biologist shall conduct a pre-activity survey of all terrestrial and aquatic work areas prior to disturbance for any sensitive plants (e.g., California adolphia, San Diego barrel cactus, etc.) and/or wildlife species (e.g., orange-throated whiptail, pocketed free tailed bat, etc.).
• In the event sensitive species are probable or documented on-site, a qualified biologist shall be present to monitor all construction activities. The biologist shall be notified for relocation of wildlife species in the work area if they do not leave on their own and are at risk of harm. Any wildlife mortalities will be immediately reported to the biologist for verification, documentation, and reporting. Similarly, any identified rare plants should be removed and translocated to the extent feasible. Alternatively, seed may be salvaged prior to construction to be used in post-construction revegetation.
• Work areas and access routes, including Conduit Road, shall be clearly delineated with flagging, rope, or construction fencing, and workers shall remain within defined Project boundaries. Signage for Environmentally Sensitive Areas should be installed and maintained.
• A qualified biologist shall provide project contractors and crews with a worker-awareness program before any work within the Project area.
• Vehicles and equipment shall be properly maintained to avoid hazardous spills. In the event of a minor release, spills shall be cleaned up immediately and contaminated soil shall be removed and disposed of at licensed and permitted facilities.
BIO-2. A habitat revegetation plan shall be developed by the Authority to describe methods for re-seeding and re- vegetating temporarily disturbed areas within sensitive habitats. Any temporary impacts caused by physical disturbance (e.g., trampling) of vegetation would be mitigated through on-site revegetation to pre-project conditions (or better) following construction. Permanent impacts to sensitive vegetation communities would be mitigated through the off-site conservation, restoration, enhancement, and/or management of similar habitats at a ratio of no less than 2:1 for coastal sage scrub and 1:1 for nonnative grassland. Existing eucalyptus trees at the south end of the dam could provide suitable BIO-3. Otay tarplant removed by the proposed Project nesting habitat for raptors and other shall be restored/enhanced off-site at a ratio of no less migratory birds.
Page 50 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 than 2:1 through any combination of the following: plant salvage and replanting, seed collection and dispersal, and/or container planting. Specifically, off-site restoration of Otay tarplant would occur within an approximate 20-acre conservation easement associated with the Sweetwater Reservoir Shoreline Fishing mitigation area. Approximately 13 acres of this area are preserved in place as non-native grassland, and therefore would benefit from Otay tarplant restoration and management. This conservation easement is located on the southwest shoreline of Sweetwater Reservoir, approximately 700 feet to the northwest of the South Dike. The Authority would monitor the establishment of the species and maintain If needed, a staging area will be this area (e.g., weed control) consistent with the established adjacent to the north abutment and below the 239-foot requirements of the conservation agreement with elevation, which is the reservoir’s high California Department of Fish and Wildlife (CDFW) and water mark elevation. USFWS.
BIO-4. To minimize coastal cactus wren impacts, any large specimen coast cholla directly impacted by the proposed Project shall be salvaged and replanted. Salvaged coast cholla should be replanted in the coastal sage scrub habitat adjoining the project site or other close receptor site.
BIO-5. Construction activities shall avoid nesting season and other breeding seasons, consistent with federal, state, and local guidance, to the extent feasible.
• Removal of vegetation shall occur outside of the nesting season for birds. Typically, this is January 15 to August 31 for large trees or wooded areas (i.e. for raptors), March 1 to September 15 for riparian and marsh associated birds, and February 15 to August 31 for upland scrub or grasslands birds. If unavoidable, a pre-construction nesting bird survey by a qualified biologist could determine if nesting birds are in the work area. Vegetation removal could occur if no active nests or nesting activity is found within or immediately adjacent to the project work area. Further, project activities shall not indirectly harm or preclude nesting bird activity (e.g., typically within 300 feet for passerine birds and 500 feet for raptors). If a nest is found, the type of construction activity would be evaluated and avoidance methods would be implemented as necessary. Methods would vary based on bird species, site conditions, and type of work to be conducted, but could consist of: limited or reduced construction access; reduced vehicle speeds; noise attenuation; and/or a no- work buffer zone placed around the nest until the adults are no longer using it or the young have fledged. Any buffer width would be determined by a qualified biologist at the time of discovery, and constraint measures would be monitored to evaluate effectiveness.
• Removal of vegetation from occupied coastal California gnatcatcher habitat (i.e. coastal sage scrub) between February 15 and August 31 is precluded by this project. As determined by biological monitoring during construction, access routes and active construction areas adjacent to nesting habitat for vireo and gnatcatcher may require
Page 51 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
additional buffers and noise attenuation during the nest season. These too would be evaluated and implemented by a qualified biologist prior to and during construction.
• A qualified biologist shall conduct preconstruction surveys for active bat roosts within 30 days and within 200 feet of disturbance activities where suitable roost habitat is present (e.g., trees, structures, bridges, rock formations). If an active maternity roost is located and the proposed Project cannot avoid removal of the occupied tree, demolition shall commence before maternity colonies form (i.e., before March 1) or after young are flying. Disturbance-free buffer zones as determined by a qualified biologist shall be delineated and observed during the maternity roost season (March 1-August 31).
BIO-6. All appropriate permits, including Section 404 NWP, Section 401 Water Quality Certification, Section 1602 LSAA, Federal incidental take permits, and CESA consistency determination shall be obtained prior to construction activities, which may include and compensation for impacted jurisdiction wetland and upland habitats, as necessary.
• Prior to the commencement of construction activities in jurisdictional wetlands, all appropriate federal and state permits shall be obtained, including Section 404 NWP, Section 401 Water Quality Certification, and Section 1602 LSAA, as applicable. Permit conditions would require mitigation of impacts to jurisdictional wetlands, other regulated waters of the U.S. or state, and/or riparian habitat under the jurisdiction of CDFW at an appropriate mitigation ratio negotiated with the relevant resource agencies.
• Permanent impacts to Non-Wetland Waters shall be mitigated at a 2:1 ratio through creation, restoration, or enhancement of aquatic or wetland habitat on Authority lands. The specific mitigation area shall be determined in coordination with the appropriate jurisdictional agencies (i.e., USACE, RWQCB, and CDFW, as necessary), but shall include restoration or enhancement in Sweetwater Reservoir HMP or riparian area below the Sweetwater Dam. The Authority shall restore the functions and values of habitats temporarily impacted by project activities at a 1:1 ratio to pre-project conditions. These restoration activities shall be addressed in a revegetation plan for the Project.
• To the extent required by the USFWS and CDFW under federal ESA and the California Endangered Species Act (CESA), native upland habitats (e.g., coastal sage scrub) shall be mitigated or otherwise compensated for (e.g., conservation banks) at an appropriate mitigation ratio. b, c. Less than Significant with Mitigation Incorporated. In general, sensitive habitats include: areas of special concern to resource agencies; areas where impacts could be potentially considered significant under CEQA thresholds; areas designated as sensitive natural communities by CDFW; areas outlined in Section 1600 of the California Fish and Game Code; and areas regulated under Section 404 of the federal Clean Water Act.
As a part of the biological resources assessment, sensitive habitats within the Project area were surveyed and mapped. Sensitive habitats located within the Project site include coastal sage scrub, nonnative grassland, and riparian habitats, each of which have potential to support sensitive species as described above. Permanent impacts from construction would be limited to 0.32 acres of coastal sage scrub required for the improvements to the South Abutment Access Road and 1.16 acres of nonnative grassland required for improvements to the South Abutment Page 52 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Access Road and the South Dike. Native grassland and riparian woodland habitats within the study area are avoided. Other temporary impacts to nonnative or disturbed vegetation would occur as a result of minor trampling from construction equipment (see Figure 9 and 10; see Figure 7 in Attachment B, which depicts all of the vegetation impacts within the Project site). However, since these areas would not be directly removed and would not be graded or developed, temporary impacts would not diminish these vegetation communities over the long-term.
Overall, implementation of the proposed Project would result in permanent impacts to a total of 5.98 acres including 0.32 acre of native coastal sage scrub habitat and 1.16 acres of nonnative grassland (see Table 5; see Figure 7 in Attachment B, which depicts all of the permanent and temporary impacts to vegetation at the Project site). With the implementation of MM BIO-1 and BIO-2, impacts to these sensitive vegetation communities would be less than significant.
Table 5. Impacts to Land Cover and Vegetation Communities Permanent Temporary Total Impacts Vegetation Community Impacts (acres) Impacts (acres) (acres) Coastal Sage Scrub 0.32 0 0.32 Native Grassland 0 0 0 Riparian Woodland/Scrub 0 0 0 Disturbed/Ruderal Vegetation 1.16 2.92 4.08 Eucalyptus/Nonnative Woodland 0.24 0.01 0.25 Existing Facilities/Managed Areas 3.04 2.95 5.99 Nonnative Grassland 1.16 1.83 2.99 Sedimentation/Drainage Basin 0.02 0.09 0.11 Open Water/Reservoir 0.04 1.40 1.44 Total 5.98 9.20 15.18
Page 53 AREA OF DETAIL FEET Service Layer Credits: Sources: Esri, DeLorme, NAVTEQ, USGS, NRCAN, METI, iPC, ToTomTom mTo m N 01,500 Esri, HERE, DeLorme, MapmyIndia, © OpenStreetMap contributors Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA
Sweetwater Reservoir
DIST
Sweetwater Summit CSS Regional
CONDUIT ROAD Park CSS CSS 125 .! CSS .!
CSS
RIP
OW
LEGEND RIP Biological Resources Survey Area Access Route Project Impacts RIP RIP RIP Permanent RIP Temporary DEV
Vegetation Coastal Sage Scrub (CSS) CSS EUC CSS Disturbed/Ruderal Vegetation (DIST) CSS Eucalyptus/Non-native Woodland (EUC) EUC CSS CSS EUC Existing Facilities/Managed Areas CSS Open Water/ReservoirRIP (OW) Riparian Woodland Scrub (RIP) CSS Sensitive Species SCALE IN FEET San Diego viguiera (Bahiopsis lacinata) N Observation/Population 0180 P age 54 FIGURE Vegetation Impacts at the Dam 9 LEGEND SCALE IN FEET Vegetation N Biological Resources Survey Area 0 180 Realigned Trail Segment Coastal Sage Scrub (CSS) Disturbed/Ruderal Vegetation (DIST) Historic Otay Tarplant Population Eucalyptus/Non-native Woodland (EUC) Project Impacts Existing Facilities/Managed Areas Permanent Non-native Grassland (NNG) Temporary OW Native Grassland (NG) Open Water/Reservoir (OW) NNG Riparian Woodland Scrub (RIP) NNG Sedimentation/Drainage Basin (SED) NNG Vernal Pool (VP)
Sensitive Species Populations NNG DIST Small-flowered morning glory (Convolvulus simulans) DIST Otay tarplant (Deinandra conjugens) SED
NNG VP NNG DIST NNG
DIST DIST NNG DIST EUC NNG SED DEV DIST DIST NNG
FEET EUC N NG 01,500 CSS DIST Sweetwater RIP Reservoir
Sweetwater AREA OF DETAIL Summit Regional
CONDUIT ROAD Park
Service Layer Credits: Sources: Esri, DeLorme, NAVTEQ, USGS, NRCAN, METI, iPC, ToTomTom mTo m
Esri, HERE, DeLorme, MapmyIndia, © OpenStreetMap contributors 125 Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA Page Page
55 FIGURE Vegetation Impacts at the South Dike 10 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Waters likely considered to be jurisdictional to the USACE, Regional Water Quality Control Board (RWQCB), and CDFW include Open Water, Non-Wetland Waters, and Wetlands as identified in Figure 6 in Attachment B. As described above, Open Water associated with the Sweetwater Reservoir was identified based on the 239-foot elevation mark considered by the USACE to be within federal jurisdiction on past projects (Authority 2017). Non-Wetland Waters under the jurisdiction of the RWQCB and CDFW were identified by channelized water flow routes from reservoir discharges at the Sweetwater Dam and the South Spillway, and small drainages entering the Sweetwater Reservoir from the surrounding hillsides.
Impacts to Non-Wetland Waters would generally result from the repairs to the South Spillway, which is located adjacent to the reservoir and improvements to the South Abutment Access Road. Additionally, the depressions located to the south of the South Dike are considered Non-Wetland Waters under the jurisdiction of RWQCB and CDFW. Consequently, improvements to the South Dike would result in permanent fill of a portion of these areas within the proposed footprint of the dike.
Overall, the proposed project would permanently fill and impact and 0.04 acres of Open Water and 0.22 acres of Non-Wetland Waters. Impacts to Open Water would be limited to the small shoreline area below the 239-foot elevation contour adjacent to the concrete spillway and South Abutment Access Road. Actual Open Water behind the dam would not be affected by the proposed Project. The majority of the permanent impacts to Non-Wetland Waters, would be to the existing concrete lined spillway of the Sweetwater Dam (see Table 6, Figure 11 and 12; also see Figure 8 in Attachment B, which depicts all of the impacted areas within the Project site). Additionally, temporary impacts (i.e., where the topography and drainage would not change following the completion of construction activities) could affect up to 1.31 acres of Open Water and 0.09 acre of Non-Wetland Waters. As shown in Figure 11, shoreline areas delineated as jurisdictional Open Water of the reservoir (below the 239-foot contour), would be used for temporary equipment and materials staging for dam improvements. Only those areas above the water level at the time of the work would be utilized for this purpose. Work on the South Dike would require temporary disturbance to dry portions of the adjacent shoreline of the reservoir and sedimentation basin for access to the dike structure.
