SCOTT VALLEY COMMUNITY GROUNDWATER STUDY PLAN Prepared by Thomas Harter, Ph.D., and Ryan Hines Groundwater Cooperative Extension Program University of California, Davis With the Assistance of: Scott River Watershed Council Water Committee Siskiyou Resource Conservation District Staff North Coast Regional Water Quality Control Board Staff Prepared for: North Coast Regional Water Quality Control Board Siskiyou County Resource Conservation District Siskiyou County Board of Supervisors With funding by: State Water Resources Control Board FINAL REPORT Version H, February 11, 2008 ACKNOWLEDGMENTS Preparation of this Draft Study Plan was assisted by the following people: Scott River Watershed Council Water Committee members Jim De Pree, Siskiyou County, Natural Resource Policy Specialist Marc Horney, Ph.D., Natural Resource Conservation Service Steve Orloff, UC Cooperative Extension – Yreka Office Sari Sommarstrom, Ph.D., watershed management consultant, Etna Siskiyou Resource Conservation District Staff Danielle Quigley (former staff) Erich Yokel North Coast Regional Water Quality Control Board staff Bryan McFadin, P.E., Scott River TMDL Coordinator This is the Scott Valley Community Groundwater Study Plan. An electronic copy of this Plan can be obtained from the following website: http://groundwater.ucdavis.edu/ScottValley.htm For further inquiries, please contact Ryan Hines, [email protected] or Thomas Harter, [email protected] . Thomas Harter, Ph.D. 125 Veihmeyer Hall University of California Davis, CA 95616-8628 Phone: 530-752-2709 ii Table of Content 1 INTRODUCTION ...................................................................................................... 1 1.1 Background......................................................................................................... 1 1.2 Format of the Groundwater Study Plan .............................................................. 2 1.3 Role of Water Quality Planning.......................................................................... 2 2 GOALS & OBJECTIVES........................................................................................... 4 2.1 Community-Identified Goals.............................................................................. 4 2.2 Stakeholder Expectations.................................................................................... 5 2.3 Hypotheses / Study Elements.............................................................................. 7 2.3.1 Scott Valley Water Balance........................................................................ 8 2.3.2 Groundwater Levels.................................................................................... 8 2.3.3 Groundwater-Surface Water Connection.................................................... 8 2.3.4 Vegetation-Hydrology ................................................................................ 9 2.3.5 Stream Temperature and Its Controls ....................................................... 10 2.3.6 Additional Research Questions................................................................. 10 3 BACKGROUND: CURRENT SCOTT VALLEY CONDITIONS ......................... 11 3.1 Physical Setting................................................................................................. 12 3.1.1 Geography of the Scott Valley.................................................................. 12 3.1.2 Climate, Temperature, and Precipitation .................................................. 12 3.1.3 Geologic Setting........................................................................................ 13 3.1.4 Soil Characteristics................................................................................... 15 3.1.5 Watershed Characteristics......................................................................... 16 3.2 Hydrology and Water Balance of the Scott Valley........................................... 18 3.2.1 Surface Water Resources: Streams, Lakes, Diversions ............................ 18 3.2.2 Stream Channel Characteristics of the Scott River Mainstem.................. 20 3.2.3 Groundwater Aquifers.............................................................................. 22 3.2.4 Groundwater Storage................................................................................ 23 3.2.5 Historic Groundwater Levels and Fluctuations ........................................ 24 3.2.6 Water Quality............................................................................................ 28 3.2.7 Water Balance........................................................................................... 31 3.3 Biological Setting..............................................................................................33 3.3.1 Adult spawning of Chinook and coho salmon in Scott River................... 37 3.4 Water Use Setting ............................................................................................. 37 3.5 Water Management in the Scott Valley............................................................ 41 3.5.1 Scott River Water Rights and Adjudication.............................................. 42 3.5.2 Scott River Dry and Critically-Dry Year Plan.......................................... 43 3.5.3 Scott River Water Trust ............................................................................ 44 4 GROUNDWATER DYNAMICS IN THE SCOTT VALLEY ................................ 44 4.1 The Scott River as Groundwater Dependent Ecosystems (GDE): Basic Concepts of Groundwater – Surface Water Interactions and their Ecological Importance .................................................................................................................... 44 4.2 Groundwater Flow and Heat Transport – A Preliminary Conceptual Outline . 49 4.3 Flow and Heat Transport at the Groundwater-Stream Interface....................... 51 5 STUDY PLAN ELEMENTS (RESEARCH METHODS)....................................... 52 Scott Valley Groundwater Study Plan iii 2/11/2008 5.1 Field Data Collections and Field Data Analysis............................................... 52 5.1.1 Groundwater Level Observations ............................................................. 52 5.1.2 Surface Water Discharge Monitoring ....................................................... 54 5.1.3 Mapping Stream Topography and Morphology ....................................... 55 5.1.4 Near- and In-Stream Monitoring Well- / Piezometer Nest-Network........ 56 5.1.5 Tracer and Isotope Studies to Quantify Groundwater-Surface Water Interactions................................................................................................................ 57 5.1.6 Monitoring Groundwater Temperature in/near Streams........................... 58 5.1.7 Monitoring Stream Temperature............................................................... 60 5.1.8 Monitoring Groundwater Pumping........................................................... 61 5.1.9 Hydraulic Groundwater Tests: Pumping Tests and Slug Tests ................ 63 5.1.10 Geophysical Surveys................................................................................. 63 5.1.11 Groundwater Recharge............................................................................. 64 5.1.12 Valley Water Balance: Groundwater and Surface Water Use.................. 65 5.1.13 Spatio-temporal Distribution of Up-/Downward Seepage in Streambeds 66 5.2 Groundwater Modeling Approaches................................................................. 67 5.2.1 Model Design and Objectives................................................................... 67 5.2.2 Phase I Groundwater Flow Model ............................................................ 69 5.2.3 Thermal Fluxes and Linkage to Flow Models .......................................... 72 5.3 Assessment of the Impact of Various BMPs to Beneficial Uses...................... 73 5.3.1 Definition of BMPs and Management Approaches.................................. 73 5.3.2 Evaluating Water Management: Dealing with Data Paucity and Uncertainty................................................................................................................ 73 6 ROAD MAP and COST ESTIMATES..................................................................... 76 7 SCOTT VALLEY ENVIRONMENT: LIST OF AVAILABLE RESOURCES...... 80 7.1 Scott River Plans............................................................................................... 80 7.2 Groundwater ..................................................................................................... 81 7.3 Temperature ...................................................................................................... 81 7.4 Fish.................................................................................................................... 81 7.5 Water Balance................................................................................................... 82 7.6 Water Use.......................................................................................................... 82 7.7 Water Rights Adjudications.............................................................................. 83 7.8 Riparian Vegetation.......................................................................................... 83 7.9 Sediment and Geomorphology ........................................................................ 84 7.10 Natural Resources ............................................................................................