Regional Watershed Spreadsheet Model (RWSM) Year 5 Progress Report

San Francisco Estuary Institute (SFEI) | March 1st, 2016

The Regional Watershed Spreadsheet Model (RWSM) is a regional-scale planning tool developed primarily to estimate long-term average annual loads from the small tributari

The Regional Watershed Spreadsheet Model (RWSM) is a regional-scale planning tool developed primarily to estimate long-term average annual loads from the small tributaries surrounding San Francisco Bay, and secondarily to provide supporting information for prioritizing watersheds or areas within watersheds for management actions. The RWSM has been in development since 2010. In previous years, obstacles to calibrating the PCB and Hg models included issues associated with GIS data underlying the Model, a simplistic model structure and parameterization, lack of available empirical data for calibrating concentrations associated with specific land uses and source areas, and the high uncertainty with the empirical calibration dataset. The modeling effort in Years 2014 and 2015 (Year 4 and 5 of the model development) focused on improving the model calibration to attempt to resolve these issues. The major changes included switching from a sediment-based model to a water-based model, elimination of double counting of source areas on top of general land uses, changes in the model calibration approach, and changes to the land use grouping.

Regulatory steps needed to protect and conserve wetlands not subject to the Clean Water Act

California State Water Resources Control Board (SWRCB) | November 17th, 2003

This report responds to legislative direction to describe the steps and resources needed to protect California wetlands and other waters that are not covered by the feder

This report responds to legislative direction to describe the steps and resources needed to protect California wetlands and other waters that are not covered by the federal Clean Water Act (CWA). It gives special attention to "isolated" waters removed from CWA jurisdiction by the U.S. Supreme Court's 2001 decision in Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (SWANCC). Wetlands and riparian areas support extraordinary biodiversity and are uniquely important in sustaining the hydrologic, chemical, and ecological integrity of broader aquatic systems. However, for physical and legal reasons, they present special management challenges. Neither CWA nor the state Porter-Cologne Water Quality Control Act (Porter-Cologne) were designed to conserve wetlands, and their regulatory protection is therefore often problematic and incomplete.

Relationship between wetland condition, stress, and buffer

San Francisco Estuary Institute (SFEI) | April 25th, 2016

Relationship between wetland size and CRAM condition scores for depressional wetlands

San Francisco Estuary Institute (SFEI) | March 28th, 2016

Relative risk of groundwater-quality degradation near California (USA) oil fields estimated from 3H, 14C, and 4He

Applied Geochemistry (Elsevier) | June 5th, 2021

 Relative risks of groundwater-quality degradation near selected California oil fields are estimated by examining spatial and temporal patterns in chemical and isotopic

 Relative risks of groundwater-quality degradation near selected California oil fields are estimated by examining spatial and temporal patterns in chemical and isotopic data in the context of groundwater-age categories defined by tritium and carbon-14. In the Coastal basins, western San Joaquin Valley (SJV), and eastern SJV; 82, 76, and 0% of samples are premodern (pre-1953 recharge), respectively; and 3, 0, and 31% are modern (recharged during or after 1953), respectively. Carbon-14 and helium-4 data indicate most premodern samples are 1000 to 10,000 (33%) or >10,000 (50%) years old. Organic chemicals that could be associated with deeper hydrocarbon reservoirs (e.g. thermogenic gases and benzene) occur most frequently in premodern groundwater, suggesting premodern groundwater has a higher risk of degradation from upward migration of hydrocarbons than modern and mixed-age groundwater. Low sulfate concentrations in some premodern groundwater containing high thermogenic-methane concentrations (>28 mg/L) indicate methane attenuation associated with sulfate reduction can be limited in premodern groundwater. The more common occurrence of manufactured compounds, like tetrachloroethene, in modern and mixed-age groundwater than in premodern groundwater indicates modern and mixed-age groundwater has a higher risk of degradation from land-surface sources than premodern groundwater. Time-series data for chloride in groundwater affected by disposal of oil-field water in unlined ponds indicate some modern and mixed-age groundwater are susceptible to chemical migration within 2–3 km of surface sources. Timescales for diluting chloride concentrations in groundwater with fresh recharge once disposal ponds are decommissioned are shorter in mixed-age groundwater with large fractions of modern water (9–14 years in one example) than in mixed-age groundwater with large fractions of premodern water (no evidence of dilution after 12 years of monitoring in one example). The presence of predominantly premodern groundwater in the Coastal basins and western SJV indicates these areas have relatively high risk from upward migration of hydrocarbons, reduced methane attenuation capacity, and long dilution times, whereas predominantly modern-and mixed-age groundwater in the eastern SJV indicates this area has relatively high risk from chemical migration from land-surface sources and subsequent extensive spreading. Age-based characterizations of relative risk could inform the design of groundwater-monitoring programs near oil fields in terms of the spatial distribution of monitoring points relative to source areas and monitoring frequency and duration. 