Table 6. Impacts to Jurisdictional Waters Permanent Temporary Total Impacts Jurisdictional Waters Impacts (acres) Impacts (acres) (acres) Open Water 0.04 1.31 1.35 Non-Wetland Waters of the U.S. 0.05 0.09 0.14 Non-Wetland Waters of the U.S. - 0.17 NA 0.17 Spillway Total 0.26 1.40 1.66
The proposed Project would require Section 404 NWP, 401 Water Quality Certification, and 1602 LSAA. Adherence to the permit conductions and mitigation requirements in these permits and as specified in MM BIO-6, would result in less than significant impacts to wetland habitats within the Project site.
Page 56 AREA OF DETAIL FEET Service Layer Credits:Credits: Sources: Esri, DDeLorme,eLorme, NAVTEQ,NAVTEQ, USGS, NRCAN, METI,METI, iPCiPC,, TomTom N 01,500 Sources:Sources: Esri,Esri, DigitalGlobeDigitalGlobe,, GeoEye,GeoEye, Earthstar Geographics,Geographics, CNES/Airbus DS,DS, USDA, USGS,USGS, AeroGRID,AeroGRID, IGN,IGN, andand the GISGIS User Community
Sweetwater Reservoir
Sweetwater Summit Regional
CONDUIT ROAD Park
125
LEGEND Biological Resources Survey Area 239 Foot Contour
Project Impacts Permanent Temporary
Jurisdiction USACE/RWQCB/CDFW Open Water SCALE IN FEET N Non-Wetland Waters 0180 P age 57 FIGURE Impacts to Jurisdictional Waters at the Dam 11 FEET SCALE IN FEET N 01,500 N 0 180 Sweetwater Reservoir
Sweetwater AREA OF DETAIL Summit Regional
CONDUIT ROAD Park
125
LEGEND Biological Resources Survey Area 239 Foot Contour Realigned Trrail Segment
Project Impacts Permanent Temporary
Jurisdiction USACE/RWQCB/CDFW
Service Layer Credits:Credits: Sources: Esri, DDeLorme,eLorme, NAVTEQ,NAVTEQ, USGS, NRCAN, METI,METI, iPCiPC,, TomTom Open Water Sources:Sources: Esri,Esri, DigitalGlobeDigitalGlobe,, GeoEye,GeoEye, Earthstar Geographics,Geographics, CNES/Airbus DS,DS, USDA, USGS,USGS, AeroGRID,AeroGRID, IGN,IGN, aandnd the GIGISS User Community Non-Wetland Waters Page Page
58 FIGURE Impacts to Jurisdictional Waters at the South Dike 12 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 d. Less than Significant. Wildlife corridors include both local movement routes and regional corridors and linkages. Local movement routes often connect resources on a localized level, often on a daily or nightly basis, such as water sources, foraging areas, and den/cover sites. Regional movement corridors or linkages connect larger patches of open space and are important to wildlife for seasonal movements, and for the long-term genetic flow between subpopulations. For large mammals, regional corridors are often required to provide a network of large scale foraging or hunting areas. Corridors can be continuous habitat features, or “stepping stones” such as rest areas along a bird migration route. Corridors often follow linear topographical, water, or vegetation features. The Project area, including the Sweetwater Reservoir, forms an east-west connection between the coast and open space areas of the southeastern San Diego County. The Project area is situated within a segment of this east-west corridor as well as an area that connects open space areas to the north and south on a local level and is potentially a local water access route for species in the surrounding habitats. However, as described above, permanent impacts resulting from the proposed Project would be limited to 5.98 acres, of which only 0.32 acre would be native habitats. Temporary impacts would affect nonnative habitats and developed areas, all of which will be able to provide a similar function within the wildlife corridor following the completion of the proposed Project. Additionally, the proposed Project would not include the construction of any new linear elements that would preclude wildlife movement. Therefore, impacts to the Project area would be considered an incremental loss of habitat, but would not be considered a significant impediment to wildlife movement. The proposed Project would not affect the overall function of this area as a wildlife corridor and impacts would be less than significant. e. Less than Significant. The County’s policy framework contains several policies relating to the conservation and protection of biological resources, including the MSCP, Resource Protection Ordinance, Biological Mitigation Ordinance, and Habitat Loss Permit Ordinance. Sweetwater Reservoir lands are not part of the San Diego County MSCP. The Authority is a Special District within the boundaries of the Sweetwater Reservoir Property and is not subject to local land use plans, policies and ordinances. Nevertheless, the Authority strives to be consistent with local plans or ordinances when proposing and implementing projects. A portion of the Conduit Road construction route access passes through County Park boundaries, which is included in the MSCP. However, this road will only be used for sporadic construction access (e.g., concrete truck). As such, minor indirect impacts related to noise would be short-term and temporary and no direct impacts to MSCP lands are anticipated. Therefore, implementation of the proposed Project would not conflict with the MSCP and impacts would be less than significant.
The Authority established a Habitat Management Program (HMP) within the footprint of a historic sand mining lease in the upper reservoir. The Authority terminated the lease in the 1980s and developed the HMP in the 1990s as a means to balance protection of the federally and state endangered least Bell’s vireo with water quality and water storage objectives. A managed reservoir area to be cleared of vegetation was delineated, as well as a preserve area to be revegetated and managed to protect and enhance habitat for the vireo and associated wildlife. Within the HMP preserve, surplus restored riparian habitat approved by the USFWS, USACE, and CDFW is available for mitigation of Authority projects. The enhancement and revegetation measures described under MM BIO-3 could also sufficiently mitigate permanent and temporary impacts to jurisdictional areas. As such, implementation of the proposed Project would not conflict with the Authority’s HMP.
Page 59 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 f. Less than Significant. Natural Community Conservation Plans (NCCPs) are state-sponsored programs endorsed by the federal government to balance the needs of urban development and economic growth with species and habitat protection. NCCPs employ a multi-habitat and multi- species conservation planning approach, focusing on preserving the largest core habitat areas possible while protecting necessary habitat linkages and wildlife movement corridors that are necessary to maintain long-term biological and genetic diversity. The proposed Project is not located within an approved NCCP or Habitat Conservation Plan (HCP) area. Sweetwater Reservoir lands are not part of the San Diego County MSCP. As described above, a portion of the Conduit Road construction route access passes through County Park boundaries, which is included in the MSCP. However, this road will only be used for sporadic construction access (e.g., concrete truck). As such, minor indirect impacts related to noise would be short-term and temporary and no direct impacts to MSCP lands are anticipated.
Page 60 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.5 Cultural Resources
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Cause a substantial adverse change in the significance of a
historical resource as defined in §15064.5? b) Cause a substantial adverse change in the significance of an
archaeological resource pursuant to §15064.5? c) Directly or indirectly destroy a unique paleontological resource
or site or unique geological feature? d) Disturb any human remains, including those interred outside of formal cemeteries?
4.5.1 Existing Setting
Phase I Cultural Resources Study
Amec Foster Wheeler conducted a Phase I Cultural Resources Study for the Project site, which included historical background research, an archaeological and historical resources records search, consultation with the Native American Heritage Commission (NAHC), and a Phase I pedestrian field survey (Amec Foster Wheeler 2017). The Phase I Cultural Resources Study covered approximately 30.62 acres of developed and semi-developed land within the Project area at the Sweetwater Reservoir. The South Coastal Information Center (SCIC) records search indicated that 21 cultural resource investigations have been completed within the Project area and a total of 98 cultural resource studies have been conducted outside of, but within 1 mile of the Project area. In addition to the records search at the SCIC, the California Office of Historic Preservation was consulted for all National Register of Historic Places (NRHP) and California Register of Historic Resources (CRHR) listings within the 1-mile search radius; however, no listings were found in the search radius. As described in the Phase I Cultural Resources Study, a total of 36 cultural resources have been previously recorded within a 1-mile radius of the Project area (Amec Foster Wheeler 2017).
Previously Recorded Cultural Resources in the Project Vicinity
Previously recorded cultural resources identified outside of the Project area, but within a 1-mile radius, include prehistoric habitation and camp sites, hunting blinds, quarry sites; lithic, marine
Page 61 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 shell, ceramic and groundstone scatters; milling stations, hearths and rock alignments. Historic- era cultural resources within 1 mile of the Project area include historic buildings, a church, remnants of the National City and Otay Railroad and historic bottle glass fragments (Amec Foster Wheeler 2017).
Archaeological Resources at the Project Site
An intensive field survey of the Project area was conducted by Amec Foster Wheeler senior archaeologist Jesse Yorck, RPA on January 27, 2017. The majority of the surface sediments within the Project area are rocky silt loam variants. As described in the Phase I Cultural Resources Study the entire Project area has been mechanically altered (through grading, excavation, inundation and stockpiling) by construction and maintenance activities related to the Sweetwater Dam, South Spillway, South Dike, and the associated roads and trails. The ground surface was visually inspected for any signs of human use dating to more than 50 years old. Areas with disturbed or exposed soils were particularly scrutinized for indications of cultural materials. Modern trash including milled wood fragments and non-diagnostic, rusted metal objects were encountered; however, these items did not have historic or archaeological value. No new cultural resources were identified during the field survey. The previously documented Sweetwater Dam (Site 37-016325), including the dam, spillways, and South Dike was the only potentially historic resource identified located within the Project site. Site 37-016325 was last documented in 1998 and recommended eligible for the NRHP (Mikesell 1998).
Sweetwater Dam
Pursuant to the National Historic Preservation Act (NHPA) of 1966, the National Park Service has established eligibility criteria for the NRHP. A resource may be eligible for listing in the NRHP if the quality of significance in American history, architecture, archaeology, engineering, and culture is present in districts, sites, buildings, structures, and objects that possess integrity of location, design, setting, materials, workmanship, feeling, and association and:
a) that are associated with events that have made a significant contribution to the broad patterns of our history; or b) that are associated with the lives of persons significant in our past; or c) that embody the distinctive characteristics of a type, period, or method of construction, or that represent the work of a master, or that possess high artistic values, or that represent a significant and distinguishable entity whose components may lack individual distinction; or d) that have yielded, or may be likely to yield, information important in prehistory or history. (36 Code of Federal Regulations [CFR] § 60.4)
The Sweetwater Dam was originally recorded and evaluated as part of the Historical Resource Evaluation for Sweetwater Dam, National City and Otay Railroad (NC&O) Sweetwater Branch, and Sweetwater Quarries (Mikesell 1998). The dam is considered eligible for the NRHP under Criteria A and C. Its significance stems from its importance as a composite structure illustrating how a marginal, largely reconstructed dam was transformed into a safe and useful structure that provided drinking water to the San Diego region (Mikesell 1998). Its period of significance begins
Page 62 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 when the dam took on its present appearance, in 1917, and ends when the dam’s significance as a source of drinking water to the region was drastically diminished in 1940 (Mikesell 1998). The historical integrity of the dam stems from its appearance dating to 1911; the central core, abutments and spillways dating to 1917 were assessed based on its expansion and reconstruction after the 1916 flooding event, which extensively damaged the Sweetwater Dam. These character-defining features that were constructed in 1917 contribute to the dam’s appearance and overall historical integrity as they are representative of how a marginal, largely reconstructed dam was transformed into a safe and useful structure. Although not listed on the NRHP, the Sweetwater Dam, including the dam itself, the South Spillway, and the South Dike, are eligible for listing and as such are considered an historic property under NHPA. Further, and as resources in California determined eligible for the NRHP are automatically listed in or determined eligible for the CRHR, the Sweetwater Dam is also considered a historical resource, meeting Criteria 1 and 3 of the CRHR, pursuant to CEQA.
The Sweetwater Dam (Site 37-016325) was recorded and evaluated in 1998 and recommended eligible for the NRHP under Criteria A and C, however it is not currently listed on the NRHP or CRHR.
The original dam was constructed of granite porphyry from local mines in 1888. It rose 90 feet and spanned 340 feet, the highest in U.S. history at the time. With the incoming NC&O Railway, the Sweetwater Dam brought commerce to the area and enabled the transformation of the Sweetwater Valley into a major citrus production and farming center of San Diego County. The dam was structurally altered in 1911 from its masonry arch structure to its current structure as a gravity arch dam. Originally designed by the San Diego Land and Town Company, designer and construction supervisor James D. Schuyler oversaw the project. Utilizing updated materials and construction methods, JD Schuyler and HN Savage transformed the dam to develop safe and dependable means of storing water in 1911. After 1911, the dam was transformed both in structural type and in appearance from a masonry arch structure to a gravity arch dam. Mikesell notes that most of the original aspects of the dam are “invisible” (i.e., covered by later concrete additions). Its architect, JD Schuyler, notes that the masonry arch structure was an engineering
Page 63 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 piece of artwork for its time, bringing tourism and notoriety to the Sweetwater River. Tourism trains, called “Dam Trains,” were promoted by the San Diego Land & Town Company, then owner of the NC&O Railroad.
Several alterations have been made to the dam’s structure following its original construction (Mikesell 1998). In 1911, the height was increased to 240 feet and in 1917 to elevation 253 feet. In 1939-1940 the central segment parapet was cut to elevation 235 feet making the central portion of the dam 18 feet lower than the parapet on the spillways. In 1917, the north spillway was constructed of reinforced concrete extending about 140 feet long along the crest. The South Spillway includes elements of work from 1888, 1911, and 1917. The south abutment was rebuilt in 1992, but still contains an 1889 tunnel that was lined with concrete in 1987. The stilling basing was built in 1917 of reinforced concrete, and rests downstream roughly 300 feet from the foot of the main dam. The stilling basin was designed to catch and calm waters from the spillways. The intake tower, located midway along the crest of the dam, was built in 1888 and rehabilitated in 1989, which included the construction of a new roof. The South Dike was constructed in 1911, failed in 1916 during a flooding event, and was repositioned and rebuilt in 1917. Several other modifications have taken place over the years including removing much of the parapet in 1940, and south parapet partial reconstruction in 1992. Even after the various additions, modifications, and repairs, the Sweetwater Dam and its appurtenant structures are still considered eligible for the NRHP under Criteria A and C (Mikesell 1998).
