Potential Impacts of Reduced Inflows to the Salton Sea: Forecasting Non-market Damages

American Water Resources Association (AWRA) | September 28th, 2022

Quality of Groundwater Used for Domestic Drinking-Water Supply in the Coachella Valley, 2020

U.S. Geological Survey (USGS) | January 13th, 2023

Quality of Groundwater Used for Domestic Supply in the Modesto, Turlock, and Merced Subbasins of the San Joaquin Valley, California

U.S. Geological Survey (USGS) | January 6th, 2023

More than 2 million Californians rely on groundwater from privately owned domestic wells for drinking-water supply. This report summarizes a water-quality survey of domes

More than 2 million Californians rely on groundwater from privately owned domestic wells for drinking-water supply. This report summarizes a water-quality survey of domestic and small-system drinking-water supply wells in the Modesto, Turlock, and Merced subbasins of the San Joaquin Valley where more than 78,000 residents are estimated to use privately owned domestic wells. Results indicate that inorganic and organic constituents in groundwater were respectively present above regulatory (maximum contaminant level, MCL) benchmarks for public drinking-water quality in 37 percent and 9 percent of the aquifer area used for domestic drinking-water supplies (herein, “domestic groundwater resources”). The most prevalent inorganic constituents exceeding regulatory benchmarks were nitrate, uranium, and arsenic. The only organic constituents exceeding regulatory benchmarks were the fumigant constituents 1,2,3-trichloropropane (1,2,3-TCP) and 1,2-dibromo-3-chloropropane (DBCP), but the herbicides atrazine and simazine were detected at low concentrations below one-tenth of regulatory benchmarks in 30 percent of domestic groundwater resources. Total dissolved solids (TDS) and manganese exceeded aesthetic-based (secondary maximum contaminant level [SMCL]) benchmarks for drinking water in 3 percent and 13 percent of domestic groundwater resources, respectively. Per- and polyfluoroalkyl substances (PFAS) were detected in 23 percent of domestic groundwater resources, with 4 percent exceeding California state notification or response levels for specific compounds. Total coliform bacteria were detected in 20 percent of domestic groundwater resources. Elevated concentrations of nitrate, uranium, TDS, and pesticides (fumigant constituents and herbicides) are related to agricultural land use and were typically present at shallow depths up to 75 meters below land surface. Agriculturally derived constituents were detected in wells screened below the Corcoran Clay Member of the Tulare Formation (herein, “Corcoran Clay”) in the southeastern part of the study area, where the Corcoran Clay tends to be shallower and thinner than in areas to the northwest. Nitrate, uranium, and TDS were most prevalent in the northwest part of the study area proximal to the valley trough where soils are poorly drained and agricultural land uses are predominantly grain, alfalfa, and dairy farms. Pesticides tended to occur in groundwater below coarse-grained surficial deposits and within a northwest to southeast trending band along the eastern extent of the Corcoran Clay that typically demarcates the western extent of well-drained soils associated with perennial orchard crops. Elevated concentrations of arsenic tended to occur west of this band in reducing groundwater but also sometimes co-occurred with elevated nitrate in oxic groundwater, most likely because of geochemical conditions in agriculturally affected groundwater that can enhance the mobility of arsenic from aquifer sediments.

Remote sensing is a viable tool for mapping soil salinity in agricultural lands

University of California, Davis (UC Davis) | April 7th, 2017

Report to the California State Legislature Joint Legislative Budget Committee on Reduction of Agricultural Pollution Runoff into the Sacramento-San Joaquin Delta

California State Water Resources Control Board (SWRCB) | December 1st, 2010

This report has been prepared pursuant to the requirements of the Supplemental Report to the 2008 Budget Act: “On or before March 30, 2009, State Water Resources Con

This report has been prepared pursuant to the requirements of the Supplemental Report to the 2008 Budget Act: “On or before March 30, 2009, State Water Resources Control Board (State Water Board) shall submit a report to the Joint Legislative Budget Committee and to the relevant policy committees that details: (a) the precise actions the State Water Board would have to undertake to obtain a 30 percent reduction to agricultural pollution runoff in to the Sacramento-San Joaquin Delta [Delta] and its tributary watersheds by 2012, (b) the estimated costs of those actions, and (c) which of those actions can be completed administratively and which would require legislation to implement.” The Central Valley Regional Water Quality Control Board, (Central Valley Regional Water Board) staff has determined that replacing irrigation practices that produce return flow is the only method of ensuring a 30 percent reduction in agricultural pollution runoff to the Delta by 2012. The program would be focused within the Delta and San Joaquin River watershed and apply to surface return flow (tailwater). Tailwater can convey contaminants applied to or on the land surface, such as pesticides, sediment, fertilizer, and manure. Tile water (subsurface drainage pumped to surface waters) contains naturally occurring minerals found in ground water, and may contain contaminants leached into the ground water due to application on the land surface. However, tile water is not the focus of this control strategy, since it would take longer to implement the required control technologies. Irrigation return flow is the focus of this effort, since it is more amenable to control (versus storm water runoff) and over 60 percent of the exceedances of water quality objectives we have identified occur during the irrigation season.1 A target of converting 50 percent of the irrigated acres that produce runoff to more efficient irrigation practices that produce no runoff is recommended. A 50 percent conversion target is recommended, since there are other pathways for agricultural pollutants to reach the Delta through surface waters (e.g., pesticide drift, tile water drainage), so a larger percentage reduction in irrigation runoff would be needed to ensure that the overall 30 percent pollution reduction goal is achieved. The estimated cost to the agricultural community to implement the required management practices is $250 million - $450 million in capital cost, assuming half of the one million acres of agricultural land requiring improved irrigation management systems would be targeted to meet the 2012 timeframe. Additional Central Valley Regional Water Board staff resources of up to 10 PY would be required to ensure the required practices are implemented.

