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Status and Understanding of Groundwater Quality in the Sierra Nevada Regional Study Unit, 2008: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | December 23rd, 2014

Summary

Groundwater quality in the Sierra Nevada Regional (SNR) study unit was investigated as part of the California State Water Resources Control Board’s Groundwater Ambient

Groundwater quality in the Sierra Nevada Regional (SNR) study unit was investigated as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment Program Priority Basin Project. The study was designed to provide statistically unbiased assessments of the quality of untreated groundwater within the primary aquifer system of the Sierra Nevada. The primary aquifer system for the SNR study unit was delineated by the depth intervals over which wells in the State of California’s database of public drinking-water supply wells are open or screened. Two types of assessments were made: (1) a status assessment that described the current quality of the groundwater resource, and (2) an evaluation of relations between groundwater quality and potential explanatory factors that represent characteristics of the primary aquifer system. The assessments characterize untreated groundwater quality, rather than the quality of treated drinking water delivered to consumers by water distributors. The status assessment was based on water-quality data collected by the U.S. Geological Survey from 83 wells in the SNR study unit in 2008 and from 117 wells in 3 small study units within the SNR study unit in 2006–07 and on water-quality data compiled in the State’s database for 1,066 wells sampled in 2006–08. To provide some context for the results, water-quality data were converted to relative-concentrations (RCs), which are the sample concentrations divided by the concentrations of Federal or California regulatory and non-regulatory benchmarks for drinking-water quality. RCs for inorganic constituents (major ions, trace elements, nutrients, and radioactive constituents) were classified as “high” (RC > 1.0, indicating that concentration is above the benchmark), “moderate” (1.0 ? RC > 0.5), or “low” (RC ? 0.5). For organic constituents (volatile organic compounds and pesticides) and special-interest constituents (perchlorate and N-nitrosodimethylamine [NDMA]), the boundary between moderate and low RCs was set at 0.1. All benchmarks used for organic constituents were health-based, whereas health-based and aesthetic-based benchmarks were used for inorganic constituents. The primary metric used for quantifying regional-scale groundwater quality was “aquifer-scale proportion.” Aquifer-scale proportions were calculated as the areal percentages of the primary aquifer system having high, moderate, and low RCs for a given constituent or class of constituents. The SNR study unit area was classified into four aquifer lithologic types—granitic rocks, metamorphic rocks, sedimentary deposits, and volcanic rocks—and aquifer-scale proportions were calculated on an area-weighted basis for each of the four aquifer lithologies and for the study unit as a whole (aggregated system).

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Status and Understanding of Groundwater Quality in the South Coast Interior Groundwater Basins, 2008: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | May 14th, 2014

Summary

Groundwater quality in the approximately 653-square-mile (1,691-square-kilometer) South Coast Interior Basins (SCI) study unit was investigated as part of the Priority Ba