4.5.2 Discussion a. Less than Significant. The Phase I Cultural Resources Study did identify resources, as defined by CEQA, which include the previously documented features of the Sweetwater Dam, which has been evaluated and recorded as a NRHP-eligible site (Site 37-016325) (Amec Foster Wheeler 2017). The dam is comprised of several structural elements, which include the dam itself, the intake tower, the spillways, the stilling pool dam, and the South Dike. Under the proposed Project, the north and south parapet walls of the dam would be raised. However, the original parapets were removed in 1940 and the south parapet was partially reconstructed in 1992. As such, the parapet walls do not fall within the period of significance for the NRHP-eligible resource. Both the north and south parapets are currently modern in appearance and do not retain historic integrity or otherwise substantially contribute to the dam’s historical significance. Additionally, the height increase associated with the proposed parapets (i.e., 6.7 feet at the north end of the dam and 1.7 feet at the south end of the dam) would be minor.
Repairs to the South Spillway would not impact the dam’s appearance in any significant way, and the concrete used for in-kind repairs to cracking, spalling, and otherwise deteriorated concrete would match the existing concrete already in place. The proposed Project would not alter any characteristics of the South Spillway in a manner that would diminish the Sweetwater Dam’s integrity of location, design, setting, materials, workmanship, feeling or association (36 CFR § 800.5). These improvements would be a continuation of engineering efforts which have made the dam an example of a composite structure dam, and would not diminish its historic role in providing drinking water to the region. Further, repair of the South Spillway would meet the Secretary of the Interior’s Standards for the Treatment of Historic Properties (36 CFR § 68.3):
Page 64 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
“Where the severity of deterioration requires repair or limited replacement of a distinctive feature, the new material will match the old in composition, design, color and texture” (36 CFR § 68.3[a][6]).
Therefore, repair of the South Spillway would not materially impair the significance of the Sweetwater Dam, nor would it alter those qualities which make the resource eligible for listing in the NRHP and CRHR. As provided for under CEQA Guidelines Section 15064.5(b)(3), generally, a project that follows the Secretary of the Interior's Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring, and Reconstructing Historic Buildings, shall be considered as mitigated to a level of less than a significant impact on the historical resource.
The Project would also follow the Secretary of the Interior’s Standards for Treatment of Historic Properties (36 CFR § 68.3) as it would entail the addition of in-kind earthen material to the South Dike, which is a normal and ongoing aspect of levee safety and capacity compliance. The character, purpose and appearance of the South Dike would not be substantially altered in a way that would diminish its role as a contributing element to the Sweetwater Dam. The Project would consequently have a less than significant impact on the South Dike for the purposes of CEQA (14 California Code of Regulations [CCR] § 15126.4).
Overall, the proposed Project would not cause a substantial adverse change to any historical resources within the Project area or the vicinity of the Sweetwater Reservoir. b, c. Less than Significant with Mitigation Incorporated. A total of 36 cultural resources have been previously recorded within a 1-mile radius of the Project area, including prehistoric habitation and camp sites, hunting blinds, quarry sites; lithic, marine shell, ceramic and groundstone scatters; milling stations, hearths and rock alignments. Also listed were three unidentified isolates within a mile of the Project area. Given the results of previous archaeological studies in the area of potential effect (APE) vicinity and the proximity of previously documented resources, the prehistoric and historic archaeological sensitivity of the APE vicinity appear to be high. However, the Project area has been extensively disturbed by previous activities associated with construction and maintenance activities related to the Dam, the South Dike and the associated roads and trails.
Additionally, no new cultural resources were identified during the field survey and the previously documented Sweetwater Dam (Site 37-016325), including the dam, South Spillway, and South Dike, comprises the majority of the Project area. However, the proposed Project would involve ground-disturbing activities that could extend into undisturbed soil; such actions could potentially unearth, expose, or disturb previously unknown subsurface historical, archaeological, paleontological, or Native American resources that were not reported or observable on the surface. Resources that may be encountered may include buried architectural elements such as foundations or walls, and historic-era artifacts relating to the construction and operation of the dam.
If historic, archaeological, or paleontological resources are discovered during construction activities, implementation of MM CUL-1, CUL-2, and CUL-3 would reduce potential impacts to less than significant levels. Therefore, it is anticipated that impacts would be potentially significant unless mitigation is incorporated.
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Cultural Resources Mitigation Measures for (b, c)
CUL-1. Prior to the initiation of ground-disturbing activities, qualified archaeological and paleontological monitors shall be retained and shall provide a “tailgate” presentation to construction workers prior to grading associated with the South Abutment Access Road. The presentation shall describe potential archaeological deposits that could be may be encountered during construction activities. The monitors shall be present during the first day of grading activities and shall make recommendations on subsequent monitoring based on observations during that initial phase.
CUL-2. If an archaeological deposit or resource is encountered during grading activities, all activity in the vicinity of the find shall cease until it can be evaluated by a qualified archaeologist, defined as one meeting the Secretary of the Interior’s Professional Qualification Standards for archaeology. If the find is determined to be potentially significant, the archaeologist, in consultation with the Authority and appropriate Native American group(s) (if the find is a prehistoric or Native American resource), shall develop a treatment plan. All work in the immediate vicinity of the unanticipated discovery shall cease until the qualified archaeologist has evaluated the discovery, or the treatment plan has been implemented.
CUL-3. If paleontological resources are encountered during the course of construction and monitoring, the Authority shall halt or divert work and notify a qualified paleontologist who shall document the discovery as needed, evaluate the potential resource, assess the significance of the find, and develop an appropriate treatment plan in consultation with the Authority. d. Less than Significant with Mitigation Incorporated. The NAHC was contacted on January 30, 2017 to determine if there was a presence of cultural sites within or immediately adjacent to the APE. The NAHC responded on March 10, 2017 that there are no known Native American resources within the Project area. As such, it is highly unlikely that the proposed Project would disturb known human remains. The land use designations for the proposed Project components do not include cemetery uses, and no known human remains exist at the Project site. While highly unlikely, if Native American resources or human remains are discovered during construction activities, implementation of MM CUL-4 would reduce potential impacts to less than significant levels.
Cultural Resources Mitigation Measure for (d)
CUL-4. Consistent with CEQA Guidelines Section 15064.5(e), if human remains are accidentally discovered or recognized during construction excavation and grading activities, State Health and Safety Code Section 7050.5 requires that no further disturbance shall occur until the County Coroner has made the necessary findings as to origin and disposition pursuant to Public Resources Code Section 5097.98. If the remains are determined to be of Native American descent, the coroner has 24 hours to notify the Native American Heritage Commission. The NAHC will then identify the person(s) thought to be the Most Likely Descendent of the deceased Native American, who will then help determine what course of action should be taken in dealing with the remains. Per Public Resources Code 5097.98, the landowner shall ensure that the immediate vicinity, according to generally accepted cultural or archaeological standards or practices, where the Native American human remains are located, is not damaged or disturbed by further
Page 66 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 development activity until the landowner has discussed and conferred, as prescribed in this section (Public Resources Code 5097.98), with the most likely descendants regarding their recommendations, if applicable, taking into account the possibility of multiple human remains.
Page 67 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.6 Geology and Soils
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Expose people or structures to potential substantial adverse
effects, including the risk of loss, injury or death, involving: i) Rupture of a known earthquake fault, as delineated on the most recent Alquist-Priolo Earthquake Fault Zoning Map issued by the State
Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42. ii) Strong seismic ground
shaking? iii) Seismic-related ground failure, including liquefaction? iv) Landslides? b) Result in substantial soil erosion
or the loss of topsoil? c) Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and
potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction or collapse? d) Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code (1994), creating substantial risks to life or property?
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Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated e) Have soils incapable of adequately supporting the use of septic tanks or alternative
wastewater disposal systems where sewers are not available for the disposal of wastewater?
4.6.1 Existing Setting
The geologic setting of the Project site is based on existing reports and maps, including the Sweetwater Community Plan (County of San Diego 2014), U.S. Geological Survey (USGS), California Geological Survey (CGS) maps, and previous geotechnical investigations (e.g., Ninyo and Moore 2005; GEI 2016). The Project site is regionally located in Southern California, which is a seismically active region at the junction of the North American and Pacific tectonic plates. In comparison to other southern California areas, San Diego County has sparse seismicity. However, since 1984, earthquake activity in San Diego County has doubled over that of the preceding 50 years (County of San Diego 2017). There are no known active faults (i.e., faults that exhibit evidence of ground displacement in the last 11,000 years) or potentially active faults (i.e., faults that exhibit evidence of ground displacement in the last 2,000,000 years) in the immediate Project area. The Elsinore Fault has been mapped approximately 38 miles east of the site and the Rose Canyon Fault has been mapped approximately 8 miles west of the site. Ongoing field and laboratory studies suggest the largest credible earthquake predicted for the coastal and metropolitan areas is M7.2 on the Rose Canyon Fault (County of San Diego 2014).
The U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) database was searched to determine which soils are present in the Project site. The database returned four soils within the project area: Diablo Clay, Olivenhain cobbly loam, Riverwash, and San Miguel rocky silt loam (see Figure 3 in Attachment B). These soils are not known to have stability issues, and characteristics are further described in Table 7. Soil liquefaction occurs within relatively loose, cohesion-less sands that are saturated from a relatively high groundwater table (less than 50 feet below ground surface). Seismically induced soil liquefaction is a phenomenon in which loose to medium dense, saturated granular materials undergo matrix rearrangement, develop high pore water pressure, and lose shear strength due to cyclic ground vibrations induced by earthquakes or other means. Because the soils present in the project area are not sandy, no stability issues would be expected.
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Table 7. Soils within the Project Area Map Unit Name Soil Characteristics Well-drained, moderately deep to deep clays derived from soft, Diablo clay, 15 to 30 percent calcareous sandstone and shale. This soil type has a moderate slopes potential for erosion. Well-drained, slow-to-medium runoff and very slow Olivenhain cobbly loam, 9 to permeability soils. This soil type has a moderate potential for 30 percent slopes erosion. Occurs in intermittent stream channels and consists of sandy, Riverwash gravely, or cobbly material. It is excessively drained and rapidly permeable. San Miguel rocky silt loam, 9 Well-drained, shallow to moderately deep silt loams that have to 30 percent slopes clay subsoil. This soil type has a low potential for erosion. Source: USDA 2017.
4.6.2 Discussion a, c, d. No Impact. Extensive geotechnical investigations have been completed in support of the construction of and modifications to the Sweetwater Dam and the associated north and south spillways. Additionally, investigations have also been completed in support of activities adjacent to the dam (e.g., Robert A. Perdue Water Treatment Plant Master Plan for Future Plant Activities). The area in the immediate vicinity of the dam is underlain by very hard metavolcanic rock (i.e., metamorphic rock originally formed from a volcano then buried and subjected to high pressures and temperatures causing the rock to recrystallize) (Ninyo & Moore 2005). No known underlying active faults are located in the Project area (Ninyo & Moore 2005; GEI 2016; County of San Diego 2014). Therefore, no impacts associated with ground surface rupture due to faulting would occur in the vicinity of the Sweetwater Dam or South Spillway. Also, due to the Project site location, elevation, and underlying materials, no impacts associated with liquefaction, seismically induced settlement, lateral spread, and tsunamis would occur with implementation of the improvements to the Sweetwater Dam and South Spillway. No landslides or indications of deep-seated landslide activity are identified in the vicinity of the dam and no impacts associated with landslides are anticipated to occur with improvements to the Sweetwater Dam and South Spillway. The groundwater table in the vicinity is located below the depths of the proposed improvements and no impacts to groundwater are anticipated to occur with implementation of the improvements to the Sweetwater Dam and South Spillway.
A geotechnical exploration program was performed at the South Dike by GEI in December 2014 and January 2015 (GEI 2016). The South Dike embankment fill materials at boring locations consisted of well-compacted clays and clayey sands with high plasticity. The overburden materials above the Mission Valley Formation consisted of clay, sandy clay, and clayey sand with moderate to high plasticity fines. The Mission Valley Formation typically consisted of interlayers of sandstone and claystone (GEI 2016). These materials are not considered susceptible to liquefaction and no landslides are mapped in or adjacent to the area of the South Dike in the reviewed geologic reports (GEI 2016; Tan 1992, 2002; Todd 2004).
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Based on previously conducted geotechnical investigations, the proposed Project would not expose people or structures to adverse effects involving rupture of a known earthquake fault, strong seismic ground shaking, ground failure, liquefaction or landslides. Therefore, no impacts are anticipated to occur. b. Less than Significant. The proposed Project would not include activities that could result in substantial erosion or the loss of topsoil. As described in Section 1.4, Project Objectives and Scope, a primary objective of the proposed Project is to protect highly erodible areas by confining PMF discharges over dam’s spillways to areas protected by existing concrete walls and slabs and ultimately into the existing stilling basin at the base of the dam. The proposed Project has been designed and engineered to accomplish this objective (refer to Section 1.5, Project Elements).
The improvements to the South Dike would require earthen fill to be taken from an existing soil stockpile that is located approximately 200 feet to the southwest of the South Dike. The soil stockpile has been used for over 25 years as a disposal site for soils from trenching projects performed by the Authority. The material in the soil stockpile area is generally suitable for use as fill for construction of the new embankment portion of the dike raise. However, the material will require some processing to remove oversized material, organic material, and debris (GEI 2016).
