Scientific Basis Report in Support of New and Modified Requirements for Inflows from the Sacramento River and its Tributaries and Eastside Tributaries to the Delta, Delta Outflows, Cold Water Habitat, and Interior Delta Flows

California State Water Resources Control Board (SWRCB) | October 2nd, 2017

The State Water Board is conducting a review and update of the 2006 Bay-Delta Plan to ensure that beneficial uses of water in the Bay-Delta watershed are reasonably prote

The State Water Board is conducting a review and update of the 2006 Bay-Delta Plan to ensure that beneficial uses of water in the Bay-Delta watershed are reasonably protected. Phase I addresses potential changes to San Joaquin River flow requirements for the protection of fish and wildlife and potential changes to southern Delta salinity requirements for the protection of agriculture.1 Phase II addresses changes to the Bay-Delta Plan to protect native fish and wildlife in the Sacramento River, Delta, and associated tributaries. This Scientific Basis Report (Science Report or Report) is being prepared to support the Phase II update of the Bay-Delta Plan. It describes the science on which proposed changes to the Bay-Delta Plan will be based. A working draft version of the Report was released on October 19, 2016, to receive early scientific and public input on the science related to Phase II prior to submittal of the Report for external peer review. The State Water Board received input from a number of interested parties including water users; environmental groups; and local, state, and federal agencies. In recognition of the vision for “one Delta, one science” articulated in the Delta Stewardship Council’s (DSC) Delta Plan, the State Water Board also requested that the Delta Independent Science Board (Delta ISB) conduct a review of the Report. The State Water Board appreciates the valuable comments and suggestions that have helped further strengthen the scientific content in this version of the Report. In addition, comments related to regulatory and policy issues were raised that have further informed the development of proposed changes to the Bay-Delta Plan, including implementation approaches. The general components of these changes are summarized below and in more detail in Chapter 5 for context, and will continue to be refined as the planning process moves forward. This Report and the peer reviewers’ responses will be posted on the State Water Board web site and become part of the record for this Bay-Delta Plan update. Content from this Report will be included in a larger Staff Report that will also contain information on environmental, economic, and other analyses of potential changes to the Bay-Delta Plan, including regulatory and policy considerations of competing uses of water (including municipal, industrial, agricultural, power production, and other environmental uses of water such as wetland and wildlife refuge supplies). These issues are not addressed in this Science Report. Further, while a description of the approach for proposed changes to the Bay-Delta Plan is provided, the exact regulatory language is still under development and will be informed by the science in this Report and other information that will be included in the Staff Report. The public and agencies will continue to have opportunities to provide input throughout this process.

Scientist and Stakeholder Views on the Delta Ecosystem

Public Policy Institute of California (PPIC) | April 22nd, 2013

There is broad scientific recognition that a wide range of ecosystem stressors are responsible for the declines in native fish populations in the Sacramento–San Joaquin

There is broad scientific recognition that a wide range of ecosystem stressors are responsible for the declines in native fish populations in the Sacramento–San Joaquin Delta. But science and policymaking have been at odds about the roles of different stressors and the potential of various management actions to improve ecosystem health. In the summer of 2012, PPIC conducted two confidential surveys on the impact of ecosystem stressors: one sought input from scientific experts and the other focused on stakeholders and policymakers. This report analyzes the results and examines the implications of both surveys.

Scoping Report for Post-2026 Colorado River Reservoir Operations Upper and Lower Colorado Basin Regions

U.S. Bureau of Reclamation (USBR) | October 19th, 2023

This scoping summary was prepared to document the scoping process for the Post-2026 Colorado River Reservoir Operations (Post-2026 process). As several important reservoi

This scoping summary was prepared to document the scoping process for the Post-2026 Colorado River Reservoir Operations (Post-2026 process). As several important reservoir and water management decisional documents and agreements that govern operation of Colorado River facilities and management of Colorado River water are scheduled to expire at the end of 2026, the Post-2026 process has been initiated to develop successor domestic Colorado River operational guidelines and strategies for Lake Powell and Lake Mead.