Groundwater quality in the approximately 653-square-mile (1,691-square-kilometer) South Coast Interior Basins (SCI) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The South Coast Interior Basins study unit contains eight priority groundwater basins grouped into three study areas, Livermore, Gilroy, and Cuyama, in the Southern Coast Ranges hydrogeologic province. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA South Coast Interior Basins study was designed to provide a spatially unbiased assessment of untreated (raw) groundwater quality within the primary aquifer system, as well as a statistically consistent basis for comparing water quality between basins. The assessment was based on water-quality and ancillary data collected by the USGS from 50 wells in 2008 and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system was defined by the depth intervals of the wells listed in the CDPH database for the SCI study unit. The quality of groundwater in the primary aquifer system may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. The first component of this study, the status of the current quality of the groundwater resource, was assessed by using data from samples analyzed for volatile organic compounds (VOCs), pesticides, and naturally occurring inorganic constituents, such as trace elements and minor ions. This status assessment is intended to characterize the quality of groundwater resources within the primary aquifer system of the SCI study unit, not the treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentration divided by the health- or aesthetic-based benchmark concentration) were used for evaluating groundwater quality for those constituents that have Federal or California regulatory or non-regulatory benchmarks for drinking-water quality. A relative-concentration greater than 1.0 indicates a concentration greater than a benchmark, and a relative-concentration less than or equal to 1.0 indicates a concentration equal to or less than a benchmark. Relative-concentrations of organic constituents and special-interest constituents were classified as “high” (relative-concentration greater than 1.0), “moderate” (relative-concentration greater than 0.1 and less than or equal to 1.0), or “low” (relative-concentration less than or equal to 0.1). Relative-concentrations of inorganic constituents were classified as “high” (relative-concentration greater than 1.0), “moderate” (relative-concentration greater than 0.5 and less than or equal to 1.0), or “low” (relative-concentration less than or equal to 0.5). Aquifer-scale proportion was used as the primary metric in the status assessment for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the percentage of the area of the primary aquifer system with a relative-concentration greater than 1.0 for a particular constituent or class of constituents; percentage is based on an areal rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the areal percentage of the primary aquifer system with moderate and low relative-concentrations, respectively. Two statistical approaches—grid-based and spatially weighted—were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. Grid-based and spatially weighted estimates were comparable in the SCI study unit (within 90-percent confidence intervals). Inorganic constituents (one or more) with health-based benchmarks were detected at high relative-concentrations in 29 percent of the primary aquifer system, at moderate relative-concentrations in 37 percent, and at low relative-concentrations in 34 percent. High aquifer-scale proportions of inorganic constituents primarily reflected high aquifer-scale proportions of nitrate (14 percent), boron (8.6 percent), molybdenum (8.6 percent), and arsenic (5.7 percent). In contrast, the relative-concentrations of organic constituents (one or more) were high in 1.6 percent, moderate in 2.0 percent, and low or not detected in 96 percent of the primary aquifer system. Of the 207 organic and special-interest constituents analyzed for, 15 constituents were detected. Perchlorate was found at moderate relative-concentrations in 34 percent of the aquifer. Two organic constituents were frequently detected (in greater than 10 percent of samples): the trihalomethane chloroform and the herbicide simazine. The second component of this study, the understanding assessment, identified natural and human factors that may have affected groundwater quality by evaluating land use, physical characteristics of the wells, and geochemical conditions of the aquifer. This evaluation was done by using statistical tests of correlations between these potential explanatory factors and water-quality data. Concentrations of arsenic, molybdenum, and manganese were generally greater in anoxic and pre-modern groundwater than other groundwater. In contrast, concentrations of nitrate and perchlorate were significantly higher in oxic and modern groundwater. Concentrations of simazine were greater in modern than pre-modern groundwater. Chloroform detections were positively correlated with greater urban land use. Boron concentrations and chloroform detections were higher in the Livermore study area than in the other study areas of the SCI; total dissolved solids and sulfate concentrations were greater in the Cuyama study area.

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Status of California's Wadeable Perennial Streams (2000-2007)

California State Water Resources Control Board (SWRCB) | October 1st, 2011

Summary

The Surface Water Ambient Monitoring Program’s (SWAMP) Perennial Streams Assessment (PSA) surveys measure the ability of California’s perennial wadeable str

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Status of Groundwater Quality in the California Desert Region, 2006–2008: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | January 9th, 2013

Summary

Groundwater quality in six areas in the California Desert Region (Owens, Antelope, Mojave, Coachella, Colorado River, and Indian Wells) was investigated as part

Groundwater quality in six areas in the California Desert Region (Owens, Antelope, Mojave, Coachella, Colorado River, and Indian Wells) was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The six Desert studies were designed to provide a spatially unbiased assessment of the quality of untreated groundwater in parts of the Desert and the Basin and Range hydrogeologic provinces, as well as a statistically consistent basis for comparing groundwater quality to other areas in California and across the Nation. Samples were collected by the USGS from September 2006 through April 2008 from 253 wells in Imperial, Inyo, Kern, Los Angeles, Mono, Riverside, and San Bernardino Counties. Two-hundred wells were selected using a spatially distributed, randomized grid-based method to provide a spatially unbiased representation of the study areas (grid wells), and ffty-three wells were sampled to provide additional insight into groundwater conditions (additional wells). The status of the current quality of the groundwater resource was assessed based on data from samples analyzed for volatile organic compounds (VOCs), pesticides, and inorganic constituents such as major ions and trace elements. Water-quality data from the California Department of Public Health (CDPH) database also were incorporated in the assessment. The status assessment is intended to characterize the quality of untreated groundwater resources within the primary aquifer systems of the Desert Region, not the treated drinking water delivered to consumers by water purveyors. The primary aquifer systems (hereinafter, primary aquifers) in the six Desert areas are defined as that part of the aquifer corresponding to the perforation intervals of wells listed in the CDPH database.