The improvements to the South Abutment Access Road would require grading to widen the road and create a 50-foot wide turnout/staging near the south end of the dam. These improvements would result in the removal of topsoil, however, as described in Section 4.9, Hydrology and Water Quality, standard BMPs and Several segments of dirt roads will be grading techniques would ensure that erosion would be improved to support construction minimized. BMPs would include soil pile coverage, activities associated with the proposed sediment controls, reduced vehicle speeds on unpaved Project. The soils in the Project area roads. These BMPs would be memorialized in a currently support existing infrastructure SWPPP, which shall describe all of the procedures and no known geologic risks exist within the Project site. necessary to meet the erosion protection and sediment control requirements of all applicable laws and regulations, and required Project permits (refer to Section 1.7, Project Construction). Additionally, where substantial grading would occur to support the 50-foot wide turnout/staging area, limited excavation and fill would be required. Additionally, temporary retaining structures would be installed, as necessary, to contain the fill slope (e.g., gabion baskets, welded wires, or bag wall) (refer to Section 1.5.5, South Abutment Access Road Improvements).
Overall, it is anticipated that impacts to substantial erosion or the loss of topsoil as a result of the proposed Project would be less than significant.
Page 71 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 e. No Impact. The proposed Project would not require the use of septic tanks or wastewater disposal systems. Therefore, no impacts to septic systems or alternative wastewater treatment systems would occur as a result of the proposed Project.
Page 72 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.7 Greenhouse Gas Emissions
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Generate greenhouse gas emissions, either directly or indirectly, that may have a significant impact on the environment? b) Conflict with an applicable plan, policy or regulation adopted for
the purpose of reducing the emissions of greenhouse gases?
4.7.1 Existing Setting
Global climate change can be measured by changes in wind patterns, storms, precipitation, and temperature. Scientific consensus has identified human-related emissions of greenhouse gases (GHGs) above natural levels is a significant contributor to global climate change. GHGs are emissions that trap heat in the atmosphere and regulate the Earth’s temperature, and include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), ground level ozone, and fluorinated gases, such as chlorofluorocarbons (CFCs), hydro chlorofluorocarbons (HCFCs), and halons. The potential impacts of climate change include severe weather patterns, flooding, reduced quality and availability of water, sea level rise, and beach erosion. Primary activities associated with GHG emissions include transportation, operation of utilities (e.g., power generation and transport), industrial activities, manufacturing, agriculture, and residential uses. End-use sector sources of GHG emissions in California are as follows: transportation (37 percent), industry (23 percent), electricity generation (20 percent), agriculture and forestry (8 percent), residential (7 percent), and other (5 percent) (CARB 2016).
Assembly Bill (AB) 32 is a California State Law that establishes a comprehensive program to reduce GHG emissions from all sources throughout the state. AB 32 requires CARB to develop regulations and market mechanisms to reduce California’s GHG emissions to 1990 levels by 2020, representing a 25 percent reduction statewide, with mandatory caps beginning in 2012 for significant emissions sources (CARB 2014).
GHG Emissions Thresholds
As mentioned in Section 4.3, Air Quality, the Project site is located within the SDAPCD. The SDAPCD has not yet approved a threshold of significance for GHG emissions. The significance threshold considered in this document is based on the work of the California Air Pollution Control Officers Association (CAPCOA). CAPCOA investigated a variety of analytical procedures and ranges of what would be considered significant for a project, and suggests a conservative
Page 73 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 screening criteria threshold of 900 metric tons per year of CO2e (MT/yr CO2e) for a development project to be considered potentially significant. CAPCOA notes that a zero threshold would be appropriate for global, cumulative effects from greenhouse gases. Due to the current global situation, any addition of greenhouse gas emissions could be considered significant. Other thresholds that could be used include a 10,000 MT/yr CO2e measurement by the Market Advisory Committee, or the highest considered threshold of 50,000 MT/yr CO2e by CAPCOA for large- scale construction projects. The most conservative threshold option of 900 MT/yr CO2e has been used to evaluate this Project (CAPCOA 2008).
4.7.2 Discussion a, b. Less than Significant. The proposed Project would primarily generate increased GHG emissions over the short-term related to operation of construction equipment. The total emission from Project construction was modeled using CalEEMod estimates for a 2019 operational year (see Attachment A). Emissions from construction would consist of mobile sources such as haul trucks and other construction equipment. The total estimated emissions from construction activity would be 63.90 MT/yr CO2e in 2017, 597.73 MT/yr CO2e in 2018, and 56.22 MT/yr CO2e in 2019, which are well below the conservative CAPCOA significance threshold of 900 MT/yr CO2e.
Project operational activities would emit GHGs from minimal maintenance activities required to upkeep the structures. As discussed in Section 4.3, Air Quality, the Project would generate less than significant impacts to regional and local air quality, and all Project construction would be conducted in compliance with all SDAPCD rules and regulations. Further, GHGs anticipated from the Project would be far below those adopted to date by any air district in the State. Therefore, the Project specific and cumulative impacts related to GHGs would be less than significant.
Table 8. Estimated Construction GHG Emissions (MT CO2e/yr) Construction Year GHG Emissions 2017 63.90 2018 597.73 2019 56.22 Maximum 597.73 CAPCOA Thresholds of Significance 900 Significant? No Source: CalEEMod, Version 2016.3.2. See Attachment A for complete results.
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4.8 Hazards and Hazardous Materials
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Create a significant hazard to the public or the environment through
the routine transport, use or disposal of hazardous materials? b) Create a significant hazard to the public or the environment through reasonably foreseeable upset
and accident conditions involving the release of hazardous materials into the environment? c) Emit hazardous emissions or handle hazardous or acutely hazardous materials, substances
or waste within one-quarter mile of an existing or proposed school? d) Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code §65962.5 and, as a result, would it create a significant hazard to the public or the environment? e) For a project located within an airport land use plan area or, where such a plan has not been adopted, within two miles of a public airport or a public use airport, would the project result in a safety hazard for people residing or working in the project area? f) For a project within the vicinity of a private airstrip, would the project result in a safety hazard for people residing or working in the project area?
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Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated g) Impair implementation of, or physically interfere with, an adopted emergency response plan or emergency evacuation plan? h) Expose people or structures to a significant risk of loss, injury or death involving wildland fires, including where wildlands are adjacent to urbanized areas or where residences are intermixed with wildlands?
4.8.1 Existing Setting
The San Diego County Department of Environmental Health – Hazardous Materials Division is the Certified Unified Program Agency (CUPA) for San Diego County. Government Code Section 65962.5 requires the California Environmental Protection Agency (Cal EPA) to develop and annually update the Hazardous Waste and Substances List – Site Cleanup (Cortese) List. Information on the location of hazardous material sites contained in the Cortese List is provided by the Department of Toxic Substances Control (DTSC). A review of the Cortese List indicates that there are no identified hazardous materials release sites located within the Project area (DTSC 2007). In addition, a review of the DTSC EnviroStor Database did not indicate any cleanup sites or hazardous waste facilities within the vicinity of the Project area (DTSC 2017).
The closest school is Sunnyside Elementary School, which is located approximately 1.6 miles away from the Project area. The nearest public airport, Brown Field Municipal Airport, is located approximately 8.2 miles from the Project area. The proposed Project is not located within an airport land use plan area. The Project area is not located within the vicinity of a private airstrip. Public access is restricted to the Sweetwater Dam and Reservoir area, and there are no through roadways. There is a hiking and riding trail located in the vicinity of the project area, which will be affected by construction activities at the South Dike. Mitigation measures will be implemented to reduce impacts to traffic along the trail. These are discussed further in Section 4.15, Recreation. The California Department of Forestry and Fire Protection (Cal Fire) designates the proposed Project within an area of wild land urban interface and moderate fire hazard severity (County of San Diego 2011c).
4.8.2 Discussion a. Less than Significant. During Project construction activities, typical hazardous materials would be used at the site, including hydraulic fluids and vehicle fuels for construction equipment. Additionally, materials delivery and concrete trucks supporting the construction activities at
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Sweetwater Dam would access the Project site either via Sweetwater Reservoir Road or Conduit Road, which passes adjacent to the east side of the Bonita Golf Course and near residents. Materials delivery trucks and other heavy construction equipment supporting the South Dike and South Spillway would access the site via Summit Meadow Road, which also passes near residents. The construction phase may include the transport and on-site storage of petroleum products for the purpose of fueling construction equipment. However, the use and transport of these materials during construction activities would be short-term in nature and would occur in accordance with standard construction BMPs. All transport, handling, use, and disposal of substances such as petroleum products related to Project construction would comply with applicable federal, state, and local health and safety regulations. Although Project construction would involve short-term activities involving transport of hazardous materials; however, long-term Project maintenance activities (e.g., culvert or road maintenance) would not create a substantial hazard to the public or environment through the routine transport, use, or disposal of hazardous materials. Therefore, impacts associated with the proposed Project would be less than significant. b. Less than Significant. The proposed Project may result in a potential risk of upset or accidental release of hydraulic fluid or vehicle fuel resulting from construction activities within the Project area or along construction haul routes. However, all transport, handling, use, and disposal of substances such as petroleum products related to Project construction activities would comply with all federal, state, and local laws regulating the management and use of hazardous materials. Additionally, standard construction BMPs (e.g., fueling off-site, clearing of dried vegetation from all areas slated for development using spark-producing equipment, and development and implementation of a Spill Prevention Plan) would be in place for the duration of Project construction to ensure the proper use and storage of these materials so that reasonably foreseeable risks of upset involving the release of hazardous materials into the environment are avoided and minimized. There would be minimal potential for the release of hazardous materials into the environment during long-term Project operations. Therefore, impacts are anticipated to be less than significant. c. No Impact. The proposed Project would not emit hazardous emissions or handle hazardous materials, substances or waste within 0.25-mile of an existing or proposed school. The closest school is Sunnyside Elementary School, which is located approximately 1.6 miles away from the Project area. Therefore, no impacts are anticipated to occur as a result of the implementation of the proposed Project. d. No Impact. Pursuant to Government Code 65962.5, environmental regulatory database lists were reviewed to identify and locate properties with known hazardous substance contamination within the proposed Project area. The Project is not located on a list associated with hazardous materials and thus would not occur on a hazardous materials site that would create a risk to the public or the environment. Therefore, no impacts are anticipated to occur as a result of the implementation of the proposed Project. e, f. No Impact. The proposed Project would not create a safety hazard associated with airport operations for people residing or working in the Project area because no airports or private airstrips are located within two miles of the proposed Project area. The nearest public airport, Brown Field Municipal Airport, is located approximately 8.2 miles from the Project area. Therefore, no impacts would occur as a result of the implementation of the proposed Project.
Page 77 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 g. No Impact. The County maintains a comprehensive Flood Warning System that assesses flood risk and provides advance warning of impending flooding (County of San Diego 2007). The Flood Warning System consists of real-time rainfall and stream flow gages located throughout San Diego County and a base station located at the County Department of Public Works office that collects and processes the incoming data. The County Department of Public Works assists in the dissemination of general information, maps of potential inundation areas, and proposed evacuation routes information to the public. Further, during flood events, the County Department of Public Works staff serves as an emergency responses team and performs a variety of emergency tasks such as answering phone calls, storm monitoring, radio dispatching, field patrolling, and computer modeling for flood flow forecasting. Emergency operations also include pre-planned routines such as the monitoring of all flood facilities and equipment and the provision of logistics support, field operations headquarters, and responses to emergency situations (County of San Diego 2007). The proposed Project would not result in changes that would interfere with emergency response or evacuation plans related to flooding or any other natural hazards. Public access to the Project area is restricted and there are no through roadways, thus the Project would not impair any public roadway that could potentially interfere with emergency response. The proposed Project would not impair or physically interfere with an adopted emergency response plan or a local, state, or federal agency’s emergency evacuation plan. Therefore, no impacts are anticipated to occur as a result of the implementation of the proposed Project. h. Less than Significant. Wildland fires represent a significant threat in the State and in San Diego County, particularly during the hot, dry summer months in more isolated areas where steep topography, limited access, and heavy fuel loading contribute to hazardous conditions. Wildland fire may be started by natural processes, primarily lightning, or it may be started by human activities. Fire risk is dependent upon the moisture level in the plants and the presence of incendiary sources. Fire risk is significant if it places residents or the public in a situation of endangerment because of inadequate services, resources, and/or safety measures, creates or exacerbates an existing fire hazard, or exposes people to high fire hazard conditions without adequate fire protection. Lastly, a fire risk is significant if it impairs response times.
The entire Project area is located outside of the Fire Hazard Severity Zones for both State Responsibility Areas and Local Responsibility Areas (Cal Fire 2007). The proposed Project would not add structures that could be exposed to fire risk. In addition, the proposed Project would not include development of any habitable structure which could place an individual in a situation of endangerment. No features of the proposed Project would change the fire hazard severity zones and long-term Project operations would not impact response times of local fire departments. Construction and extension of the South Abutment Access Road would be beneficial to emergency access to the south side of the dam by improving the unpaved road and extending the road to allow for large vehicle access such as for a fire engine. The proposed Project would have no impacts related to exposing people or structures to a significant risk of loss, injury or death involving wildland fires. Therefore, no impacts are anticipated to occur. Construction of the proposed Project would require equipment and activities that use petroleum fuels and oil and could result in accidental spills and sparks leading to fire-related hazards. Implementation of construction BMPs, including clearing of dry vegetation prior to use of spark-producing equipment and proper use of spark arrestors (refer to Section 1.6, Project Design Considerations), would reduce impacts due to wildland fires to less than significant levels.
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4.9 Hydrology and Water Quality
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Violate any water quality standards or waste discharge requirements? b) Substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of pre-existing nearby wells would drop to a level which would not support existing land uses or planned uses for which permits have been granted)? c) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a
stream or river, in a manner which would result in substantial erosion or siltation on- or off- site? d) Substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner that would result in flooding on- or off-site?
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Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated e) Create or contribute runoff water which would exceed the capacity of existing or planned storm
water drainage systems or provide substantial additional sources of polluted runoff? f) Otherwise substantially degrade
water quality? g) Place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard
Boundary or Flood Insurance Rate Map or other flood hazard delineation map? h) Place within a 100-year flood hazard area structures that
would impede or redirect flood flows? i) Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of a failure of a levee or dam? j) Expose people or structures to a significant risk of loss, injury or
death involving inundation by seiche, tsunami or mudflow?
