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

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

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.

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

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

The California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) investigated water quality of groundwater resources used for drinking-water supplies in the Madera-Chowchilla, Kings, Kaweah, Tule, and Tulare Lake groundwater subbasins of the southeastern San Joaquin Valley during 2013–15. The study focused primarily on groundwater resources used for domestic-supply wells in the southeastern San Joaquin Valley (SESJV-D), which correspond mostly to shallower parts of aquifer systems, compared to the groundwater resources used for public-supply wells in the southeastern San Joaquin Valley (SESJV-P). The investigation had three components: (1) characterization of the status of water quality in the SESJV-D, (2) comparison between water quality in the SESJV-D and SESJV-P, and (3) identification of natural and anthropogenic factors that potentially could affect water quality in these resources.

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

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 

Stipulated Agreement: Department of Water and Power of the City of Los Angeles vs. Board of Supervisors of the County of Inyo et al

Superior Court of California, County of Inyo | October 21st, 1991

Stockton East Water District - Groundwater Recharge Basin, Southeast Recharge Basin

U.S. Bureau of Reclamation (USBR) | February 15th, 2018

Quality regulations (40 CFR 1500 - 1508), and Department of the Interior Regulations (43 CFR Part 46), the Bureau of Reclamation (Reclamation) prepared this env

Quality regulations (40 CFR 1500 - 1508), and Department of the Interior Regulations (43 CFR Part 46), the Bureau of Reclamation (Reclamation) prepared this environmental assessment to evaluate and disclose potential environmental impacts associated with providing funds to the Stockton East Water District (SEWD) in San Joaquin County, California to construct a new 73-acre groundwater recharge basin . Reclamation would provide $300,000 through the Drought Response Program to SEWD for the development of a groundwater recharge basin. The Drought Response Program is a program designed to help water users develop drought contingency plans and build long-term drought resilience.

Stony Creek Fan Conjunctive Water Management Plan Feasibility Investigation

Glenn-Colusa Irrigation District | February 15th, 2004

Strategic Salt Accumulation Land and Transportation Study (SSALTS) Final Phase 1 Report – Identification and Characterization of Existing Salt Accumulation Areas

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | December 13th, 2013

The purpose of the Strategic Salt Accumulation Land and Transportation Study (SSALTS) is to identify the range of viable Central Valley alternatives for salt disposal to

The purpose of the Strategic Salt Accumulation Land and Transportation Study (SSALTS) is to identify the range of viable Central Valley alternatives for salt disposal to provide input for consideration during development of the Salt and Nutrient Management Plan (SNMP) for the region under the jurisdiction of the Central Valley Regional Water Quality Control Board (Central Valley RWQCB). The findings will be used to guide discussions regarding establishment of regional salt management policies and the need for changes to the existing Central Valley RWQCB Water Quality Control Plans (Basin Plans) to facilitate salt disposal in a manner that is most beneficial to the region and consistent with the State Water Resource Control Board (SWRCB) Recycled Water Policy. This work is being conducted under the direction of the Central Valley Salinity Alternatives for Long- Term Sustainability (CV-SALTS) initiative, which is developing the SNMP for the Central Valley. The SSALTS project is being conducted in three phases: Phase 1: Identify and Characterize Existing Salt Accumulation Study Areas–Selection of representative Study Areas to serve as prototype situational examples to facilitate discussions regarding salt accumulation and disposal in the Central Valley. Each of these Study Areas is being characterized to establish baseline information that may be used to support development of salt disposal alternatives in subsequent project phases. Phase 2: Develop Potential Salt Management Strategies–SSALTS will develop potential long- term salt disposal alternatives in three parts: (1) In-Valley alternatives; (2) Out-of-Valley alternatives; and (3) hybrid alternatives that combine In-Valley and Out-of-Valley salt disposal options. Phase 3: Evaluate Potential Salt Disposal Alternatives to Identify Acceptable Alternatives for Implementation – Alternatives developed under Phase 2 will be evaluated using selected feasibility criteria (e.g., regulatory, institutional, economic, technological, etc.). The outcome of this evaluation will be the identification and prioritization of acceptable salt disposal alternatives for potential incorporation into Central Valley SNMP as salt management implementation measures. This draft report represents the findings of Phase 1. Subsequent phases of SSALTS will be implemented following completion of this phase.  