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Status of Groundwater Quality in the Santa Barbara Study Unit, 2011: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | September 30th, 2016

Summary

Groundwater quality in the 48-square-mile Santa Barbara study unit was investigated in 2011 as part of the California State Water Resources Control Board’s Groundwater

Groundwater quality in the 48-square-mile Santa Barbara study unit was investigated in 2011 as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project. The study unit is mostly in Santa Barbara County and is in the Transverse and Selected Peninsular Ranges hydrogeologic province. The GAMA Priority Basin Project is carried out by the U.S. Geological Survey in collaboration with the California State Water Resources Control Board and Lawrence Livermore National Laboratory. The GAMA Priority Basin Project was designed to provide a statistically unbiased, spatially distributed assessment of the quality of untreated groundwater in the primary aquifer system of California. The primary aquifer system is defined as that part of the aquifer corresponding to the perforation interval of wells listed in the California Department of Public Health database for the Santa Barbara study unit. This status assessment is intended to characterize the quality of groundwater resources in the primary aquifer system of the Santa Barbara study unit, not the treated drinking water delivered to consumers by water purveyors. The status assessment for the Santa Barbara study unit was based on water-quality and ancillary data collected in 2011 by the U.S. Geological Survey from 23 sites and on water-quality data from the California Department of Public Health database for January 24, 2008–January 23, 2011. The data used for the assessment included volatile organic compounds; pesticides; pharmaceutical compounds; two constituents of special interest, perchlorate and N-nitrosodimethylamine (NDMA); and naturally present inorganic constituents, such as major ions and trace elements. Relative-concentrations (sample concentration divided by the health- or aesthetic-based benchmark concentration) were used to evaluate groundwater quality for those constituents that have federal or California regulatory and non-regulatory benchmarks for drinking-water quality. For inorganic, organic, and special-interest constituents, a relative-concentration greater than 1.0 indicates a concentration greater than the benchmark and is classified as high. Inorganic constituents are classified as moderate if relative-concentrations are greater than 0.5 and less than or equal to 1.0 and are classified as low if relative-concentrations are less than or equal to 0.5. For organic and special-interest constituents, the boundary between moderate and low relative-concentrations was set at 0.1. Aquifer-scale proportion was used as the primary metric for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the areal percentage of the primary aquifer system with a relative-concentration greater than 1.0 for a particular constituent or class of constituents. Moderate and low aquifer-scale proportions were defined as the areal percentage of the primary aquifer system that had moderate and low relative-concentrations, respectively. Two statistical approaches—grid based and spatially weighted—were used to calculate aquifer-scale proportions for individual constituents and constituent classes. Grid-based and spatially weighted estimates were comparable in this the study (within 90-percent confidence intervals). Grid-based results were selected for use in the status assessment unless, as was observed in a few cases, a grid-based result was zero and the spatially weighted result was not zero, in which case, the spatially weighted result was used. Inorganic constituents that have human-health benchmarks were present at high relative-concentrations in 5.3 percent of the primary aquifer system and at moderate concentrations in 32 percent. High aquifer-scale proportions of inorganic constituents primarily were a result of high aquifer-scale proportions of boron (5.3 percent) and fluoride (5.3 percent). Inorganic constituents that have aesthetic-based benchmarks, referred to as secondary maximum contaminant levels, were present at high relative-concentrations in 58 percent of the primary aquifer system and at moderate concentrations in 37 percent. Iron, manganese, sulfate, and total dissolved solids were the inorganic constituents with secondary maximum contaminant levels present at high relative-concentrations.