4.9.1 Existing Setting
San Diego Region is defined as Region 9 by the RWQCB, and include approximately 3,900 square miles of surface area. The San Diego Region has 13 principal stream systems originating in the western highlands which flow to the Pacific Ocean. The region is divided into 11 major hydrologic units (HUs), 54 hydrologic areas (HAs), and 147 hydrologic subareas (HSAs). HUs are the entire watershed of one or more streams; HAs are major tributaries and/or major groundwater basins within the HU; and HSAs are major subdivisions of HAs including both water-bearing and nonwater-bearing formations. The RWQCB has designated Sweetwater Reservoir and its surrounding areas as being in the Sweetwater HU (Basin 9.00). This HU is a 230-square mile elongated strip that is traversed along its length by the Sweetwater River stretching from the eastern boundary of RWQCB Region 9 in the Laguna Mountains to San Diego Bay. The watershed has four major water bodies, the Sweetwater River, Sweetwater Reservoir, Loveland Reservoir, and San Diego Bay. The Sweetwater HU includes separate and fully functional HAs: Page 80 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Lower Sweetwater (9.10), Middle Sweetwater (9.20), and Upper Sweetwater (9.30) (RWQCB 2016). The Lower Sweetwater River is included on the 303(d) List of Impaired Waters for Enterococcus, Fecal Coliform, Phosphorus, Selenium, Total Dissolved Solids, Total Nitrogen as N and toxicity (State Water Resources Control Board [SWRCB] 2016). Additionally, the Sweetwater Reservoir is listed on the 303(d) List of Impaired Waters for dissolved oxygen (SWRCB 2016).
Sweetwater Reservoir is a drinking water reservoir that receives water from the Sweetwater River watershed, as well as imported water from the San Diego County Water Authority, with the quality affected by upstream watershed development and activities. Surface and ground waters flowing into Sweetwater Reservoir are treated at the Robert A. Perdue Water Treatment Plant prior to delivery to its customers. The Authority also supplements its local water supply with treated water purchased from the San Diego County Water Authority.
The Sweetwater Reservoir Urban Runoff Diversion System (URDS) is located along the north side of the reservoir. The main purpose of the URDS is to minimize stormwater pollution in the reservoir resulting from upstream residential developments and industrial areas. Minimization of stormwater pollution is achieved mainly by capturing polluted runoff from the “first flush” and dry– season low flows. The system can also capture hazardous spills, preventing water pollution in the reservoir.
Regulations
Improvements such as the proposed Project could affect the water quality of the Sweetwater Reservoir through sedimentation, runoff of hazardous substances, and/or waste. Section 402 of the federal Clean Water Act established the National Pollutant Discharge Elimination System (NPDES) to regulate discharges into navigable “waters of the U.S.” The SWRCB issues NPDES permits in the State of California, including the NPDES permit that ensures that construction sites are in compliance with the Clean Water Act. Construction projects disturbing one or more acres of soil are required to file for coverage under SWRCB Order No. 2009–0009–DWQ, NPDES General Permit No. CAS000002 for Discharges of Storm Water Runoff Associated with Construction Activity (Statewide Construction General Permit; CGP). To comply with the permit the Authority or its Contractor must file a complete and accurate Notice of Intent (NOI) with the SWRCB prior to construction. Compliance requires conformance with applicable BMPs and the preparation and implementation of a SWPPP and monitoring program. The SWPPP is a working document that is updated and modified throughout construction to detail any changes in implementation of BMPs, any noncompliance, and resolution thereof. Upon completion of construction, the permit holder must file a Notice of Termination with the SWRCB. The SWPPP must be retained on-site for 3 years after acceptance of the Notice of Termination.
In addition to NPDES requirements, other laws and regulations may apply, including but not limited to, compliance with sections 404 and 401 of the Clean Water Act. Any impacts to jurisdictional wetlands and waters of the U.S. and State are addressed Section 4.4, Biological Resources.
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4.9.2 Discussion a, f. Less than Significant. As described in Section 1.5, Project Elements, the improvements under the proposed Project include raising the parapet walls on the north and south ends of Sweetwater Dam, restoration of the South Spillway, and the expansion of the South Dike. Staging areas would be required in several locations during construction (refer to Figure 2). These construction activities, including excavation, grading, or vegetation removal, which would result in land disturbance of one or more acres, are subject to the Statewide CGP. The CGP requires the preparation and implementation of a SWPPP to prevent and minimize impacts from construction activities to waters of the U.S. and State to the maximum extent possible. Prior to commencement of construction, the contractor would submit a NOI to the SWRCB and begin preparation of a SWPPP. The SWPPP would be implemented during all phases of the project and retained on- site. The SWPPP would be updated as necessary and in compliance with the Statewide CGP. Short-term erosion effects during the construction phase of the project would be prevented through the required implementation of a program of BMPs and best available technologies to reduce impacts to water quality that may result from construction activities. BMPs would be selected to achieve maximum sediment and erosion control and represent the best available technology that is economically achievable. Compliance with the terms and conditions of the Statewide CGP and implementation of the SWPPP would reduce impacts to less than significant levels.
Once the construction activities are completed, maintenance activities would be conducted, as necessary, to ensure compliance with DSOD regulations. The proposed Project incorporates standard BMPs for future maintenance activities to prevent erosion and sediment transport. Implementation of standard BMPs during maintenance activities would prevent erosion and sedimentation that could impact water quality.
Standard BMPs for future maintenance activities include, but are not limited, to the following:
a. Vehicle and equipment cleaning before construction activities; b. Delineation of Limits of Disturbance; c. Preservation of existing vegetation, to the greatest extent feasible; d. Installation of silt fencing and sediment barriers as appropriate, to minimize sedimentation in receiving waters; e. Application of soil binders, if needed; f. Covering soil piles with plastic to ensure dust control; g. Placement of flow barriers around temporary equipment storage areas located within primary staging area to prevent storm water flow from entering or leaving the project area; h. If pollutants or sediments from the maintenance site enter the rivers, creeks, or drainage swales, the pollutants and sediments shall be removed immediately; i. Creation of earth dikes/drainage swales and lined ditches to improve drainage; j. Designate fueling areas at least 50 feet away from any receiving waters; k. BMPs for construction materials use, storage, and disposal; l. Spill prevention control measures at site; and m. Other BMPs as recommended by qualified individuals
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BMPs will be memorialized in the SWPPP prepared for the proposed Project. The proposed Project and future maintenance activities are not expected to degrade water quality and impacts to the Sweetwater Reservoir or adjacent streams are anticipated to be less than significant. b. No Impact. The proposed Project would not use groundwater for any purpose. Thus, the proposed Project would not substantially deplete groundwater supplies or interfere substantially with groundwater recharge such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level. Therefore, no impacts are anticipated to occur. c, e. Less than Significant. The proposed Project would neither alter existing drainage patterns nor the course of any stream or river that would result in flooding on- or off-site. The proposed Project would not involve any physical changes to the environment that would contribute or create runoff water that would exceed the capacity of existing drainage systems or provide a substantial source of polluted runoff. Additionally, as described above, a SWPPP, which includes the necessary construction BMPs and monitoring would be implemented to further reduce the possibility of polluted runoff or sediment deposition. Therefore, impacts to water quality from erosion or runoff are anticipated to be less than significant. g, h. Less than Significant. The proposed Project would not place any housing or new structures within the 100-year floodplain, as the entire Project site is located in Flood Zone X (Federal Emergency Management Agency [FEMA] 2012). As described in Section 1.4, Project Objectives and Scope the proposed Project was designed to minimize flood risk by allowing Sweetwater Dam to pass the PMF. As such, implementation of the Project would reduce flood risk for all residents down stream of Sweetwater Dam. The proposed Project does not involve the construction of any new structures, but will improve upon existing structures, in order to accommodate the PMF. Implementation of the proposed Project would reduce the potential for flooding and associated hazards downstream of the dam. Therefore, less than significant impacts are anticipated to occur with implementation of the proposed Project. i. Less than Significant. The proposed Project is expected to reduce the risk of damage to structures as a result of flood patterns. As described above, and in Section 1.4, Project Objectives and Scope, the purpose of the Project is to improve the Sweetwater Dam and the South Dike to safely pass and contain storm water flows associated with a PMF, thereby reducing the exposure of people and structures to impacts associated with flooding. Implementation of the proposed Project may minimally alter flood patterns, by restoring them to the drainage channel that was initially intended for Sweetwater Dam. Therefore, impacts would be beneficial and less than significant. j. Less than Significant. The Project would not increase the risk associated with seiche, tsunami, or mudflow beyond those of the existing conditions. Implementation of the proposed Project would reduce risks associated with seiche, tsunami or mudflow by reinforcing existing structures and improving Sweetwater Dam and the South Dike to accommodate the PMF. Therefore, impacts would be beneficial and less than significant.
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4.10 Land Use and Planning
Less Than Potentially Significant Less Than Significant with Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Physically divide an established
community? b) Conflict with any applicable land use plan, policy or regulation of an agency with jurisdiction over the project (including, but not limited to, the general plan,
specific plan, local coastal program or zoning ordinance) adopted for the purpose of avoiding or mitigating an environmental effect? c) Conflict with any applicable habitat conservation plan or
natural community conservation plan?
4.10.1 Existing Setting
The Project area is located in unincorporated San Diego County; there are no established communities located on Authority property in the Project area. The Project area is designated Public Agency Lands and is zoned S80 – Special Purpose (County of San Diego 2014; County of San Diego Planning and Development Services 2012). The Authority is the principal agency that has jurisdiction over the Project area and provides water service to customers in the Project vicinity. DSOD also has jurisdiction over Sweetwater Dam. The proposed Project is not located within an approved habitat conservation plan area or a natural community conservation plan area.
4.10.2 Discussion a – c. No Impact. The proposed Project is located in a rural unincorporated area of the County and would not involve changes in land use nor would it involve construction near any established communities. The Project does not propose any action that could divide an established community. The proposed Project would not involve any land use changes or actions that would conflict with applicable land use plans, policies, or regulations in the proposed Project area. The proposed Project would be consistent with the County’s existing zoning of the Project area, Special Purpose (S80), and would be exempt under California Government Code sections 53091(d) and (e) from the County of San Diego’s building and zoning ordinances, which do not apply to the location or construction of facilities for the production, generation, storage, treatment, or transmission of water by a local agency. The proposed Project would allow Sweetwater Dam
Page 84 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 to comply with DSOD regulations to have the capacity to safely pass the PMF. The proposed Project would not conflict with the MSCP or any other applicable HCP or NCCP (refer to Section 4.4, Biological Resources). Therefore, no impacts would occur as a result of the implementation of the proposed Project.
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4.11 Mineral Resources
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Result in the loss of availability of a known mineral resource that
would be of value to the region and the residents of the state? b) Result in the loss of availability of a locally important mineral resource recovery site
delineated on a local general plan, specific plan or other land use plan?
4.11.1 Existing Setting
The California Department of Conservation (DOC) classifies the regional significance of mineral resources in accordance with the California Surface Mining and Reclamation Act of 1975 (SMARA). DOC designates Mineral Resources Zones (MRZs) that have regionally significant mineral deposits. The Sweetwater River deposited Quaternary-age alluvium and slopewash (Kennedy and Tan 1977). The proposed Project would not cause a loss of availability of a locally- important mineral resource recovery site delineated on a local general plan. These alluvial deposits are interbedded with slopewash, which are poorly consolidated materials deposited along the flanks of the lower valley slopes by the interaction of gravity and water (ESA 2013). There are several mineral resource areas associated with Sweetwater River and Reservoir, however they are located to the east and west of the Project site.
4.11.2 Discussion a, b. No Impact. No mineral resources have been identified within the proposed Project area. As a result, the proposed Project would not result in the loss of availability of a locally important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan. Though there are aggregate alluvial deposits to the east and to the west of Sweetwater Reservoir, the Project site is not located within an area with mineral resources (California Department of Conservation 2015). Additionally, the proposed Project will be implemented within previously developed areas, and would not reduce access to nor availability of mineral resources. Therefore, no impacts to mineral resources would occur as a result of the implementation of the proposed Project.
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4.12 Noise
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project result in: a) Exposure of persons to or generation of noise levels in excess of standards established
in the local general plan or noise ordinance or of applicable standards of other agencies? b) Exposure of persons to or generation of excessive
groundborne vibration or groundborne noise levels? c) A substantial permanent increase in ambient noise levels in the project vicinity above levels existing without the project? d) A substantial temporary or periodic increase in ambient noise levels in the project vicinity above levels existing without the project? e) For a project located within an airport land use plan area or, where such a plan has not been adopted, within two miles of a public airport or a public use airport, would the project expose people residing or working in the project area to excessive noise levels? f) For a project within the vicinity of a private airstrip, would the project expose people residing or working in the project area to excessive noise levels?
4.12.1 Existing Setting
The San Diego County Noise Ordinance (San Diego County Code Section 36, Chapter 4) and the County’s General Plan both establish noise standards for the County. The County’s noise Page 87 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 regulations range from 45 A-weighted decibels (dBA) to 75 dBA, depending on the land use zoning and time of day (see Table 9).