Scott River Ajudication Decree

California State Water Resources Control Board (SWRCB) | January 30th, 1980

The water rights set forth in this decree consist of (1) all surface water rights in the Scott River stream system, as defined in paragraph 2, excluding springs or standi

The water rights set forth in this decree consist of (1) all surface water rights in the Scott River stream system, as defined in paragraph 2, excluding springs or standing pools not specifically included in this decree which do not contribute to a flowing stream or have no natural outlet, and excluding water which naturally sustains mountain meadows and other native vegetation without artificial diversion from a flowing stream; (2) all rights to supporting underflow and (3) all rights to ground water that i s interconnected with tlie Scott River as delineated on the State Water Resources Control Board map, hereinafter referred to as the SWRCB map, and as defined in Paragraph 4.

Scott Valley Community Groundwater Study Plan

University of California, Davis (UC Davis) | February 11th, 2008

This Scott Valley Groundwater Study Plan (GW Study Plan) has been requested of Siskiyou County and its Scott Valley stakeholders, as set forth in the Action Plan for the

This Scott Valley Groundwater Study Plan (GW Study Plan) has been requested of Siskiyou County and its Scott Valley stakeholders, as set forth in the Action Plan for the Scott River Temperature Total Maximum Daily Load (TMDL) (adopted Dec. 2005 by the California North Coast Regional Water Board [RWB]). The Action Plan sets forth the elements to be contained in this GW Study Plan; it also sets forth the needs of the RWB for certain information to be developed from the groundwater studies set forth in the GW Study Plan. It has been agreed by Siskiyou County and Regional Water Board staff that the hydrology of the entire valley needs to be understood in order to know the possible array of solutions to any water issues or problems in the Scott Valley. Siskiyou County with its management jurisdiction over groundwater (the RWB has water quality jurisdiction over groundwater under the Porter-Cologne Act) will take a community-based approach to groundwater management planning and to implementing this GW Study Plan. Data, information, and analysis are needed through studies to understand the groundwater hydrology of the Scott River system and its relationship to surface hydrology, especially in areas where groundwater could affect Scott River water temperatures, potential riparian vegetation, and habitat connectivity for anadromous fish. Without knowledge of the overall groundwater hydrology of Scott Valley, solutions to specific issues outlined in the TMDL Action Plan and the Scott River Watershed Council (SRWC) Strategic Action Plan will not be possible. It will be more cost effective to discover and prevent problems before they occur. Baseline data will be needed to determine the best approach in the design and implementation of water projects and water management alternatives and strategies to protect anadromous fish while also protecting the other beneficial uses, including the needs of agricultural operations. Much of this information will need to be developed over a period of time necessary to have a sufficient record from which to discover and test feasible and effective management strategies. This GW Study Plan was developed by the University of California at Davis (UC Davis) with the voluntary assistance of communities, landowners, the SRWC, and the Siskiyou Resource Conservation District (SRCD). The GW Study Plan is intended to be a living blueprint of the hydrologic, ecologic, water resource management, and agricultural management research needs and of the investigative approaches that can be taken to develop management practices that meet the mandate for protection of water, agricultural, and ecological resources in the Scott Valley. The GW Study Plan summarizes the current status of knowledge about the hydro-agro-eco-geography of the Scott Valley and outlines potential approaches to addressing critical current research needs. Individual study projects and tasks are described and scheduled in a way that is most efficient and timely to make the best use of funds to collect the information and data needed.

Scott Valley Groundwater Sustainability Plan

Siskiyou County Flood Control and Water Conservation District | January 20th, 2022

Due to file size, this document has been divided into multiple files. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9 Plan approved by DW

Due to file size, this document has been divided into multiple files. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9 Plan approved by DWR 4/27/23.

Scott Valley Integrated Hydrologic Model: Data Collection, Analysis, and Water Budget Final Report

University of California, Davis (UC Davis) | November 14th, 2017

The Scott Valley is an agricultural groundwater basin in Northern California, within the Scott River watershed and part of the much larger Klamath Basin watershed straddl