Remedial Investigation Report for Former Titan 1-A Missile Facility, Lincoln, California

U.S. Army Corps of Engineers (USACE) | February 12th, 2025

Previous investigations have identified groundwater and soil vapor as the primary environmental matrices that have been impacted by the release and volatile organic compo

Previous investigations have identified groundwater and soil vapor as the primary environmental matrices that have been impacted by the release and volatile organic compounds (VOCs) as the contaminants of potential concern (COPCs). Previous investigations have determined that the DOD-related releases at the Site consist of benzene, toluene, ethylbenzene, xylenes (BTEX), trichloroethene (TCE), and TCE’s degradation products. The release has primarily impacted shallow groundwater and there does not appear to be a significant vadose zone (soil) source (Brown and Caldwell 2007a). This RI presents and evaluates previously collected data. No new data are provided in this report. Due to size, this document has been divided. Part one, Part two, Part three, Part four, Part five, Part six, Part seven Click here for proposed  USACE site remediation schedule

Remote sensing is a viable tool for mapping soil salinity in agricultural lands

University of California, Davis (UC Davis) | April 7th, 2017

Report of Waste Discharge and Technical Report

Westlands Water District | July 10th, 2019

This Technical Report is in support of a Report of Waste Discharge (ROWD) for an agricultural aquifer storage and recovery (Ag-ASR) program for Westlands Water District

This Technical Report is in support of a Report of Waste Discharge (ROWD) for an agricultural aquifer storage and recovery (Ag-ASR) program for Westlands Water District (Westlands or District). The District is located in western Fresno and Kings Counties in the San Joaquin Valley. With the new Sustainable Groundwater Management Act (SGMA) signed into law in 2014, Westlands is pursuing means to recharge groundwater within the District’s boundaries, which coincide with the Westside Subbasin (Groundwater Subbasin Number 5-22.09). Due to the presence of poor quality shallow groundwater, fine-grained soils, and the Corcoran Clay restrictive layer, surface recharge opportunities are limited (Schmidt, 2009). Direct injection using Ag-ASR wells holds promise as a more widely implementable recharge method in the District.

Report on Salton Sea Projects

California Natural Resources Agency (CNRA) | April 8th, 2016

Formed in 1905 when Colorado River flood waters breached an irrigation diversion structure and caused the river to temporarily flow into the then-dry Salton Sink, today�

Formed in 1905 when Colorado River flood waters breached an irrigation diversion structure and caused the river to temporarily flow into the then-dry Salton Sink, today’s Salton Sea is only the latest in a long succession of waterbodies to occupy the area. At 350 square miles, California’s largest lake is hydrologically connected to the Colorado River system and has been largely maintained since the 1905 event by irrigation water from agricultural production in the Imperial Valley. The historic Quantification Settlement Agreement (2003) provided California the means to implement water transfers and supply programs that allowed the state to live within its 4.4 million acre-foot basic annual apportionment of Colorado River water. Though long plagued by problems associated with its terminality—and resultant accumulation of salts, nutrients, and other impurities—the water transfers contained in the QSA meant a hastening of its ecological decline. Mitigation waters were provided for the Sea in the agreement, but are set to expire in 2017.  In response to growing concern about the impending and current deterioration of conditions at the Salton Sea, California Governor Edmund G. Brown Jr. in May 2015 created the Salton Sea Task Force to rapidly evaluate and take action to bring certainty to the Sea’s future and develop a series of findings that would guide further action at the lake. To coordinate and facilitate the actions the Governor also created the position of Assistant Secretary for Salton Sea Policy within the California Natural Resources Agency (CNRA).  The Salton Sea Task Force issued their findings in November 2015, which called for the development of a Salton Sea Management Program that covered three major elements: sustainable habitat; air quality and potential private sector energy development. The Task Force also acknowledged that a successful program depends on the following three principles: 1) strong state, federal, and local partnerships; 2) clear and achievable milestones with state directed plans to achieve them; and 3) committed participation from all stakeholders who share the goals of protecting air quality, reducing habitat impacts, and maintaining a secure Colorado River Water Supply. Task Force findings also contained a series of actions for implementation by the California Natural Resources Agency (CNRA) that included the development of a Salton Sea Management Plan with short and midterm goals for habitat and dust suppression projects, an improved public awareness and local partnerships program and an accelerated implementation of planning, permitting and construction. 

Resilient Landscape Vision for the Calabazas Creek, San Tomas Aquino Creek, and Pond A8 Area: Bayland-Creek Reconnection Opportunities

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

This report proposes a multi-faceted redesign of the South San Francisco Bay shoreline at the interface with Calabazas and San Tomas Aquino creeks. Recognizing the opport

This report proposes a multi-faceted redesign of the South San Francisco Bay shoreline at the interface with Calabazas and San Tomas Aquino creeks. Recognizing the opportunities presented by changing land use and new challenges, such as accelerated sea-level rise, we explore in this report a reconfigured shoreline that could improve ecosystem health and resilience, reduce maintenance costs, and protect surrounding infrastructure.