Table 9. San Diego County Noise Standards Zoning Noise Level (dBA) Time Period Residential 45 10 PM to 7 AM Residential 50 7 AM to 10 PM Commercial 55 10 PM to 7 AM Commercial 60 7 AM to 10 PM Industrial 75 Any time Source: County of San Diego (2008)
Noise pollution in certain areas of the Sweetwater CPA already exceeds the County's published noise standards (County of San Diego 2014). The greatest noise pollution exists along Interstate (I-) 805 with the Community Noise Equivalent Level (CNEL) reaching 79 decibels (dB). The Project area is characterized by largely undeveloped open space and the noise environment surrounding the Project area is influenced primarily by distant truck and automobile traffic. Within the Project vicinity, the greatest noise pollution occurs at SR-125, which produces levels between 73 and 76 dB, and along Bonita Road and Sweetwater Road. Bonita Road varies from 75 dB at the I-805 ramp to 60 dB at San Miguel Road. Sweetwater Road produces CNEL of 73 decibels at the I-805 ramp to 64 decibels in the vicinity of Quarry Road (County of San Diego 2014). Construction access to the Project site may include haul routes along Quarry Road, which is located in a residential area, and Conduit Road, which is located adjacent to the Bonita Golf Course and in a residential area. The proposed Project is not located within an airport land use plan area and is not located within two miles of a public airport or within vicinity of a private airstrip.
4.12.2 Discussion a. Less than Significant with Mitigation Incorporated. The Project would result in a temporary increase in noise levels due to short-term daytime construction activities and intermittent heavy construction equipment use over the three construction phases described in Section 1.7, Project Construction. Noise from Project activities would include excavation, grading, demolition, drilling and grouting concrete, and other construction activities that would temporarily increase ambient noise levels in the Project area. Typical noise levels from construction equipment are shown in Table 10. Construction-related activities within the immediate vicinity of the dam, South Spillway, South Dike, and South Abutment Access Road would temporarily increase ambient noise levels in these areas. While the proposed construction areas at the dam and along the South Abutment Access Road are located over 1,000 feet from the nearest residents, construction noise in the vicinity of the South Dike could have short-term impacts on trail users in this area. Additionally, material haul trips would temporarily raise ambient noise levels along haul routes within residential areas and adjacent to the Bonita Golf Course over the 12- to 16-month construction period. However, construction noise would be intermittent and temporary and following construction long- term operational noise would not change from current site conditions. With incorporation of MM NOI-1, Project-related construction noise would be less than significant with mitigation incorporated.
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Table 10. Typical Construction Noise Levels Construction Equipment Noise Level (dBA, Leq)* Ground Clearing 84 Excavation 89 Foundation 78 Erection 85 Finishing 89 Notes: * Average noise levels correspond to a distance of 50 feet from the noisiest piece of equipment associated with a given phase of construction and 200 feet from the rest of the equipment associated with that phase. Source: USEPA 1971
Table 11. Typical Noise Levels from Construction Equipment Construction Equipment Noise Level (dBA, Leq at 50 feet) Dump Truck 88 Portable Air Compressor 81 Concrete Mixer (Truck) 85 Scraper 88 Jack Hammer 88 Dozer 87 Paver 89 Generator 76 Rock Drill 98 Backhoe 85 Source: Cunniff 1977
Noise Mitigation Measures for (a)
NOI-1. To mitigate the noise impact associated with construction noise, the Authority shall ensure that:
• All construction equipment, fixed or mobile, shall be equipped with properly operating and maintained mufflers. • Construction noise reduction methods such as shutting off idling equipment, installing temporary acoustic barriers around stationary construction noise sources, and use of electric air compressors and similar power tools, rather than diesel equipment, shall be used where feasible. Unattended construction vehicles shall not idle for more than 5 minutes when located within 200 feet from residential properties. • During construction, stationary construction equipment shall be placed such that emitted noise is directed away from or shielded from the residences located within 200 feet. • During construction, stockpiling and vehicle staging areas shall be located as far as practical from noise-sensitive receptors. • Construction hours, allowable workdays, and the phone number of the job superintendent shall be clearly posted at all construction entrances to allow surrounding property owners and residents to contact the job superintendent if necessary. In the event that the Authority Page 89 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
receives a complaint, appropriate corrective actions shall be implemented and a report of the action provided to the reporting party. b. Less than Significant. No permanent increase in groundborne vibration or groundborne noise levels would result from the proposed Project. The Project would involve intermittent use of heavy equipment for short-term construction activities, which has potential to cause a temporary increase in groundborne vibration. However, no blasting or pile driving would be used during Project construction and vibrational noise from construction equipment would be minimal. There are no operational or maintenance activities that would include vibration and the short duration of Project construction activities would not generate a significant amount of groundborne vibration. Therefore, the Project would have a less than significant impact. c. No Impact. The proposed Project would be limited to temporary construction and maintenance activities, which would not introduce any permanent sources of noise or result in a permanent increase in ambient noise levels in the Project vicinity. Dam operations and maintenance activities would be similar to those of the existing operations and maintenance activities. Therefore, no impacts are anticipated to occur. d. Less than Significant with Mitigation Incorporated. As previously stated, the proposed Project includes excavation, grading, demolition, drilling, grouting, construction-related material haul trips, and other construction activities that would result in an increase in ambient noise levels above existing levels in the Project vicinity and along haul routes within residential areas and adjacent to the Bonita Golf Course. However, construction activities would generally occur during the daytime hours on weekdays and construction-related noise impacts would be temporary. Ambient noise in the Project vicinity would return to existing levels after Project construction activities are complete. In order to reduce Project-specific noise levels, MM NOI-1 would be incorporated. It is anticipated that impacts associated with creating a temporary increase in ambient noise levels would be less than significant with mitigation incorporated. e, f. No Impact. The proposed Project would not impact any airstrip or airport operations. The Project area consists of largely undeveloped open space and there are no people working or residing in the Project area that would potentially be exposed to excessive noise levels. Therefore, no impacts are anticipated to occur.
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4.13 Population and Housing
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Induce substantial population growth in an area, either directly (e.g., by proposing new homes
and businesses) or indirectly (e.g., through extension of roads or other infrastructure)? b) Displace substantial numbers of existing housing, necessitating
the construction of replacement housing elsewhere? c) Displace substantial numbers of people, necessitating the
construction of replacement housing elsewhere?
4.13.1 Existing Setting
The Project is located within the Sweetwater CPA, an unincorporated portion of San Diego County south of SR-54, east of I-805, north of the City of Chula Vista and west of the Jamul/Dulzura Subregion (County of San Diego 2014). In 2010, SANDAG estimated a population of 13,805 and 4,523 housing units in the Sweetwater CPA (County of San Diego 2014). There are no large scale planned housing or commercial developments within the immediate area. The roads near the Project site are used for thoroughfare travel and access to residential neighborhoods and some commercial businesses. The Project site is not zoned for residential use, and there are no existing residential structures within the Project site.
4.13.2 Discussion a – c. No Impact. The Sweetwater Reservoir is a water supplier to local residents and the existing community, and is operated by the Authority. The proposed Project would not result in any change to the existing land use pattern or trigger substantial growth in the area. The Project includes improvements to existing structures in order to maintain the storage capacity of Sweetwater Reservoir and contain the PMF. Implementation of the proposed Project would not result in the creation of a long-term or permanent water supply that would allow construction of new homes or businesses or extending roadways or other infrastructure that could increase the population in the vicinity of the proposed Project. Further, implementation of the proposed Project would not displace existing housing or necessitate construction of replacement housing elsewhere. Lastly, the proposed Project would not displace people or necessitate the construction of replacement housing elsewhere. Therefore, no impacts are expected to occur. Page 91 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
4.14 Public Services
Less Than Potentially Significant Less Than Significant with Significant No Impact Impact Mitigation Impact Incorporated The Project would be considered to have significant impacts if the Project would result in substantial adverse physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the public services. Would the Project: a) Fire protection? b) Police protection? c) Schools? d) Parks? e) Other public facilities?
4.14.1 Existing Setting
Fire protection within most of the Sweetwater CPA is provided by the Bonita-Sunnyside Fire Protection District (FPD). The District has two permanent fire stations and an approved tentative map for Bonita Meadow Estates includes a condition requiring dedication of a fire station off Proctor Valley Road. The District’s average response time is 2 to 4 minutes, while the longest time is 5 to 6 minutes (County of San Diego 2014). The California Department of Forestry (CDF) also provides wildland brush protection to the southeastern portion of the District and its sphere of influence area. The closest CDF station is located at 2249 Jamacha Road. CDF is part of the County’s Master Mutual Aid agreement, enabling them to respond to fires outside their area of responsibility when needed (County of San Diego 2014). The majority of the Sweetwater CPA – including the entirety of the project area – is not located within a fire hazard severity zone. The Sweetwater CPA, along with the Project site, is located in an area of Unincorporated Local Responsibility Area (LRA) (Cal Fire 2007).
The San Diego County Sheriff’s department provides police protection to the Sweetwater CPA out of its Imperial Beach facility, located at 845 Imperial Beach Boulevard approximately 10 miles southwest of the Project site. Secondary support is provided by the County Sheriff’s Lemon Grove division. Response time in Sweetwater ranges from 10 minutes for priority calls to 15 minutes for non-priority calls. Currently there are no plans for additional stations in the area. Improved service will result from increases in personnel and additional equipment when financial constraints are resolved (County of San Diego 2014).
The Sweetwater CPA is served primarily by three school districts: Chula Vista City Elementary School District, Sweetwater Union High School District, and Southwestern Community College District. The northeast corner of Sweetwater CPA is served by Cajon Valley Union School District. The nearest public schools are Sunnyside Elementary School, Freese Elementary and La Presa Elementary School.
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4.14.2 Discussion a – d. No Impact. The proposed Project would not generate new residents and it would not include construction of any structures that would require additional fire protection services. The proposed Project would not require changes in law enforcement services and it would not include any new housing, businesses, or other development that would increase the demand for police protection services and facilities. The proposed Project would not provide any new housing or employment opportunities that would generate new students or residents in the community and would not increase the demand for school services and facilities or new or expanded park facilities. No other public facilities would be impacted by the proposed Project. Therefore, no impacts are anticipated to occur. e. Less than Significant. The proposed Project would not adversely impact other public facilities since the proposed construction activities would improve existing facilities within Authority property. The Sweetwater Riding and Hiking Trail on the southern boundary of the Project area would be temporarily affected during construction, but trail use would be restored following the completion of construction. Similarly, access to the Sweetwater Reservoir Fishing Program would be limited during the duration of the proposed Project, but it is expected that portions of the Program would remain open for recreational fishing and other visitors. Additionally, implementation of the proposed Project would not include any housing, businesses, or other development that would increase the demand for recreational facilities in the area. Therefore, impacts would be short-term and less than significant, and no mitigation measures would be required.
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4.15 Recreation
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Increase the use of existing neighborhood and regional parks or other recreational facilities
such that substantial physical deterioration of the facility would occur or be accelerated? b) Include recreational facilities, or require the construction or expansion of recreational
facilities, which might have an adverse physical effect on the environment? c) Substantially conflict with the area’s established recreational uses?
4.15.1 Existing Setting
Sweetwater Summit Regional Park is located approximately 500 feet away from the South Dike and 1,000 feet away from the dam. Additionally, a trail network that runs through portions of the Project area along Conduit Road and adjacent to the southern edge of the South Dike. The popular Sweetwater Reservoir Riding and Hiking Trail network consists of approximately 5 miles of trail used primarily for hiking, mountain biking, and horseback riding (refer to Figure 2). The Sweetwater Authority Shoreline Fishing Facility is located along a 2.5-mile stretch on the south side of Sweetwater Reservoir (Authority 2017a). Bonita Golf Course is approximately 2,000 feet away from the Project area. There are no other neighborhood parks, regional parks, or other recreational facilities in the Project vicinity.
4.15.2 Discussion a. No Impact. Implementing the proposed Project would not cause physical deterioration of existing recreational facilities. The proposed Project would not increase the population by introducing new housing or employment opportunities, and thus it would not contribute to increased use of existing regional or local parks, or other recreational facilities, causing their deterioration. Therefore, no impacts are anticipated to occur. b, c. Less than Significant with Mitigation Incorporated. The proposed Project includes realignment of an existing 0.25-mile segment of trail along the southern edge of the South Dike; the 12- to 16-foot wide gravel trail would be realigned further to the south of the South Dike (refer
Page 94 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 to Figure 7). The Project also includes construction of a new trail segment, parallel to SR-125, to connect the existing segment across the incised drainage of the South Dike with the remainder of the Sweetwater Riding and Hiking Trail system. Construction may marginally interfere with access to the Sweetwater Reservoir Fishing Facility. A minor realignment to the Sweetwater Reservoir Fishing Program access road would be necessary for the expansion of the South Dike; however, the fishing area to the east of the South Dike would be expected to remain open and accessible during construction. Improvements to the South Dike would occur over approximately 90 days, the approximate amount of time that the proposed Project would temporarily conflict with the South Dike area’s established recreational trails and Fishing Program.
Construction of the entire Project would take Construction activities in near the approximately 12 to 16 months, where there may be South Dike would have the potential to interrupt existing trail use in this area. minor disruptions of the trail system along Conduit Road The Sweetwater Riding and Hiking for haul trucks to go in and out of the Project area. Trail system is population amongst However, appropriate safety precautions would be taken hikers, mountain bikers, and to ensure there are minimal disruptions of trail use during equestrians. Project construction. Project-related impacts to existing recreational trails would be short-term and would cease once construction is completed. Recreational uses in the Project area would reflect similar conditions after Project construction activities are complete. Minor trail realignments would not have an adverse physical effect on the environment and recreational trails in the Project area would be generally consistent with existing conditions. With implementation of the MM REC-1 and REC-2, as outlined below, the proposed Project would have a less than significant impact.
Recreation Mitigation Measures for (b, c).
REC-1. In order to ensure public safety and access, as feasible, during construction activities the Authority shall:
• Install construction fencing and signs to keep pedestrians out of all active construction area; • Establish and maintain temporary trail detour during construction activities until the proposed trail realignment is open and accessible; • Use a flagman at the South Dike to control construction traffic and ensure avoidance of conflicts with all trail users; • Restrict construction vehicle speeds to 10 miles per hour when driving on the trail north of Conduit Road; • Require that construction vehicles shall come to a complete stop when trail users are encountered; and
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• The Fishing Program is open on Saturdays, Sundays, and Mondays. During construction, ensure access to the Fishing Program to the greatest extent possible.