The Scott Valley is an agricultural groundwater basin in Northern California, within the Scott River watershed and part of the much larger Klamath Basin watershed straddling the California-Oregon border. The Scott River provides important habitat for salmonid fish, including spawning and rearing habitat for coho and fall-run Chinook salmon and steelhead trout. Sufficient flows at adequately low temperatures during summer, for rearing, and fall, for spawning, are critical for healthy fish habitat in the mainstem and tributaries. This report presents the data assembled and the methods used for data analysis and data modeling to prepare the Scott Valley Integrated Hydrologic Model Version 2, which is currently under development. The report includes precipitation data analysis, streamflow data analysis and modeling, geology and groundwater data review and analysis, evapotranspiration and soils data analysis, and preparation of relevant watershed, land use, topography, and irrigation data. The data collection and analysis efforts culminate in the development of a spatio-temporally distributed soil water budget model for the Scott Valley. The soil water budget model is used to determine spatially and temporally varying groundwater pumping rates, surface water diversion rates, and groundwater recharge across the groundwater basin. The spatial resolution of the soil water budget model is by individual fields (land use polygons). Temporal discretization is in daily time steps for the period from October 1, 1990 to September 30, 2011. This period includes several dry years, average years, and wet year periods. Methods and results of the soil water budget model are presented in this report. This report represents the next step toward a better understanding of the interactions between groundwater, surface water, land-use, and agricultural practices with a specific focus on the seasonal impacts of groundwater pumping on streamflow during critical low flow periods. The work presented here relies on an extensive data collection facilitated by the voluntary and active collaboration of communities, landowners, the Scott River Watershed Council (SRWC), the Siskiyou Resource Conservation District (SRCD), and the Scott Valley Groundwater Advisory Committee (GWAC) which has been appointed by the Board of Supervisors in January 2011, meeting monthly since April 2011 and advising UC Davis on its data collection and modeling efforts. In the data analysis and during the model development, numerous assumptions have been made as is common in building a conceptual and numerical integrated hydrologic model. Models cannot represent the complexity of the real system, but are an effort to capture salient hydrologic features with sufficient accuracy to develop modeling results that are useful for a better understanding of the watershed dynamics and water balance.

Screening of Pharmaceuticals in San Francisco Bay Wastewater

San Francisco Estuary Institute (SFEI) | October 1st, 2018

Previous studies have shown that pharmaceuticals are widely detected in San Francisco Bay, and some compounds occasionally approach levels of concern for wildlife. In 20

Previous studies have shown that pharmaceuticals are widely detected in San Francisco Bay, and some compounds occasionally approach levels of concern for wildlife. In 2016 and 2017, seven wastewater treatment facilities located throughout the Bay Area voluntarily collected wastewater samples and funded analyses for 104 pharmaceutical compounds. This dataset represents the most comprehensive analysis of pharmaceuticals in wastewater to date in this region. On behalf of the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP), the complete dataset was reviewed utilizing RMP quality assurance methods. An analysis of influent and effluent information is summarized in this report, and is intended to inform future monitoring recommendations for the Bay.

Scrutinizing the Delta Cross Channel

CALFED | June 1st, 2001

Sea level rise and flooding of hazardous sites in marginalized communities across the United States

Nature Portfolio (Springer Nature) | November 20th, 2025

Sea level rise (SLR) increases the risk of flooding at coastal sites that use and produce hazardous substances. We assess whether socially marginalized populations in the

Sea level rise (SLR) increases the risk of flooding at coastal sites that use and produce hazardous substances. We assess whether socially marginalized populations in the United States are more likely to be impacted by projected SLR-related flooding of hazardous sites that could result in contaminant releases. We identify 5500 facilities at risk of a 1-in-100-year flood event by 2100 under a scenario of continued high greenhouse gas emissions, including coastal power plants, sewage treatment facilities, fossil fuel infrastructure, industrial facilities, and formerly used defense sites. Seven states (Louisiana, Florida, New Jersey, Texas, California, New York, and Massachusetts) account for nearly 80% of projected at-risk facilities. Controlling for population density and county, a one standard deviation increase in the proportion of linguistically isolated households, neighborhood residents identifying as Hispanic, households with incomes below twice the federal poverty line, households without a vehicle, non-voters, and renters is associated with 19-41% higher likelihood of having a site at risk of SLR-related flooding within 1 kilometer (odds ratios [95% confidence intervals]: 1.19 [1.09, 1.31], 1.22 [1.08, 1.37], 1.27 [1.16, 1.39], 1.35 [1.21-1.51], 1.36 [1.21, 1.53], and 1.41 [1.32, 1.52], respectively). Results elucidate the need for disaster planning, land-use decision-making, as well as mitigation strategies that address the inequitable hazards and potential health threats posed by SLR.