Delta Conveyance Project Final Environmental Impact Report

California Department of Water Resources (DWR) | December 8th, 2023

Delta Levee Investment Strategy: Final Report

Delta Stewardship Council (Delta Council) | August 4th, 2017

In the California Sacramento-San Joaquin Delta (Delta), levee failure could cause catastrophic flooding, potentially causing injury or loss of life, and possibly damaging

In the California Sacramento-San Joaquin Delta (Delta), levee failure could cause catastrophic flooding, potentially causing injury or loss of life, and possibly damaging property, water supply, infrastructure, and environmental resources of importance to the entire State of California (State). Though levee maintenance and improvements over the past three decades have reduced the frequency of levee failures, the State has no comprehensive method to prioritize its investments in Delta levees operations, maintenance, and improvement projects. The Delta Plan, adopted on May 16, 2013, recommends that the Delta Stewardship Council (Council), in consultation with the California Department of Water Resources (DWR), the Central Valley Flood Protection Board (CVFPB), the Delta Protection Commission (DPC), local agencies, and the California Water Commission, implement California Water Code (CWC) section 85306 by developing a Delta Levees Investment Strategy (DLIS) to identify funding priorities for State investments in Delta levees. The DLIS is an innovative approach for determining priorities for State funds for levee improvement in the Delta and Suisun Marsh. The DLIS, which considers the assets protected by levees, the threats to levees, and the multiple beneficiaries of levee investments, uses a risk analysis methodology to recommend priorities for State investments in levee operations, maintenance, and improvements. This methodology was developed in close coordination with State agency partners, local and regional flood management and emergency response planning agencies, and other interested parties. In total, the Council worked with 113 different stakeholders and conducted 10 public meetings, 60 stakeholder outreach meetings, and 60 interagency coordination meetings. The Council also discussed DLIS issues at 38 Council meetings and workshops, which provided opportunities for public comment. The DLIS team developed a Decision Support Tool (DST) to enable the Council and stakeholders to review and update the data and analysis that form the basis of the risk evaluation. The DST supports deliberations by summarizing information about baseline and future risks, aggregating and displaying risks, and then identifying portfolios of investments that have the potential to reduce risk to State interests. The data components in the DST are designed to be updated as new information is collected or identified.

Delta Regional Monitoring Program Annual Monitoring Report for Fiscal Year 2015–16: Pesticides and Toxicity

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

The primary purpose of this report is to document the first year (FY15/16) of pesticide monitoring by the Delta Regional Monitoring Program (Delta RMP). This document rep

The primary purpose of this report is to document the first year (FY15/16) of pesticide monitoring by the Delta Regional Monitoring Program (Delta RMP). This document reports the results from samples collected monthly from July 2015 through June 2016. The data described in this report are available for download via the California Environmental Data Exchange Network (CEDEN) website. Pesticide monitoring of the Delta RMP includes chemical analysis and toxicity testing of surface water samples. The parameters analyzed include 154 current use pesticides, dissolved copper, field parameters, and “conventional” parameters (ancillary parameters measured in the laboratory, such as dissolved/particulate organic carbon and hardness). Toxicity tests included an algal species (Selenastrum capricornutum, also known as Raphidocelis subcapitata), an invertebrate (Ceriodaphnia dubia, a daphnid or water flea), and a fish species (Pimephales promelas, fathead minnow). Toxicity testing included the evaluation of acute (survival) and chronic (growth, reproduction, biomass) toxicity endpoints. The surface water samples were collected from 5 fixed sites representing key inflows to the Delta that were visited monthly: Mokelumne River at New Hope Road, Sacramento River at Hood, San Joaquin River at Buckley Cove, San Joaquin River at Vernalis, and Ulatis Creek at Brown Road. A total of 52 pesticides were detected above method detection limits (MDLs) in water samples (19 fungicides, 17 herbicides, 9 insecticides, 6 degradates, and 1 synergist). A total of 9 pesticides (5 herbicides, 3 insecticides, and 1 degradate) were detected in suspended sediments in 10 of a total of 60 samples collected during the study period. All collected samples contained mixtures of pesticides ranging from 2 to 26 pesticides per sample. From a total of 154 target parameters, 100 compounds were never detected in any of the samples.

