Russian River Hydrologic Modeling for the Fish Habitat Flows and Water Rights Project August 2016 Prepared by: Sonoma County Water Agency 404 Aviation Boulevard Santa Rosa, CA 95406 Contact: Chris Delaney 707-547-1946 Suggested Reference Sonoma County Water Agency. 2016. Russian River Hydrologic Modeling for the Fish Habitat Flows and Water Rights Project. August 2016. American Disabilities Act Compliance This Draft Environmental Impact Report for the Sonoma County Water Agency’s Fish Habitat Flows and Water Rights Project has been prepared to be compliant with requirements under the Americans with Disabilities Act (ADA). The ADA mandates that reasonable accommodations be made to reduce "discrimination on the basis of disability." As such, the Sonoma County Water Agency is committed to ensuring that documents we make publicly available online are accessible to potential users with disabilities, particularly blind or visually impaired users who make use of screen reading technology. This disclaimer is provided to advise that portions of the document, including the figures, charts, and graphics included in the document, are non-convertible material, and could not reasonably be adjusted to be fully compliant with ADA regulations. For assistance with this data or information, please contact the Water Agency, at (707) 526- 5370 and reference the Draft Environmental Impact Report for the Sonoma County Water Agency’s Fish Habitat Flows and Water Rights Project, dated July 2016. Table of Contents Suggested Reference ............................................................................................................. 2-1 American Disabilities Act Compliance ..................................................................................... 2-1 1 Introduction...................................................................................................................... 2-1 1.1 Purpose and Scope .................................................................................................. 2-1 1.2 Model Overview ........................................................................................................ 2-1 2 Background...................................................................................................................... 2-2 2.1 Russian River System............................................................................................... 2-2 2.1.1 System Reaches................................................................................................ 2-2 2.1.2 Climate .............................................................................................................. 2-4 2.1.3 Potter Valley Project .......................................................................................... 2-6 2.1.4 Lake Mendocino .............................................................................................. 2-10 2.1.5 Lake Sonoma................................................................................................... 2-14 2.1.6 Russian River System Water Supply Operations ............................................. 2-17 2.2 Fish Habitat Flows EIR ........................................................................................... 2-24 2.2.1 Russian River Biological Opinion ..................................................................... 2-24 2.2.2 Minimum Instream Flow Alternatives ............................................................... 2-25 2.2.3 Hydrologic Index .............................................................................................. 2-26 3 Russian River ResSim ..................................................................................................... 3-1 3.1 System Gains ........................................................................................................... 3-4 3.1.1 USGS Unimpaired Flows ................................................................................... 3-4 3.1.2 Potter Valley Project Diversions....................................................................... 3-11 3.2 System Losses ....................................................................................................... 3-17 3.2.1 Municipal Water Demands............................................................................... 3-18 3.2.2 Agricultural Demands....................................................................................... 3-19 3.2.3 Water Balance Losses..................................................................................... 3-19 3.2.4 Water Losses Due to Frost Protection ............................................................. 3-20 3.2.5 Water Loss Year Types ................................................................................... 3-24 3.2.6 Reservoir Surface Evaporation ........................................................................ 3-25 3.3 Flow Routing........................................................................................................... 3-26 3.4 Reservoir Storage Capacity .................................................................................... 3-27 3.4.1 Lake Mendocino .............................................................................................. 3-27 i 3.4.2 Lake Sonoma................................................................................................... 3-28 3.4.3 Reservoir Storage Projections ......................................................................... 3-29 3.5 System Operations ................................................................................................. 3-30 3.5.1 Flood Control Operations................................................................................. 3-30 3.5.2 Reservoir Emergency Operations .................................................................... 3-31 3.5.3 Water Supply Operations................................................................................. 3-32 3.5.4 Fish Hatchery Operations ................................................................................ 3-42 3.5.5 Hydroelectric Power Generation ...................................................................... 3-42 3.6 River Stage............................................................................................................. 3-47 3.7 RR ResSim Model Verification................................................................................ 3-47 3.7.1 Verification Simulation Setup ........................................................................... 3-48 3.7.2 Verification Simulation Results......................................................................... 3-49 4 Russian River Water Quality Model.................................................................................. 4-1 5 Model Results ..................................................................................................................5-1 6 References ...................................................................................................................... 6-1 List of Figures Figure 2-1. Map of the Russian River watershed including the Potter Valley Project............... 2-3 Figure 2-2. 30-year average annual rainfall for the Russian River watershed.......................... 2-5 Figure 2-3. Map of the Potter Valley Project............................................................................ 2-8 Figure 2-4. Lake Pillsbury Target Storage Curves in acre-feet. ............................................... 2-9 Figure 2-5. Lake Mendocino Average annual inflow in acre-feet per year for periods both prior to the implementation of the PVP FERC license amendment in the fall of 2006........................ 2-10 Figure 2-6. Lake Mendocino Pool Schedules in acre-feet defined in the 2004 Water Control Diagram. ............................................................................................................................... 2-12 Figure 2-7. Lake Sonoma Pool Schedules in acre-feet defined in the 1984 Water Control Manual.................................................................................................................................. 2-14 Figure 2-8. Lake Sonoma usable and sediment storage allocation in acre-feet..................... 2-16 Figure 2-9. Russian River System Hydrologic Index and minimum instream flow requirements defined in the Water Agency’s water rights permits............................................................... 2-19 Figure 3-1. Schematic of Russian River ResSim with model junction locations and the locations of defined system gain and loss boundary conditions.............................................................. 3-3 Figure 3-2. Scatter plot of 1959 to 2013 December to April Lake Mendocino unimpaired inflow volumes simulated by the USGS versus observed Lake Mendocino inflow volumes............... 3-5 Figure 3-3. Percent exceedance of 1959 to 2013 December to April Lake Mendocino unimpaired inflow volumes simulated by the USGS and observed local flows......................... 3-5 ii Figure 3-4. Scatter plot of 1959 to 2013 December to April Upper Russian River unimpaired inflow volumes simulated by the USGA versus observed Upper Russian River inflow volumes. 3- 6 Figure 3-5. Percent exceedance of 1959 to 2013 December to April Upper Russian River unimpaired inflow volumes simulated by the USGS and observed local inflow volumes.......... 3-7 Figure 3-6. Scatter plot of 1989 to 2013, December to April Lake Sonoma unimpaired inflow volumes simulated by the USGS