CV-SALTS Prioritization & Optimization Study: Final Baseline Characterization Report

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | March 9th, 2024

The Central Valley Regional Water Quality Control Board (Central Valley Water Board) first adopted a three-phased Salt Control Program into the water quality regulations

The Central Valley Regional Water Quality Control Board (Central Valley Water Board) first adopted a three-phased Salt Control Program into the water quality regulations applicable to the Central Valley Region of California in 2018; these regulations were subsequently amended in 2020. Phase I of the Salt Control Program requires implementation of the Prioritization and Optimization (P&O) Study. The primary purposes of this Study are to characterize existing salinity conditions in surface water and groundwater in the Central Valley Region, establish appropriate salinity targets for the protection of beneficial uses, and facilitate the development of long-term salt management alternatives for implementation in Phases II and III of the Salt Control Program.

Cyanobacteria Assessment Network : pilot study with Sentinel-2–derived chlorophyll data

U.S. Army Corps of Engineers (USACE) | September 14th, 2026

Harmful algal blooms (HABs) affect global water quality, limiting uses like recreation and consumption because of excessive algal biomass and toxin production. These bloo

Harmful algal blooms (HABs) affect global water quality, limiting uses like recreation and consumption because of excessive algal biomass and toxin production. These blooms cause surface scums, taste and odor issues, hypoxia, and negative health and socioeconomic impacts. The US Army Corps of Engineers (USACE) manages over 400 lakes and reservoirs and seeks to improve monitoring of HABs through Sentinel-2 (S2) satellite imagery. The purpose of this project is to develop workflows for a national chlorophyll-a product with 20 m spatial resolution, enabling HAB monitoring for over 270,000 lakes and reservoirs. The 1-year pilot study established a federal partnership to conduct preliminary S2 processing steps, using datasets from Florida, Ohio, and Oregon. Key steps included in situ data aggregation, data assimilation, S2 algorithm evaluation, spatial and temporal compositing, satellite sensor cross-validation, and web hosting of an example prototype product. The study covers 29 USACE reservoirs, with cross-validation using Sentinel-3 (S3) data from 212 lakes. The multi-agency initiative aligns with federal agency missions to protect health and the environment, supports acts like the 2017 Harmful Algal Bloom and Hypoxia Research and Control Act, and has annual potential avoided costs of $42 million.

Daily stream samples reveal highly complex pesticide occurrence and potential toxicity to aquatic life

Science of the Total Environment (Elsevier) | May 1st, 2020

Transient, acutely toxic concentrations of pesticides in streams can go undetected by fixed-interval sampling programs. Here we compare temporal patterns in occurrence of

Transient, acutely toxic concentrations of pesticides in streams can go undetected by fixed-interval sampling programs. Here we compare temporal patterns in occurrence of current-use pesticides in daily composite samples to those in weekly composite and weekly discrete samples of surface water from 14 small stream sites. Samples were collected over 10–14 weeks at 7 stream sites in each of the Midwestern and Southeastern United States. Samples were analyzed for over 200 pesticides and degradates by direct aqueous injection liquid chromatography with tandem mass spectrometry. Nearly 2 and 3 times as many unique pesticides were detected in daily samples as in weekly composite and weekly discrete samples, respectively. Based on exceedances of acute-invertebrate benchmarks (AIB) and(or) a Pesticide Toxicity Index (PTI) >1, potential acute-invertebrate toxicity was predicted at 11 of 14 sites from the results for daily composite samples, but was predicted for only 3 sites from weekly composites and for no sites from weekly discrete samples. Insecticides were responsible for most of the potential invertebrate toxicity, occurred transiently, and frequently were missed by the weekly discrete and composite samples. The number of days with benthic-invertebrate PTI ≥0.1 in daily composite samples was inversely related to Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness at the sites. The results of the study indicate that short-term, potentially toxic peaks in pesticides frequently are missed by weekly discrete sampling, and that such peaks may contribute to degradation of invertebrate community condition in small streams. Weekly composite samples underestimated maximum concentrations and potential acute-invertebrate toxicity, but to a lesser degree than weekly discrete samples, and provided a reasonable approximation of the 90th percentile total concentrations of herbicides, insecticides, and fungicides, suggesting that weekly composite sampling may be a compromise between assessment needs and cost.

Data from a Thick Unsaturated Zone Underlying Oro Grande and Sheep Creek Washes in the Western Part of the Mojave Desert, near Victorville, San Bernardino County, California

U.S. Geological Survey (USGS) | January 1st, 2000

This report presents data collected as part of a cooperative study of infiltration and groundwater recharge to the regional aquifer near Victorville, California.

This report presents data collected as part of a cooperative study of infiltration and groundwater recharge to the regional aquifer near Victorville, California. The study was funded by the U.S. Geological Survey (USGS) and the Mojave Water Agency. This report contains data on drilling, instrument installation, the physical properties of unsaturated earth materials, and the chemical and isotopic composition of leachate from cores and cuttings, soil water, and soil gas collected at sites underlying Oro Grande and Sheep Creek Washes in the Mojave Desert. The report also presents similar data collected at sites on the alluvial fan near these washes and at a site near Cajon Pass. The sites on the alluvial fan and near Cajon Pass served as controls for the study and allow for comparison with data from previous studies. In addition, the report presents data on the chemical and isotopic composition of bulk precipitation, and on groundwater levels and quality. Interpretation of these data is beyond the scope of this report.