Delta Regional Monitoring Program Nutrients Synthesis: Modeling to Assist Identification of Temporal and Spatial Data Gaps for Nutrient Monitoring

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

Nutrient loads are an important water quality management issue in the Sacramento-San Joaquin Delta (Delta) and there is consensus that the current monitoring activities d

Nutrient loads are an important water quality management issue in the Sacramento-San Joaquin Delta (Delta) and there is consensus that the current monitoring activities do not collect all the information needed to answer important management questions.  The purpose of this report is to use hydrodynamic model outputs to refine recommendations for monitoring nutrients and related conditions in the Delta. The basic premise was that variability in water source and hydraulic residence time can serve to estimate variability in water quality. Therefore, using existing hydrodynamic models that are highly resolved in space and time could be a cost-effective way to get information about likely spatial and temporal variability in nutrients and nutrient-associated parameters. We assume that the Delta can be divided into relatively homogeneous subregions (e.g., such as those proposed in a previous report by Jabusch et al. 2016) and that a representative monitoring location can be chosen in each subregion to track status and trends. We also assume that, within any subregion, areas with long hydraulic residence time and source water mixing may represent potential nutrient transformation hotspots.  Two types of modeling approaches were applied: 1) volumetric water source analysis to evaluate the mix of source waters within each subregion; and 2) particle tracking simulations. Results from the source water analysis were evaluated to assess heterogeneity of water sources within each of the subregions. Results from the particle tracking analysis were evaluated to identify high-residence-time areas. Finally, we compared analysis results to current monitoring locations to inform potential monitoring gaps or redundancies within each of the subregions. 

Delta Salinity Management Workshops 2022 Information Sheet

Delta Stewardship Council (Delta Council) | March 7th, 2022

Delta Subsidence in California: The sinking heart of the state

U.S. Geological Survey (USGS) | April 8th, 2000

The Sacramento-San Joaquin River Delta of California once was a great tidal freshwater marsh blanketed by peat and peaty alluvium. Beginning in the late 1800s, levees wer

The Sacramento-San Joaquin River Delta of California once was a great tidal freshwater marsh blanketed by peat and peaty alluvium. Beginning in the late 1800s, levees were built along the stream channels, and the land thus protected from flooding was drained, cleared, and planted. Although the Delta is now an exceptionally rich agricultural area (over a $500 million crop value in 1993), its unique value is as a source of freshwater for the rest of the State. It is the heart of a massive north-to-south water delivery system. Much of this water is pumped southward for use in the San Joaquin Valley and elsewhere in central and southern California. The leveed tracts and islands help to protect water-export facilities in the southern Delta from saltwater intrusion by displacing water and maintaining favorable freshwater gradients. However, ongoing subsidence behind the levees reduces levee stability and, thus, threatens to degrade water quality in the massive north-to-south water-transfer system.

Delta Vision Strategic Plan

State of California | October 17th, 2008

When it was created by Governor Schwarzenegger’s Executive Order S-17-06 in 2006, the charge of the Delta Vision Blue Ribbon Task Force (Task Force) was nothing less th

When it was created by Governor Schwarzenegger’s Executive Order S-17-06 in 2006, the charge of the Delta Vision Blue Ribbon Task Force (Task Force) was nothing less than to create a vision to repair the ecological damage to the Sacramento-San Joaquin River Delta (Delta), and then prepare a strategic plan which would sustain the Delta in future decades while ensuring a reliable water supply for the two-thirds of California’s population who depend in whole or in part on water from the Delta.