REC-2. Two weeks prior to construction, public notices shall be posted along Conduit Road and at the South Dike notifying the public of the dates of construction operations and areas of recreation areas closure shall be posted at public access points, restrooms, and other highly visible locations. Signs shall include the construction schedule and overview of any temporary trail detours and/or temporary detours or closure of the Fishing Program access road. Contact information for the public to report immediate construction-related hazards shall also be included on public notices.
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4.16 Transportation/Traffic
Less Than Potentially Significant Less Than Significant with Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Conflict with an applicable plan, ordinance or policy establishing measures of effectiveness for the performance of the circulation system, taking into account all modes of transportation including mass
transit and non-motorized travel and relevant components of the circulation system, including but not limited to intersections, streets, highways and freeways, pedestrian and bicycle paths, and mass transit? b) Conflict with an applicable congestion management program, including, but not limited to level of service standards and travel demand
measures, or other standards established by the county congestion management agency for designated roads or highways? c) Result in a change in air traffic patterns, including either an increase in traffic levels or a change in location that results in substantial safety risks? d) Substantially increase hazards due to a design feature (e.g., sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment)? e) Result in inadequate emergency
access?
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Less Than Potentially Significant Less Than Significant with Significant No Impact Impact Mitigation Impact Incorporated f) Conflict with adopted policies, plans, or programs regarding public transit, bicycle, or
pedestrian facilities, or otherwise decrease the performance or safety of such facilities?
4.16.1 Existing Setting
SANDAG is the designated transportation management agency for the San Diego region under Caltrans. The Metropolitan Transit System (MTS) and the North County Transit District (NCTD) are the two agencies responsible for public transit operations and services in unincorporated areas of the County. Public transit services by these agencies are primarily provided to the larger, more urbanized communities, although limited services are available outside this area. The County’s General Plan Land Use plan and designated road network have a desired level of service (LOS) standard of LOS D; a lower LOS is deemed acceptable only under special circumstances based on specific criteria described in the General Plan (County of San Diego 2011a).
Sweetwater Dam operations and management activities require periodic visits by maintenance personnel to the Dam and South Dike area. Access routes shall be described in a Traffic Plan to be submitted for review by the Authority and for final approval by the County of San Diego County of San Diego prior to construction (refer to Section 1.6, Project Design Considerations). The segment of SR-125 that could serve as a construction haul route to the north end of the dam is a six-lane freeway with a wide landscaped median from the junction of SR-54 to the Jamacha Road overcrossing. This short segment has many traffic transitions taking place at the junction of the SR-54 and the Paradise Valley Road/Jamacha Boulevard interchange. This northbound segment of SR-125 has LOS B and the southbound segment has LOS C; northbound and southbound traffic volumes both peak in the PM (Caltrans 2016). Another potential access route to the south side of the Project could be via the South Bay Expressway and San Miguel Ranch Road. These roadways also operated at an acceptable LOS.
The community of Sweetwater currently provides several Class I and Class II bikeway facilities that total approximately 10.5 miles (Alta Planning & Design 2003). Additionally, there are approximately 5 miles of Class I and Class II bikeway facilities that are proposed for the Sweetwater community area. There are existing and proposed Class II bikeways along proposed Project construction haul routes and Sweetwater Regional Park provides Class I bikeways.
4.16.2 Discussion a, b. Less than Significant. The proposed Project would not adversely affect traffic or transportation patterns over the long-term. Short-term Project construction activities would
Page 98 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 temporarily increase local traffic levels due to the transport and delivery of construction equipment, materials, and daily worker trips. However, the construction equipment and vehicles would be stored on-site within the staging areas. In addition, all parking for construction workers and other required needs during the proposed Project construction would be accommodated on- site in the appropriate staging area, and not on nearby public roadways. The amount of truck and vehicle trips would not conflict with an applicable congestion management program since the truck and vehicle trips would occur intermittently and largely outside of peak traffic hours. Additionally, the construction-related vehicle traffic would not approach 2,400 average daily trips or 200 peak hour trips, which would require a traffic study under SANDAG’s Congestion Management Program (County of San Diego Land Use and Environment Group 2011). Further, the proposed Project would not cause a change in existing long-term traffic patterns and would not add sufficient trips to degrade the existing levels of service or conflict with an applicable congestion management program. Therefore, the Project would have a less than significant impact. c. No Impact. The Project area is not located in the immediate vicinity of an airport or private airstrip. The nearest public airport, Brown Field Municipal Airport, is located approximately 8.2 miles from the Project area. The Project does not propose any activity that would be capable of altering existing air traffic patterns, levels, or locations associated with Brown Field Municipal Airport. Therefore, no impacts are anticipated to occur. d, e. Less than Significant. The proposed Project would not include any change to public roadway designs and would not introduce incompatible uses or line-of-sight issues. South Abutment Access Road improvements proposed under the Project would incorporate safe design to support a range of heavy construction vehicles; the privately accessible road would be extended and widened to a uniform width of 20 feet, with a 35-foot wide turnout along the road, and one 50-foot wide turnout/staging area near the dam. The Project would not conflict with an emergency response plan and traffic flows would not be significantly interrupted on any roadway such that they would impair or otherwise interfere with emergency access to local roads. The proposed Project would not result in traffic delays that could substantially increase emergency response times or reduce emergency vehicle access. Construction vehicles would not park on roadways and, thus, would not create a hazard, interrupt vehicle line-of-sight, or block emergency access. The Project does not propose any changes to a road that would have hazardous design features such as sharp curves or dangerous intersections, and would not result in inadequate emergency access. Therefore, the Project would have a less than significant impact. f. Less than Significant. The Sweetwater Riding and Hiking Trail traverses one of the proposed construction haul routes along Conduit Road and crosses the Conduit Road would be used for southern boundary of the South Dike Project area, delivery of construction materials and where trucks may pass across the trails during concrete to the base of the dam.
Page 99 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 construction activity. Recreational trail-crossing BMPs include regulating construction vehicle speed (e.g., less than 15 mph on unpaved roads), implementing dust control measures, maintaining trail access through construction, as outlined in MM REC-1 and REC-2, and repairing any trail segments that are damaged by construction to a condition equal to or better than that which existed prior to construction activity. No closures to trails, public transit, bicycle lanes, and pedestrian facilities would be required that would decrease the performance or safety of such facilities. During construction, a temporary trail detour for the Sweetwater Riding and Hiking Trail in the vicinity of the South Dike area would be required until proposed permanent trail realignment is open and accessible. Following the completion of the proposed permanent realignment, the temporary detour trail would be removed. The proposed Project would not adversely conflict with adopted policies, plans, or programs regarding public transit, bicycle, or pedestrian facilities, nor would it otherwise significantly decrease the performance or safety of such facilities. Therefore, the Project would have a less than significant impact.
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4.17 Tribal Cultural Resources
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project cause a substantial adverse change in the significance of a tribal cultural resource, defined in Public Resources Code Section 21074 as either a site, feature, place, cultural landscape that is geographically defined in terms of the size and scope of the landscape, sacred place, or object with cultural value to a California Native American tribe, and that is: a) Listed or eligible for listing in the California Register of Historical Resources, or in a local register
of historical resources as defined in Public Resources Code Section 5020.1(k). b) A resource determined by the lead agency, in its discretion and supported by substantial evidence, to be significant pursuant to criteria set forth in subdivision (c) of Public Resources Code Section
5024.1. In applying the criteria set forth in subdivision (c) of Public Resource Code Section 5024.1, the lead agency shall consider the significance of the resource to a California Native American tribe.
4.17.1 Existing Setting
Assembly Bill (AB) 52, which went into effect on July 1, 2015, established a consultation process with all California Native American Tribes on the NAHC List and required consideration of Tribal Cultural Values in the determination of Project impacts and mitigation. AB 52 established a new class of resources, tribal cultural resources, defined as a site feature, place, cultural landscape, sacred place or object, which is of cultural value to a Tribe that is either: (1) on or eligible for the California Historic Register or a local historic register; or (2) treated by the lead agency, at its discretion, as a traditional cultural resource per Public Resources Code 21074 (a)(1)(A)-(B).
Public Resources Code Section 21083.09, added by AB 52, required the California Natural Resources Agency to update Appendix G of the CEQA Guidelines to address tribal cultural resources. Pursuant to Government Code Section 11346.6, on August 8, 2016 the California Natural Resources Agency adopted and amended the CEQA Guidelines to include consideration
Page 101 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 of impacts to tribal cultural resources. These amendments separated the consideration of paleontological resources from tribal cultural resources and updated the relevant sample questions to add specific consideration of tribal cultural resources.
4.17.2 Discussion a, b. No Impact. As discussed in Section 4.5, Cultural Resources, the potential to discover an unknown tribal cultural resource within the Project site is highly unlikely. Previous disturbance of the Project site would have destroyed any potential tribal cultural resources that may have occurred beneath the surface. No evidence of tribal cultural resources has been identified within or adjacent to the project site and no “unexpected resources” are anticipated.
AB 52 requires lead agencies to consult with California Native American Tribes that request such consultation in writing prior to the agency's release of a Notice of Preparation (NOP) of an Environmental Impact Report (EIR); or notice of a Mitigated Negative Declaration (MND), or Negative Declaration (ND). No formal request for notification of projects or request consultation has been received. The Authority has complied with the requirements of AB 52 and the proposed Project would not result in any impacts to known tribal cultural resources.
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4.18 Utilities and Service Systems
Less Than Potentially Significant Less Than Significant With Significant No Impact Impact Mitigation Impact Incorporated Would the Project: a) Exceed wastewater treatment requirements of the applicable
Regional Water Quality Control Board? b) Require or result in the construction of new water or wastewater treatment facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? c) Require or result in the construction of new storm water drainage facilities or expansion of existing facilities, the construction of which could cause significant environmental effects? d) Have sufficient water supplies available to serve the project from existing entitlements and resources, or are new or expanded entitlements needed? e) Result in a determination by the wastewater treatment provider that serves or may serve the project that it has adequate
capacity to serve the project’s projected demand, in addition to the provider’s existing commitments? f) Be served by a landfill with sufficient permitted capacity to
accommodate the project’s solid waste disposal needs? g) Comply with federal, state and local statutes and regulations related to solid waste?
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4.18.1 Existing Setting
The Authority is the principal agency that manages operations of the Sweetwater Dam and provides water service to many San Diego County customers. The Robert A. Perdue Water Treatment Plant, which is adjacent to the Sweetwater Dam, treats water from the Sweetwater Reservoir before it is distributed to the Authority’s customers. There are utility lines for Sweetwater Dam along the face of the right abutment of the north parapet wall. Utilities include air, water, signal, and electrical lines. There are also air, water, and chemical feed lines near the right abutment stairs. Several utilities cross the right abutment at the deck level, near the 20-inch and 42-inch steel pipelines, and would conflict with construction and ultimately require re-routing to a final configuration; power and water at right abutment. A 220V power line is available at the left abutment. The Authority would coordinate with other public agencies that have easements or rights of way in the project area. All utility lines would remain in service throughout Project construction.
4.18.2 Discussion a. Less than Significant. Construction of the proposed project would generate a minimal volume of wastewater. During construction activities, wastewater would be contained within portable toilet facilities and disposed at an approved disposal site. The maintenance crew would utilize existing toilet facilities associated with the Fishing Program near the South Dike or a portable toilet. The proposed Project would implement a SWPPP to minimize the potential construction-related impacts of storm water on water quality in the Sweetwater Reservoir (refer to Section 4.9, Hydrology and Water Quality). The SWPPP would be retained on-site and updated as necessary in compliance with the NPDES for construction activity. As such, the proposed Project would not degrade water quality, and impacts to water quality would be less than significant. The Project would be required to adhere to NPDES permits, which specify requirements to protect the beneficial uses of all receiving waters and require permittees to develop and implement BMPs as discussed in Section 4.9, Hydrology and Water Quality Discussion, to control/reduce the discharge of pollutants to waters of the U.S. to the maximum extent practical. With adherence to these requirements, the proposed Project would include design measures to minimize potential impacts to receiving waters to less than significant levels. Thus, the Project would not result in wastewater discharges that would exceed the RWQCB’s requirements. Therefore, the proposed Project would have a less than significant impact. b – e. No Impact. The proposed Project would not require or result in the construction of new water or wastewater treatment facilities nor would it require the expansion of existing facilities. The proposed Project would not create or contribute runoff that would exceed the capacity of any storm water drainage systems in the Project area. The proposed Project includes construction and extension of segments of the South Abutment Access Road, which would create new gravel road surfaces. While a small rock drain would be constructed as a part of the South Abutment Access Road improvement, the widening of the road would not require new storm water drainage facilities (e.g., storm drain lines) or expansion of existing facilities. The proposed Project would not include any new development that would require public water supplies and no new or expanded water supply entitlements would be required for the Project. There is potential for minor service interruptions at Sweetwater Dam during Project construction; however, these minimal interruptions would not affect residents and local customers in obtaining water supplies from the
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Authority. The proposed Project would not generate wastewater and would not exceed capacity of Robert A. Perdue Water Treatment Plant. The Project would not result in the need for new or expanded water, storm water, or wastewater treatment facilities. Therefore, no impacts are anticipated to occur with the implementation of the proposed Project. f, g. Less than Significant. The Project would generate a limited amount of solid waste during construction and would not generate large quantities of solid waste on a long-term basis for dam operation and maintenance activities. Construction of the proposed Project would result in soil excavation, removal of existing deteriorating concrete surfaces at the South Spillway and north and south parapet walls, and minimal vegetation removal for the South Abutment Access Road and South Dike improvements. Waste concrete, demolished pipe and rebar, and other waste materials would be hauled off-site and recycled or disposed of at a local landfill in an appropriate manner. The contractor would be directed to divert all recyclable waste materials to the appropriate recycling centers. As such, the amount of material to be hauled off-site would not significantly affect the capacity of local landfills. The proposed Project would comply with all applicable federal, state, and local statutes and regulations related to solid waste and diversion from landfills. Therefore, the Project would have a less than significant impact.