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Status of Perennial Estuarine Wetlands in the State of California

California State Water Resources Control Board (SWRCB) | November 1st, 2008

Summary

Section 305(b) of the Federal Clean Water Act (CWA) requires each state submit biennial reports describing the health of its surface water, including wetlands, to the USE

Section 305(b) of the Federal Clean Water Act (CWA) requires each state submit biennial reports describing the health of its surface water, including wetlands, to the USEPA. This document reports on the health of California’s perennial, saline estuarine wetlands. Estuaries are partially enclosed bodies of water along the coast where freshwater runoff meets and mixes with salt water from the ocean. Based on the draft definition of wetlands for California, an estuarine wetland is an area within an estuary that is exposed at low tide and covered with rooted vegetation. The health of the state’s estuarine wetlands is estimated from a statewide survey of the distribution, abundance, and ambient condition of estuarine wetlands. The survey had three components: 1) landscape profile; 2) probability-based assessment of ambient condition; and 3) assessment of selected estuarine wetland restoration and mitigation projects. The results help answer four fundamental management questions: 1) where are the State’s estuarine wetlands and how abundant are they; 2) what is the ambient condition of estuarine wetlands statewide and how does their condition vary by region; 3) what are the major stressors and how do they vary among coastal regions; and 4) what is the condition of permitted restoration projects relative to ambient condition. This fourth question demonstrates how data could be used to evaluate policies and programs affecting the distribution, abundance, and condition of estuarine wetlands. The landscape profile described the distribution and abundance of the State’s estuarine wetlands relative to other estuarine habitats and explored the underlying causes through a detailed examination of trends in San Francisco Estuary. A probability-based survey was used to assess the ambient condition of saline, perennial estuarine wetlands. The statewide ambient survey involved 120 sites allocated equally among four regions: North Coast, San Francisco Estuary, Central Coast, and South Coast. An additional 30 sites were allocated to South Coast to test for a difference between large and small estuaries. The field survey was conducted in the Fall of 2007. The statewide ambient survey in turn served as a regional frame of reference for project assessments. Both the ambient survey and the project assessments utilized the California Rapid Assessment Method (CRAM; Version 5.0.2). CRAM is a field-based method to assess wetland condition based on visible indicators of four wetland attributes: Landscape Context, Hydrology, Physical Structure, and Biological Structure. Results were reported as the percent of the total area of estuarine wetland in California likely to fall within four categories equally-spaced categories of possible CRAM index or attribute scores, which range from 25-100: Scores greater than 82 = Category 1; scores between 63 and 82 = Category 2; scores between 44 and 63 = Category 3; and scores less than 44 = Category 4. Landscape Profile. Approximately 91% of the historical amount acreage of California wetlands has been lost due to reclamation and land use. Accurate estimates of estuarine wetland loss in particular are only available for the San Francisco Estuary. In spite of losing approximately 85% of its saline wetlands and almost 92% of its freshwater tidal wetlands, the SF Estuary has almost 44,500 acres of estuarine wetlands at this time, about 77% of all the estuarine wetlands in the state. Although land use varies among the estuaries of California, it has affected the distribution, abundance, size, and shape of estuarine wetlands in consistently deleterious ways. It has decreased the amount of estuarine wetland and increased the number of small wetlands, thus increasing the distance between wetlands. In the more urbanized estuaries of the South Coast, Central Coast, and SF Estuary, many wetlands are embedded in intensive land uses and bounded by levees. These conditions diminish the hydrological and ecological connectivity among the wetlands, increase their susceptibility to invasion and local catastrophic events, and reduce their overall capacity to serve society.