Delta Vision Strategic Plan -- from Phil Isenberg, 1939-2023

State of California | October 17th, 2008

When it was created by Governor Schwarzenegger’s Executive Order S-17-06 in 2006, the charge of the Delta Vision Blue Ribbon Task Force (Task Force) was nothing less th

When it was created by Governor Schwarzenegger’s Executive Order S-17-06 in 2006, the charge of the Delta Vision Blue Ribbon Task Force (Task Force) was nothing less than to create a vision to repair the ecological damage to the Sacramento-San Joaquin River Delta (Delta), and then prepare a strategic plan which would sustain the Delta in future decades while ensuring a reliable water supply for the two-thirds of California’s population who depend in whole or in part on water from the Delta.

Delta-Mendota Subbasin Staff Assessment

California State Water Resources Control Board (SWRCB) | March 2nd, 2026

The Delta-Mendota Subbasin (subbasin) is located in the western portion of the San Joaquin Valley, in portions of Fresno, Madera, Merced, San Joaquin, San Benito, and Sta

The Delta-Mendota Subbasin (subbasin) is located in the western portion of the San Joaquin Valley, in portions of Fresno, Madera, Merced, San Joaquin, San Benito, and Stanislaus counties, and contains the cities of Dos Palos, Firebaugh, Gustine, Los Banos, Mendota, Newman, and Patterson. It is critically overdrafted and managed by 7 GSA Groups, comprised of 23 GSAs, which include: the Aliso Water District GSA Group, the Farmers Water District GSA Group, the Fresno County Management Areas A and B GSA Group, the Grassland GSA Group, the Northern Delta-Mendota GSA Group, the Central Delta-Mendota GSA Group, and the San Joaquin River Exchange Contractors GSA Group. During most years, agriculture accounts for more than 85% of groundwater use in the subbasin (Water Year 2019–Water Year 2024 Annual Reports). The state intervention process for the Delta-Mendota Subbasin was initiated in March 2023 when DWR determined the subbasin’s six 2022 GSPs were inadequate.  The GSAs released a single revised draft GSP in May 2024, which they adopted with slight revisions in July 2024 (2024 GSP). State Water Board staff evaluated the 2024 GSP to determine if identified deficiencies were resolved. The GSAs made significant progress. State Water Board staff concludes the GSAs amended the GSP such that a probationary designation of the Delta-Mendota Subbasin is unnecessary and recommends the Board return the subbasin to DWR’s jurisdiction for continued evaluation of local management under SGMA.

Demographic predictors of urinary arsenic in a low-income predominantly Hispanic pregnancy cohort in Los Angeles

Journal of Exposure Science & Environmental Epidemiology (Springer) | July 27th, 2020

Arsenic (As) is a contaminant of top public health concern, due to its range of detrimental health effects. Arsenic exposure has not been well-characterized among the US

Arsenic (As) is a contaminant of top public health concern, due to its range of detrimental health effects. Arsenic exposure has not been well-characterized among the US Hispanic populations and has been particularly understudied in this population during pregnancy. As part of the MADRES ongoing pregnancy cohort of predominantly lower-income, Hispanic women in Los Angeles, CA, we examined levels of maternal first trimester urinary As, including total As and As metabolites (inorganic (iAs), monomethylated (MMA) and dimethylated As (DMA)), in relation to participant demographics, lifestyle characteristics, and rice/seafood consumption, to identify factors that may influence As exposure and its metabolites during pregnancy (N = 241). Total As concentrations ranged from low to high (0.8–506.2 μg/L, mean: 9.0 μg/L, SD: 32.9) in our study population. Foreign-born Hispanic women had 8.6% higher %DMA (95% CI: 3.3%, 13.9%) and −7.7% lower %iAs (95% CI: −12.6%, −2.9%) than non-Hispanic women. A similar trend was observed for US-born Hispanic women. In addition, maternal age was associated with 0.4% higher %iAs (95% CI: 0.1%, 0.6%) and 0.4% lower %DMA (95% CI: −0.7%, −0.1%) per year, which may indicate poor As methylation capacity. Individual factors may predict As exposure and metabolism in pregnancy, and in turn, greater risk of adverse health effects.