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 ..............................................................................................