Strategic Salt Accumulation Land and Transportation Study (SSALTS) Final Phase 2 Report – Development of Potential Salt Management Strategies

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | October 1st, 2014

The purpose of the Strategic Salt Accumulation Land and Transportation Study (SSALTS) is to identify the range of viable Central Valley alternatives for salt disposal to

The purpose of the Strategic Salt Accumulation Land and Transportation Study (SSALTS) is to identify the range of viable Central Valley alternatives for salt disposal to provide input for consideration during development of the Salt and Nutrient Management Plan (SNMP) for the region under the jurisdiction of the Central Valley Regional Water Quality Control Board (Central Valley RWQCB). The findings will be used to guide discussions regarding establishment of regional salt management policies and the need for changes to the existing Central Valley RWQCB Water Quality Control Plans (Basin Plans) to facilitate salt disposal in a manner that is most beneficial to the region and consistent with the State Water Resource Control Board (SWRCB) Recycled Water Policy. This work is being conducted under the direction of the Central Valley Salinity Alternatives for Long- Term Sustainability (CV-SALTS) initiative, which is developing the SNMP for the Central Valley. The SSALTS project is being conducted in three phases: Phase 1: Identify and Characterize Existing Salt Accumulation Study Areas–Selection of representative Study Areas to serve as prototype situational examples to facilitate discussions regarding salt accumulation and disposal in the Central Valley. Each of these Study Areas is being characterized to establish baseline information that may be used to support development of salt disposal alternatives in subsequent project phases. Phase 2: Develop Potential Salt Management Strategies–SSALTS will develop potential long- term salt disposal alternatives in three parts: (1) In-Valley alternatives; (2) Out-of-Valley alternatives; and (3) hybrid alternatives that combine In-Valley and Out-of-Valley salt disposal options. Phase3: Evaluate Potential Salt Disposal Alternatives to Identify Acceptable Alternatives for Implementation – Alternatives developed under Phase 2 will be evaluated using selected feasibility criteria (e.g., regulatory, institutional, economic, technological, etc.). The outcome of this evaluation will be the identification and prioritization of acceptable salt disposal alternatives for potential incorporation into Central Valley SNMP as salt management implementation measures. The Phase 1 report was finalized in December 2013. This report summarizes the findings of Phase 2. Phase 3 work will begin after the stakeholders have reviewed the Phase 2 report and provided comments.

Stratigraphic controls on seawater intrusion and implications for groundwater management, Dominguez Gap area of Los Angeles, California, USA

Hydrogeology Journal (Springer) | May 30th, 2009

Groundwater pumping has led to extensive waterlevel declines and seawater intrusion in coastal Los Angeles, California (USA). A SUTRA-based solute-transport model was dev

Groundwater pumping has led to extensive waterlevel declines and seawater intrusion in coastal Los Angeles, California (USA). A SUTRA-based solute-transport model was developed to test the hydraulic implications of a sequence-stratigraphic model of the Dominguez Gap area and to assess the effects of water-management scenarios. The model is two-dimensional, vertical and follows an approximate flow line extending fromthe Pacific Ocean through the Dominguez Gap area. Results indicate that a newly identified fault system can provide a pathway for transport of seawater and that a stratigraphic boundary located between the Bent Spring and Upper Wilmington sequences may control the vertical movement of seawater. Three 50-year water-management scenarios were considered: (1) no change in water-management practices; (2) installation of a slurry wall; and (3) raising inland water levels to 7.6m above sea level. Scenario 3 was the most effective by reversing seawater intrusion. The effects of an instantaneous 1-m sealevel rise were also tested using water-management scenarios 1 and 3. Results from two 100-year simulations indicate that a 1-m sea-level rise may accelerate seawater intrusion for scenario 1; however, scenario 3 remains effective for controlling seawater intrusion.

Strawberry Case Study: What If Farmers Had to Pay for Water?

New York Times | December 29th, 2023

While American farmers elsewhere have watered their crops by freely pumping the groundwater beneath their land, growers in Pajaro must pay hefty fees for irrigation water

While American farmers elsewhere have watered their crops by freely pumping the groundwater beneath their land, growers in Pajaro must pay hefty fees for irrigation water — making it one of the most expensive places to grow food in the country, if not the world. The cost: Up to $400 per acre-foot, a standard measurement equal to water covering one acre, one foot deep. The fees bring in $12 million a year, which is used to recycle, restore and conserve the region’s groundwater.