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4.19 Mandatory Findings of Significance
Less Than Potentially Significant Less Than No Significant With Significant Impact Impact Mitigation Impact Incorporated a) Does the project have the potential to degrade the quality of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wild-life population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, reduce the number or restrict the range of rare or endangered plants or animals, or eliminate important examples of the major periods of California history or prehistory? b) Does the project have impacts that are individually limited, but cumulatively considerable? "Cumulatively considerable" means that the incremental effects of a project are
considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects. c) Does the project have environmental effects that will cause substantial adverse effects on human beings, either directly or indirectly?
4.19.1 Discussion
In order to achieve the Project objectives (refer to Section 1.4, Project Objectives and Scope), the Authority has proposed a number of improvements to the Sweetwater Dam and South Dike and associated improvements to Authority-maintained access roads and trails. Implementation of the proposed improvements would Comply with DSOD regulations contained in California Water Code Division 3, Dams and Reservoirs by modifying the Sweetwater Dam and South Dike to Page 106 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017 safely pass the PMF, and to prevent any public safety or public health hazards in the surrounding communities. a. Less Than Significant with Mitigation Incorporated. The analysis conducted in this Initial Study concludes that implementation of the proposed Project has the potential to have a significant impact on the environment. As evaluated in Section 4.4, Biological Resources and Section 4.5, Cultural Resources impacts on biological resources and cultural resources could be potentially significant; however, with the incorporation of mitigation measures, these impacts would be reduced below appropriate significance thresholds. Therefore, the proposed Project would not substantially degrade the quality of the environment; substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels; threaten to eliminate a plant or animal community; or reduce the number or restrict the range of an endangered, rare, or threatened species. In addition, the proposed Project would not eliminate important examples of California history. b. Less than Significant with Mitigation Incorporated. As discussed in this IS, the proposed Project would result in less than significant impacts or no impacts to aesthetics, agriculture and forestry resources, air quality, cultural resources, geology and soils, GHG emissions, hazards and hazardous materials, hydrology and water quality, mineral resources, noise, population and housing, public services, recreation, transportation and traffic, tribal cultural resources, and utilities and service systems.
With the implementation of mitigation measures, as described in Section 4.4, Biological Resources, Section 4.5, Cultural Resources, Section 4.12, Noise, and 4.15, Recreation, impacts associated with the implementation of the proposed Project would be less than significant. None of the proposed Project’s impacts make cumulatively considerable, incremental contributions to significant cumulative impacts. c. Less than Significant with Mitigation Incorporated. Construction of the proposed Project would generate noise and produce air emissions. However, with incorporation of MM NOI-1, the impacts to construction workers and surrounding residents would be reduced to less than significant levels. The proposed Project would not cause substantial adverse effects on human beings, either directly or indirectly. With mitigation measures incorporated, impacts would be less than significant.
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5.0 REFERENCES
Alta Planning & Design. 2003. “County of San Diego Bicycle Transportation Plan.” http://www.sandiegocounty.gov/dplu/docs/Bicycle_Transportation_Plan.pdf.
Amec Foster Wheeler Environment & Infrastructure, Inc. (Amec Foster Wheeler). 2017. Draft Phase I Cultural Resources Inventory Sweetwater Dam and South Dike Improvements Project Near the Community of Bonita San Diego County, California.
California Department of Conservation (CDC). 2015. “CGS Information Warehouse.” http://maps.conservation.ca.gov/cgs/informationwarehouse/index.html?map=regulatorym aps.
———. 2014. “San Diego County, California Important Farmland Finder.” http://maps.conservation.ca.gov/ciff/ciff.html.
California Department of Forestry and Fire Protection (Cal Fire). 2007. “San Diego County Fire Hazard Severity Zones in State Responsibility Area.” http://frap.fire.ca.gov/webdata/maps/san_diego/fhszs_map.37.pdf.
California Department of Transportation (Caltrans). 2016. “Transportation Concept Report for State Route 125, District 11.” http://www.dot.ca.gov/dist11/departments/planning/pdfs/tcr/2016_TCR_SR_125.pdf.
California Air Pollution Control Officers Association (CAPCOA). 2008. “CEQA and Climate Change.” http://www.capcoa.org/wp-content/uploads/2012/03/CAPCOA-White- Paper.pdf.
California Air Resources Board (CARB). 2016. “California’s Greenhouse Gas Emission Inventory.” http://www.arb.ca.gov/cc/inventory/data/data.htm.
———. 2014. “Assembly Bill 32 - California Global Warming Solutions Act.” https://www.arb.ca.gov/cc/ab32/ab32.htm.
County of San Diego. 2017. “Earthquake Facts and Preparedness.” http://www.sandiegocounty.gov/oes/disaster_preparedness/oes_jl_earthquakes.html.
———. 2016. “County of San Diego Watershed Protection, Stormwater Management, and Discharge Control Ordinance.” http://www.sandiegocounty.gov/content/sdc/dpw/watersheds/ordinance.html.
———. 2014. “Sweetwater Community Plan - San Diego County General Plan.” http://www.sandiegocounty.gov/pds/docs/CP/Sweetwater_CP.pdf.
———. 2012. “San Diego County Grading Ordinance.” http://www.sandiegocounty.gov/content/dam/sdc/dpw/LAND_DEVELOPMENT_DIVISIO N/landpdf/gradingordinance.pdf.
———. 2011a. “General Plan - Mobility Element, Chapter 4.” http://www.sandiegocounty.gov/content/dam/sdc/pds/gpupdate/docs/GP/MobilityElement .pdf.
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———. 2011b. “General Plan Update FEIR - Chapter 2.1 Aesthetics.” http://www.sandiegocounty.gov/content/dam/sdc/pds/gpupdate/docs/BOS_Aug2011/EIR /FEIR_2.01_-_Aesthetics_2011.pdf.
———. 2011c. “General Plan Update FEIR - Chapter 2.7 Hazards and Hazardous Materials.” http://www.sandiegocounty.gov/content/dam/sdc/pds/gpupdate/docs/BOS_Aug2011/EIR /FEIR_2.07_-_Hazards_2011.pdf.
———. 2008. “Noise Control and Abatement Ordinance - County Code Section 36.409.”
County of San Diego Land Use and Environment Group. 2011. “County of San Diego Guidelines for Determining Significance and Report Format and Content Requirements, Transportation and Traffic.” http://www.sandiegocounty.gov/dplu/docs/Traffic_Guidelines.pdf.
County of San Diego Planning and Development Services. 2012. “General Plan and Zoning Map.” https://www.arcgis.com/home/webmap/viewer.html?webmap=f1b69ba9d3dd4940b8d1ef cc9dac2ac4.
Cunniff, P. 1977. "Environmental Noise Pollution."
Department of Toxic Substances Control (DTSC). 2017. “EnviroStor Database Search Tool.” http://www.envirostor.dtsc.ca.gov/.
———. 2007. “Hazardous Waste and Substances Site List - Site Cleanup (Cortese List).” http://www.envirostor.dtsc.ca.gov/.
Division of Safety of Dams (DSOD). 1981. Hydrology Manual-Flood Estimates for Dams Sacramento: California Department of Water Resources.
ESA. 2013. “Sweetwater Reservoir Wetlands Habitat Recovery Project Initial Study / Mitigated Negative Declaration.”
Famolaro, P. 2017. Personal Communication with Pete Famolaro, Sweetwater Watershed Manager on May 11, 2017.
Federal Emergency Management Agency (FEMA). 2012. “FEMA Flood Map Service Center - Sweetwater Dam.” https://msc.fema.gov/portal/search?AddressQuery=Sweetwater%20Dam%20#searchres ultsanchor.
GEI Consultants, Inc. (GEI). 2016. Draft Sweetwater Dam and South Dike Improvements Midpoint Design Report. Submitted to Sweetwater Authority, June 10.
———. 2015a. Preliminary Design of Sweetwater Dam and South Dike Modifications to Accommodate a Probable Maximum Flood, submitted to Sweetwater Authority, June 30.
———. 2015b. Sweetwater South Dike Modifications, Geotechnical Data Report, submitted to Sweetwater Authority, June (Draft).
Page 109 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
———. 2013. Updated Probable Maximum Flood for Sweetwater Main Dam, Submitted to Sweetwater Authority, February 18.
Gutierrez, D. Sweetwater Dam Probable Maximum Flood and South Spillway Improvements. Division of Safety and Dams September 26, 2016. Available at: http://www.sweetwater.org/Modules/ShowDocument.aspx?documentid=8649.
Kennedy, M.P., and S.S. Tan. 1977. “Geology of National City, Imperial Beach, and Otay Mesa Quadrangles, Southern San Diego Metropolitan Area, California.” California Division of Mines and Geology, The Resources Agency Department of Conservation.
Mikesell, Stephen D., 1998. Historic Resources Evaluation Report Sweetwater Dam NC&O Sweetwater Branch Sweetwater Quarries.
Regional Water Quality Control Board (2017). “San Diego Region – The Basin Plan” http://www.waterboards.ca.gov/sandiego/water_issues/programs/basin_plan/index.shtml
RECON. 2002. Letter Report for the Sweetwater Reservoir Landfill Expansion Project. July 17.
San Diego County Water Authority. 2016. “Reservoirs.” http://www.sdcwa.org/reservoirs.
San Diego Regional Water Quality Control Board. 2016. “Water Quality Control Plan for the San Diego Region - The Basin Plan.” http://www.waterboards.ca.gov/sandiego/water_issues/programs/basin_plan/index.shtml
National Weather Service (NWS). 1999. Hydrometeorological Report No. 59, Probable Maximum Precipitation for California, United States Department of Commerce, National Oceanic and Atmospheric Administration, United States Department of the Army, Corps of Engineers, Silver Spring, MD, February.
Ninyo & Moore. 2005. Draft Geotechnical Evaluation, Perdue Water Treatment Plan Modifications, Spring Valley, California. July 18.
National Weather Service (NWS). 1998. Hydrometeorological Report No. 58, Probable Maximum Precipitation for California, United States Department of Commerce, National Oceanic and Atmospheric Administration, United States Department of the Army, Corps of Engineers, Silver Spring, MD, October.
———. 1977. Hydrometeorological Report No. 49, Probable Maximum Precipitation Estimates, Colorado River and Great Basin Drainage, September.
———. 1969. Hydrometeorological Report No. 36, Probable Maximum Precipitation in California, October 1961 (Including October Revisions).
Ninyo & Moore. 2011. Geotechnical Evaluation, South Dike Fill Site, San Diego County, CA, May 6.
Preston K.L., P.J. Mock, M.A. Grishaver, E.A. Bailey, and D.F. King. 1998. California territorial behavior. Western Birds 29: 242-257.
Page 110 Sweetwater Authority Draft Initial Study / Mitigated Negative Declaration Sweetwater Dam and South Dike Improvements Project November 2017
Sweetwater Authority (Authority). 2001. Final Supplement to the Final Environmental Impact Report for the Sweetwater Reservoir Recreation Master Plan Shoreline Fishing Program. County of San Diego Permit Number MUP 01-02, State Clearinghouse Number 1985101602. Prepared by Sweetwater Authority. December 2001
———. 2017a. “Shoreline Fishing Rules and Regulations.” http://www.sweetwater.org/DocumentCenter/View/484.
———. 2017b. Updated Strategic Plan. http://www.sweetwater.org/Modules/ShowDocument.aspx?documentid=4150.
State Water Resources Control Board (SWRCB). 2016. “State Water Board Staff Final 2012 California Integrated Report (Clean Water Act Section 303 (D) List / 305(b) Report.” http://www.waterboards.ca.gov/water_issues/programs/tmdl/integrated2012.shtml.
Tan, S.S. 1992. Landslide Hazards in the Jamul Mountains Quadrangle, San Diego County, CA. Open File Report 92-12. California Department of Conservation, Division of Mines and Geology (now California Geological Survey).
———. 2002. Geologic Map of the Jamul Mountains 7.5’Quadrangle, San Diego County, CA. California Department of Conservation, California Geological Survey.
Todd, V. R. 2004. Preliminary Map of the El Cajon 30’ x 60’ Quadrangle, Southern California, Version 1.0. Open File Report 2004-1361. U.S. Geological Survey.
U.S. Department of Agriculture (USDA). 2017. “USDA-NRCS Soil Series Classification View By Name.” https://soilseries.sc.egov.usda.gov/scname.aspx.
U.S. Environmental Protection Agency (USEPA). 1971. “Noise from Construction Equipment and Operations, Building Equipment, and Home Appliances.” https://nepis.epa.gov/.
———. 2005. “Proposed Rule To Implement the Fine Particle National Ambient Air Quality Standards.” https://www.federalregister.gov/articles/2005/11/01/05-20455/proposed-rule- to-implement-the-fine-particle-national-ambient-air-quality-standards.
———. 2006. “Documentation for the Final 2002 Nonpoint Sector (Feb 06 Version) National Emission Inventory for Criteria and Hazardous Air Pollutants.”
U.S. Fish and Wildlife Service (USFWS). 2017. “Critical Habitat Mapper.” http://fws.maps.arcgis.com/home/webmap/viewer.html?webmap=9d8de5e265ad4fe0989 3cf75b8dbfb77.
———. 2016. “San Diego National Wildlife Refuge.” https://www.fws.gov/refuge/San_Diego/about.html.
———. 2010. Coastal California gnatcatcher 5-year Review. U.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office, Carlsbad, California. September 29, 2010.
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