Data from Exploratory Sampling of Groundwater in Selected Oil and Gas Areas of Coastal Los Angeles County and Kern and Kings Counties in Southern San Joaquin Valley, 2014–15

U.S. Geological Survey (USGS) | December 9th, 2016

Exploratory sampling of groundwater in coastal Los Angeles County and Kern and Kings Counties of the southern San Joaquin Valley was done by the U.S. Geological Survey fr

Exploratory sampling of groundwater in coastal Los Angeles County and Kern and Kings Counties of the southern San Joaquin Valley was done by the U.S. Geological Survey from September 2014 through January 2015 as part of the California State Water Resources Control Board’s Water Quality in Areas of Oil and Gas Production Regional Groundwater Monitoring Program. The Regional Groundwater Monitoring Program was established in response to the California Senate Bill 4 of 2013 mandating that the California State Water Resources Control Board design and implement a groundwater-monitoring program to assess potential effects of well-stimulation treatments on groundwater resources in California. The U.S. Geological Survey is in cooperation with the California State Water Resources Control Board to collaboratively implement the Regional Groundwater Monitoring Program through the California Oil, Gas, and Groundwater Project. Many researchers have documented the utility of different suites of chemical tracers for evaluating the effects of oil and gas development on groundwater quality. The purpose of this exploratory sampling effort was to determine whether tracers reported in the literature could be used effectively in California. This reconnaissance effort was not designed to assess the effects of oil and gas on groundwater quality in the sampled areas. A suite of water-quality indicators and geochemical tracers were sampled at groundwater sites in selected areas that have extensive oil and gas development. Groundwater samples were collected from a total of 51 wells, including 37 monitoring wells at 17 multiple-well monitoring sites in coastal Los Angeles County and 5 monitoring wells and 9 water-production wells in southern San Joaquin Valley, primarily in Kern and Kings Counties. Groundwater samples were analyzed for field water-quality indicators; organic constituents, including volatile and semi-volatile organic compounds and dissolved organic carbon indicators; naturally present inorganic constituents, including trace elements, nutrients, major and minor ions, and iron species; naturally present stable and radioactive isotopes; dissolved noble gases; dissolved standard and hydrocarbon gases, ?13C of methane, ethane, and ?2H of methane. In total, 249 constituents and water-quality indicators were measured. Four types of quality-control samples (blanks, replicates, matrix spikes, and surrogates spiked in environmental and blank samples) were collected at approximately 10 percent of the wells. The quality-control data were used to determine whether the groundwater-sample data were of sufficient quality for the measured analytes to be used as potential indicators of oil and gas effects. The data from the 51 groundwater samples and from the quality-control samples are presented in this report.

Death Valley lower carbonate aquifer monitoring program—Wells down gradient of the proposed Yucca Mountain nuclear waste repository: U.S. Department of Energy Cooperative Agreement DE-FCO8-02RW12162 Final Project Report

Inyo County | July 1st, 2005

Decadal trends in the quality of groundwater used for public drinking-water supply in California, 2004–23

U.S. Geological Survey (USGS) | July 30th, 2026

This study provides a comprehensive assessment of decadal changes in the quality of groundwater used for public drinking- water supply at 444 monitoring sites across Cali

This study provides a comprehensive assessment of decadal changes in the quality of groundwater used for public drinking- water supply at 444 monitoring sites across California during 2004–23. We assessed decadal step trends in groundwater quality for 145 water- quality constituents and geochemical indicators statewide and across geographic and land- use based network groups. We evaluated the statistical significance of directional changes (predominant increase or decrease of constituent concentrations) and the magnitude of those changes across all network groups.

Delta Chromium-53/52 isotopic composition of native and contaminated groundwater, Mojave Desert, USA

Applied Geochemistry (Elsevier) | April 20th, 2012

Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, wer

Chromium(VI) concentrations in groundwater sampled from three contaminant plumes in aquifers in the Mojave Desert near Hinkley, Topock and El Mirage, California, USA, were as high as 2600, 5800 and 330 μg/L, respectively. δ53/52Cr compositions from more than 50 samples collected within these plumes ranged from near 0‰ to almost 4‰ near the plume margins. Assuming only reductive fractionation of Cr(VI) to Cr(III) within the plume, apparent fractionation factors for δ53/52Cr isotopes ranged from εapp = 0.3 to 0.4 within the Hinkley and Topock plumes, respectively, and only the El Mirage plume had a fractionation factor similar to the laboratory derived value of ε = 3.5. One possible explanation for the difference between field and laboratory fractionation factors at the Hinkley and Topock sites is localized reductive fractionation of Cr(VI) to Cr(III), with subsequent advective mixing of native and contaminated water near the plume margin. Chromium(VI) concentrations and δ53/52Cr isotopic compositions did not uniquely define the source of Cr near the plume margin, or the extent of reductive fractionation within the plume. However, Cr(VI) and δ53/52Cr data contribute to understanding of the interaction between reductive and mixing processes that occur within and near the margins of Cr contamination plumes. Reductive fractionation of Cr(VI) predominates in plumes having higher εapp, these plumes may be suitable for monitored natural attenuation. In contrast, advective mixing predominates in plumes having lower εapp, the highly dispersed margins of these plumes may be difficult to define and manage.

Delta Independent Science Board -- Comments on the Sacramento / Delta Draft Staff Report

Delta Stewardship Council (Delta Council) | January 19th, 2024

Delta Operations for Salmonids and Sturgeon (DOSS) Technical Working Group

Delta Stewardship Council (Delta Council) | November 1st, 2018