Ogier Ponds Feasibility Study Feasibility of Removing Surface Hydraulic Connection Between Coyote Creek and Ogier Ponds, Santa Clara County, California March, 2018 Attachment 2 Page 1 of 138 Ogier Ponds Feasibility Study THIS PAGE INTENTIONALLY LEFT BLANK i Attachment 2 Page 2 of 138 Ogier Ponds Feasibility Study TABLE OF CONTENTS Page Authors ...................................................................................................................................... 1 Executive Summary ................................................................................................................... 2 1. Introduction ........................................................................................................................... 7 1.1. Study Background and Scope ...................................................................................... 7 1.2. Study Objectives & Approach ....................................................................................... 9 2. Site Location and Past and Current Uses .............................................................................13 2.1. Site Location and Ownership .......................................................................................13 2.2. Past Site Use ..............................................................................................................16 2.3. Current Site Use ..........................................................................................................19 3. Issues ...................................................................................................................................21 3.1. Ecology .......................................................................................................................21 3.1.1. Historical Ecology .....................................................................................................21 3.1.2. Current Ecological Condition ....................................................................................23 3.1.3. Fish ..........................................................................................................................26 3.1.4. Birds .........................................................................................................................31 3.1.5. Odonates ..................................................................................................................35 3.1.6. Amphibians ..............................................................................................................35 3.1.7. Reptiles ....................................................................................................................36 3.1.8. Ecological Consequences ........................................................................................37 3.2. Surface Water Quality .................................................................................................39 Temperature .......................................................................................................................40 Continuous Surface Water Quality Monitoring Results ........................................................45 Temperature and Oxygen Profiles .......................................................................................49 Water Temperature Effects .................................................................................................52 Pond 5 2017 Bloom .............................................................................................................52 Water Quality Consequences of Pond-creek Separation .....................................................56 3.3. Water Supply and Water Rights ..................................................................................58 3.3.1. Water Supply Infrastructure and Operations .............................................................58 3.3.2. Groundwater Conditions ...........................................................................................62 3.3.3. Groundwater Pumping and Managed Recharge .......................................................65 3.3.4. Groundwater Quality .................................................................................................65 3.3.5. Water Rights.............................................................................................................66 3.4. Potential for Managed Groundwater Recharge ............................................................68 3.5. Potential for Flood Attenuation ....................................................................................73 3.5.1. Background, Methodology and Analysis ....................................................................73 Approach and Methodology .................................................................................................74 3.5.2. Results .....................................................................................................................86 3.5.3. Flood Attenuation Conclusion ...................................................................................90 3.6. Pond sustainability ......................................................................................................91 3.6.1. Review of Historical Aerial Photography ...................................................................91 ii Attachment 2 Page 3 of 138 Ogier Ponds Feasibility Study 3.6.2. Pond Water Balance ............................................................................................... 102 3.6.3. Pond Water Balance Under Existing Condition ....................................................... 104 3.6.4. Pond Water Balance under Pre-1997 Channel Restoration Concept ...................... 105 3.6.5. Ponds Water Balance with Floodplain Restoration Concept ................................... 107 3.7. Recreation ................................................................................................................. 108 3.7.1. Recreational Setting ............................................................................................... 108 3.7.2. Integrated Plan Guidelines ..................................................................................... 109 3.7.3. Existing Recreation Uses........................................................................................ 110 3.7.4. Analysis of Concepts .............................................................................................. 114 3.8. Implementation Costs ................................................................................................ 117 Pre-1997 Channel Restoration Concept ............................................................................ 117 Floodplain Restoration Concept ........................................................................................ 118 4. Comparison of Concepts .................................................................................................... 120 5. References......................................................................................................................... 123 Appendices ............................................................................................................................. 127 APPENDICES Appendix A: Groundwater Report................................................................................................. Appendix B: Ecological Report ..................................................................................................... Appendix C: Planning, Design, Permitting and Implementation Cost Spreadsheets ..... 129—133 LIST OF FIGURES Figure 1: Regional Map ................................................................................................. 7 Figure 2: Pre-1997 Channel Restoration Concept ....................................................... 10 Figure 3: Floodplain Restoration Concept ................................................................... 11 Figure 4: Map of Creek, Canal, and Pond Configuration in Study Area ....................... 14 Figure 5: Historical Aerial Imagery (1939) .................................................................. 16 Figure 6: Historical Habitats in Coyote Valley. ........................................................... 20 Figure 7: Local Alluvial Fan Deposition from Diablo Range Tributaries ....................... 22 Figure 8: Changes in Channel and Floodplain Morphology Over Time Due to Upstream Reservoirs and Changes in Adjacent Land Use ........................................... 23 Figure 9: Locations of the Six Temperature Monitoring Stations and Five Multi- Parameter Sampling Points .......................................................................... 38 Figure 10: Coyote Creek Temperature Stations 31, 29, and 28: WY 2002 ................... 39 Figure 11: Coyote Creek Temperature Stations 31, 29, and 28: WY 2005 ................... 40 Figure 12: Coyote Creek Temperature Stations 31, 29, and 28: WY 2008 ................... 40 Figure 13: Coyote Creek Temperature Stations 31, 29, and 28: WY 2009 ................... 41 Figure 14: Coyote Creek Temperature Stations 31 and 28: WY 2010 .......................... 41 Figure 15: Coyote Creek Temperature Stations 31 and 28: WY 2011 .......................... 42 Figure 16: Coyote Creek Temperature Stations 31 and 28: WY 2012 .......................... 42 Figure 17: Temperature (°C) in Coyote Creek and Ogier Ponds ................................... 43 Figure 18: Coyote Creek Stations 31 and 28: October