INITIAL STUDY FOR THE COTTAGE CREEK DAM MODIFICATION PROJECT Prepared for: Yuba Water Agency 1220 F Street Marysville, CA 95901 Prepared by: 9888 Kent Street Elk Grove, CA 95624 (916) 714-1801 August 2020 INITIAL STUDY TABLE OF CONTENTS SECTION PAGE 1 INTRODUCTION ................................................................................................................................................. 1 1.1 Project Overview ..................................................................................................................................... 1 1.2 Regulatory Guidance .............................................................................................................................. 1 1.3 Public Review ......................................................................................................................................... 1 1.4 Summary of Findings .............................................................................................................................. 2 1.5 Document Organization .......................................................................................................................... 3 2 PROJECT DESCRIPTION .................................................................................................................................. 3 2.1 Project Location ...................................................................................................................................... 3 2.2 Project History and Background ............................................................................................................. 6 2.3 Project Purpose ...................................................................................................................................... 7 2.4 Proposed Project .................................................................................................................................... 8 2.4.1 Project Description Overview .................................................................................................. 8 2.4.2 Mobilization ............................................................................................................................. 8 2.4.3 Clearing and Grubbing ............................................................................................................ 9 2.4.4 Rerouting Cottage Creek Flows and Dewatering the Reservoir ............................................. 9 2.4.5 Excavate Dam and Remove Existing Corrugated Metal Pipe Spillway and Downstream Culvert .................................................................................................................................. 11 2.4.6 Install Concrete Culvert ........................................................................................................ 11 2.4.7 Demobilization ...................................................................................................................... 12 2.4.8 Schedule ............................................................................................................................... 12 2.4.9 Avoidance and Minimization Measures ................................................................................ 13 3 ENVIRONMENTAL CHECKLIST ...................................................................................................................... 16 3.1 Aesthetics ............................................................................................................................................. 17 3.1.1 Setting................................................................................................................................... 17 3.1.2 Discussion ............................................................................................................................ 18 3.2 Agriculture and Forestry Resources ..................................................................................................... 19 3.2.1 Setting................................................................................................................................... 19 3.2.2 Discussion ............................................................................................................................ 19 3.3 Air Quality ............................................................................................................................................. 20 3.3.1 Setting................................................................................................................................... 20 3.3.2 Discussion ............................................................................................................................ 27 3.4 Biological Resources ............................................................................................................................ 30 3.4.1 Setting................................................................................................................................... 30 3.4.2 Discussion ............................................................................................................................ 40 3.5 Cultural Resources ............................................................................................................................... 51 Cottage Creek Dam Modification Project Robertson-Bryan, Inc. Yuba Water Agency i Initial Study INITIAL STUDY TABLE OF CONTENTS SECTION PAGE 3.5.1 Setting................................................................................................................................... 51 3.5.2 Discussion ............................................................................................................................ 54 3.6 Energy .................................................................................................................................................. 56 3.6.1 Setting................................................................................................................................... 56 3.6.2 Discussion ............................................................................................................................ 56 3.7 Geology/Soils ........................................................................................................................................ 57 3.7.1 Setting................................................................................................................................... 58 3.7.2 Discussion ............................................................................................................................ 59 3.8 Greenhouse Gas Emissions ................................................................................................................. 60 3.8.1 Setting................................................................................................................................... 60 3.8.2 Discussion ............................................................................................................................ 63 3.9 Hazards & Hazardous Materials ........................................................................................................... 64 3.9.1 Setting................................................................................................................................... 65 3.9.2 Discussion ............................................................................................................................ 65 3.10 Hydrology/Water Quality ....................................................................................................................... 66 3.10.1 Setting................................................................................................................................... 67 3.10.2 Discussion ............................................................................................................................ 68 3.11 Land Use/Planning ............................................................................................................................... 74 3.11.1 Setting................................................................................................................................... 74 3.11.2 Discussion ............................................................................................................................ 74 3.12 Mineral Resources ................................................................................................................................ 75 3.12.1 Setting................................................................................................................................... 75 3.12.2 Discussion ............................................................................................................................ 75 3.13 Noise ..................................................................................................................................................... 75 3.13.1 Setting................................................................................................................................... 76 3.13.2 Discussion ............................................................................................................................ 78 3.14 Population/Housing ............................................................................................................................... 82 3.14.1 Setting..................................................................................................................................