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Status of Water Quality in Groundwater Resources Used for Drinking-Water Supply in the Southeastern San Joaquin Valley, 2013–15: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | April 25th, 2024

Summary

The California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) investigated water quality of groundwater resources used for drinki

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Status of Water-Quality Conditions in the United States, 2010–20, Chapter C of U.S. Geological Survey Integrated Water Availability Assessment—2010–20

U.S. Geological Survey (USGS) | January 15th, 2025

Summary

Key findings related to groundwater and surface water quality problems that affect water availability include the following: Drinking-water use is affected by geogen

Key findings related to groundwater and surface water quality problems that affect water availability include the following: Drinking-water use is affected by geogenic and anthropogenic contaminants. Elevated concentrations of arsenic, manganese, strontium, radium, adjusted gross alpha, and nitrate are common in drinking water aquifers serving more than 30 million people in the United States. About one-third of stream miles assessed as surface-water sourced drinking-water supply are impaired with respect to drinking-water use, most commonly because of non-mercury metals and salinity. Health-based drinking-water violations at public water systems may disproportionately affect socially vulnerable communities. People with domestic wells as their drinking-water source are more prone to exposure to contaminants compared to people served by public water systems. Ecological water uses are predominantly limited by nutrients, sediment, temperature, pathogens, salinity, and pesticides. Contaminants without or historically without regulatory thresholds (for example, polyfluoroalkyl substances [PFAS]) have been underrepresented in previous assessments and also likely contribute to ecological degradation and human exposure. Water availability for human and ecological use is limited by elevated constituent concentrations in surface water and groundwater because of human activities. Human activities include sources (for example, inorganic and organic chemicals), processes (for example, dredging), or permanent landscape modifications (for example, dams, urbanization). Interactions between groundwater and surface water can influence water quality. Surface-water recharge can be a source of contaminants to aquifers, whereas groundwater discharge, with slow transport times, results in long-term, lagged delivery of pollutants to surface waters (especially nitrate, chloride, PFAS, and other constituents). Little information exists regarding human-health exposure risks from mixtures of geogenic and anthropogenic drinking-water contaminants. Co-occurrence and mixtures of multiple water-quality constituents, taken together, can cause compounding negative effects on water availability but mixtures are rarely measured in standard monitoring protocols. Alternative water resources could increase water availability by providing additional supply from non-traditional sources such as reclaimed wastewater, brackish and saline water, and produced water from oil and gas development. Companion chapters: U.S. Geological Survey Integrated Water Availability Assessment—2010–20, Chapter A Water Supply in the Conterminous United States, Alaska, Hawaii, and Puerto Rico, Water Years 2010–20, Chapter B Water Use Across the Conterminous United States, Water Years 2010–20, Chapter D Climate Change and Future Water Availability in the United States, Chapter E Integrated Water Availability in the Conterminous United States, 2010–20, Chapter F

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Statutory Water Rights Law And Related California Code Sections (As amended, including Statutes 2016)

California State Water Resources Control Board (SWRCB) | March 30th, 2017

Summary

The State Water Resources Control Board publishes this collection of California statutes pertaining to the law of water rights as part of its public information program.

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Still Imperilled, Still Important: The Little Hoover Commission’s Review of the CALFED Program

Little Hoover Commission | November 17th, 2005

Summary

The Sacramento-San Joaquin River Delta is a treasured and imperiled resource. And CALFED has been the best hope to restore it. The ambitious state-federal partnership is

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Page : 104

Status and Understanding of Groundwater Quality in the Sierra Nevada Regional Study Unit, 2008: California GAMA Priority Basin Project

Status and Understanding of Groundwater Quality in the South Coast Interior Groundwater Basins, 2008: California GAMA Priority Basin Project

Status of California's Wadeable Perennial Streams (2000-2007)

Status of Groundwater Quality in the California Desert Region, 2006–2008: California GAMA Priority Basin Project

Status of Groundwater Quality in the Santa Barbara Study Unit, 2011: California GAMA Priority Basin Project

Status of Perennial Estuarine Wetlands in the State of California

Status of Water Quality in Groundwater Resources Used for Drinking-Water Supply in the Southeastern San Joaquin Valley, 2013–15: California GAMA Priority Basin Project

Status of Water-Quality Conditions in the United States, 2010–20, Chapter C of U.S. Geological Survey Integrated Water Availability Assessment—2010–20

Statutory Water Rights Law And Related California Code Sections (As amended, including Statutes 2016)

Still Imperilled, Still Important: The Little Hoover Commission’s Review of the CALFED Program

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