Comparing Domestic and Public-Supply Groundwater Quality in the Northern San Joaquin Valley, 2019: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | June 5th, 2023

Analysis of construction data for wells included in the comparative assessment indicated that, although depth to top of perforations are comparable for domestic and publi

Analysis of construction data for wells included in the comparative assessment indicated that, although depth to top of perforations are comparable for domestic and public-supply wells in the Northern San Joaquin Valley (median depth about 60 meters [m]), public-supply wells have longer perforation intervals and extend to deeper parts of the aquifer system (exceeding 120 m) than domestic wells that typically draw exclusively from the shallower aquifer system in the upper 80 m of unconsolidated sediments. Analysis of the vertical and lateral distribution of constituents of interest (nitrate, fumigants, and arsenic) across domestic- and public-supply aquifers indicated that nitrate is prevalent in shallow aquifers throughout the Northern San Joaquin Valley but is potentially diluted by mixing with deeper, older groundwater at long-screened public-supply wells. Fumigants were prevalent in areas of urban and agricultural land use in the western part of the Northern San Joaquin Valley, particularly in areas near Lodi, California, but 1,2,3-TCP was more widespread than DBCP and was detected in shallow and deeper parts of the aquifer system, potentially because of its recalcitrance in groundwater and ability to be detected at low concentrations. Arsenic was most prevalent in the western part of the Northern San Joaquin Valley with proximity to deltaic sediments and was detected at high RCs in wells tapping shallow and deep parts of the aquifer system.

Comparison of potential drinking water source contamination across one hundred U.S. cities

Nature Portfolio (Springer Nature) | December 13th, 2021

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds. B

Drinking water supplies of cities are exposed to potential contamination arising from land use and other anthropogenic activities in local and distal source watersheds. Because water quality sampling surveys are often piecemeal, regionally inconsistent, and incomplete with respect to unregulated contaminants, the United States lacks a detailed comparison of potential source water contamination across all of its large cities. Here we combine national scale geospatial datasets with hydrologic simulations to compute two metrics representing potential contamination of water supplies from point and nonpoint sources for over a hundred U.S. cities. We reveal enormous diversity in anthropogenic activities across watersheds with corresponding disparities in the potential contamination of drinking water supplies to cities. Approximately 5% of large cities rely on water that is composed primarily of runoff from non-pristine lands (e.g., agriculture, residential, industrial), while four-fifths of all large cities that withdraw surface water are exposed to treated wastewater in their supplies.

Concentrations for total dissolved solids, arsenic, boron, fluoride, and nitrite-nitrate for wells sampled in the Mojave Water Agency Management Area

U.S. Geological Survey (USGS) | July 1st, 2001

CV SALTS Prioritization & Optimization Study Year 1 Progress Report

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | March 24th, 2023

CV-SALTS Central Valley Region Salt & Nitrate Control Program Surveillance and Monitoring Program

Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) | February 3rd, 2023

The prioritized Nitrate Control Program and phased Salt Control Program are designed to address both legacy and ongoing salt and nitrate accumulation issues in groundwate

The prioritized Nitrate Control Program and phased Salt Control Program are designed to address both legacy and ongoing salt and nitrate accumulation issues in groundwater and salinity concerns in surface waters. However, the primary focus of early actions being implemented under the Nitrate Control Program (i.e., the first ten years) is on groundwater quality and in particular nitrate impacts to drinking water supplies. The overarching management goals and priorities of the SNCP are to: Ensure safe drinking water supply; Reduce salt and nitrate loading so that ongoing discharges neither threaten to degrade high quality waters absent appropriate findings by the Central Valley Board, nor cause or contribute to exceedances of water quality objectives; and Implement long-term, managed restoration of impaired waterbodies.

CV-SALTS Modesto Management Zone Implementation Plan

Valley Water Collaborative | September 5th, 2023

The Central Valley Regional Water Quality Control Board (Central Valley Water Board) adopted amendments to the Water Quality Control Plan for the Sacramento River and San

The Central Valley Regional Water Quality Control Board (Central Valley Water Board) adopted amendments to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins and the Water Quality Control Plan for the Tulare Lake Basin (Basin Plans) to incorporate a Salt and Nitrate Control Program. The Nitrate Control Program is designed to achieve the following three management goals in the Central Valley Region: • Goal 1 – Ensure a safe drinking water supply; • Goal 2 – Reduce salt and nitrate loading so that ongoing discharges neither threaten to degrade high quality waters absent appropriate findings by the Central Valley Water Board nor cause or contribute to exceedances of water quality objectives; and, • Goal 3 – Implement long-term, managed restoration of impaired water bodies. Click here for CV-SALTS Priority 1 publication index

CV-SALTS Preliminary Management Zone Proposal for Priority 2 Management Zones

Valley Water Collaborative | December 30th, 2024

The Nitrate Control Program is designed to achieve the following three management goals in the Central Valley Region: Goal 1 – Ensure a safe drinking water

The Nitrate Control Program is designed to achieve the following three management goals in the Central Valley Region: Goal 1 – Ensure a safe drinking water supply; Goal 2 – Reduce salt and nitrate loading so that ongoing discharges neither threaten to degrade high quality waters absent appropriate findings by the Central Valley Water Board nor cause or contribute to exceedances of water quality objectives; and, Goal 3 – Implement long-term, managed restoration of impaired water bodies.

CV-SALTS Turlock Management Zone Implementation Plan

Valley Water Collaborative | September 5th, 2023

The Central Valley Regional Water Quality Control Board (Central Valley Water Board) adopted amendments to the Water Quality Control Plan for the Sacramento River and San

The Central Valley Regional Water Quality Control Board (Central Valley Water Board) adopted amendments to the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins and the Water Quality Control Plan for the Tulare Lake Basin (BasinPlans) to incorporate a Salt and Nitrate Control Program. The Nitrate Control Program is designed to achieve the following three management goals in the Central Valley Region: • Goal 1 – Ensure a safe drinking water supply; • Goal 2 – Reduce salt and nitrate loading so that ongoing discharges neither threaten to degrade high quality waters absent appropriate findings by the Central Valley Water Board nor cause or contribute to exceedances of water quality objectives; and, • Goal 3 – Implement long-term, managed restoration of impaired water bodies. Click here for an index of CV-SALTS Management Zone publications

Drinking water nitrate and human health: An updated review

Multidisciplinary Digital Publishing Institute (MDPI) | July 23rd, 2018

Evaluation of the Source and Transport of High Nitrate Concentrations in Ground Water, Warren Subbasin, California

U.S. Geological Survey (USGS) | December 13th, 2003

From early 1995 through 2001, nitrate (NO3) concentrations in ground water in the Warren subbasin, California, increased from a background concentration of 10 milligrams

From early 1995 through 2001, nitrate (NO3) concentrations in ground water in the Warren subbasin, California, increased from a background concentration of 10 milligrams per liter (mg/L) to more than the U.S. Environmental Protection Agency (USEPA) water-quality maximum contaminant level of 44 mg/L (10 mg/L as nitrogen). This increase coincided with an artificial ground-water recharge program implemented by the local water district, Hi-Desert Water District (HDWD), to reverse ground-water level declines of as much as 300 ft. Major findings on ground-water quality from this study are the following: •Septage from septic tanks was the primary source of NO3 to the ground-water system. •Rising ground-water levels, resulting from the artificial-recharge program, entrained high-NO3 septage stored in the unsaturated zone. •The potential for ground-water contamination should be evaluated before beginning an artificial- recharge program in an area that uses septic tanks.