Retiring Poisoned Lands in the Western San Joaquin Valley: A C-WIN Policy Brief

California Water Impact Network (C-WIN) | January 1st, 2012

It is the policy of the California Water Impact Network to: •Retire poisoned lands from irrigation so that pollution from naturally high levels of contaminants such

It is the policy of the California Water Impact Network to: •Retire poisoned lands from irrigation so that pollution from naturally high levels of contaminants such as salt, selenium, boron, mercury, arsenic and molybdenum is ended. •End wasteful and unreasonable uses of water as mandated under the California Constitution. •Slow or stop the spread of contamination to drinking water supplies, aquifers and aquatic food webs (including those with anadromous fish) where it now occurs, thereby protecting human and public health. •Redirect as much as 4 million acre-­feet of fresh water freed from retired lands to other beneficial uses within the Central Valley watershed, including fish and wildlife refuges, Delta ecosystem restoration and instream flows, and drought-­period municipal uses. •Require that solutions for retiring the poisoned lands from irrigation result in either no net change or an actual net decrease in energy consumption associated with use of those lands.

San Joaquin Valley Drainage Monitoring Program 2006 - 2010

California Department of Water Resources (DWR) | September 20th, 2013

This report shares valuable information about agricultural drainage water in order to increase the understanding of its potential impacts and improve its management in th

This report shares valuable information about agricultural drainage water in order to increase the understanding of its potential impacts and improve its management in the San Joaquin Valley. The Drainage Monitoring Program is a cooperative effort of State, federal, and local agencies.  Program staff collect, assemble, review, evaluate, and disseminate data on both the quality of drainage water as well as the depth of shallow groundwater in the San Joaquin Valley.  Fifty-two drainage sump systems are monitored for flow, sodium, sulfate, total dissolved solids, selenium, and other constituents.  Staff also combine the Department of Water Resources' data with data from over 10 other agencies for this report. DWR used depth information, gathered from approximately 1200 shallow groundwater wells, to draw Present and Potential Drainage Problem Areas Maps for the period from 2006 through 2010.  These maps show over one million acres of potentially impacted lands.  Data provided by several agencies, including the Buena Vista Water Storage District, Central California Irrigation District, Firebaugh Canal Water District, Kern County Water Agency, Panoche Water and Drainage District, San Luis Canal Company, Westlands Water District, and DWR was combined to create the maps. DWR also drew electrical conductivity (EC) maps from ECs measured in about 690 of those wells for the years 2009 and 2010.  All off the maps help inform managers of potential drainage problems in their areas due to encroachment of shallow groundwater.  The number of agencies participating is a reflection of the significance of drainage problems in the San Joaquin Valley and the potential impacts. This report focuses on five years of data collection and compilation for the calendar years 2006 thought 2010, with a special focus on historical arsenic, boron, and selenium.  In addition, pesticide and nutrient data have been added to this report for your use..

Selenium Hazards in the Salton Sea Environment— Summary of Current Knowledge to Inform Future Wetland Management

U.S. Geological Survey (USGS) | July 20th, 2023

Quaternary marine and continental shales in the western United States are sources of selenium that can be loaded into the aquatic environment through mining, agricultural

Quaternary marine and continental shales in the western United States are sources of selenium that can be loaded into the aquatic environment through mining, agricultural, and energy production processes. The mobilization of selenium from shales through agricultural irrigation has been recognized since the 1930s; however, discovery of deformities in birds and other wildlife using agricultural habitats during the 1980s spurred studies to determine the extent and effects of the contamination. Through these early studies, researchers determined that biota in the Salton Sea drainage basin was at risk from legacy selenium contamination in the Colorado River watershed.

Selenium in White Sturgeon from North San Francisco Bay: The 2015-2017 Sturgeon Derby Study

San Francisco Estuary Institute (SFEI) | October 1st, 2019

This report presents the findings from a study evaluating selenium concentrations in white sturgeon (Acipenser transmontanus) tissues collected during the 2015-2017 Sturg

This report presents the findings from a study evaluating selenium concentrations in white sturgeon (Acipenser transmontanus) tissues collected during the 2015-2017 Sturgeon Derby events in North San Francisco Bay. The goal of this study was to investigate the distribution of selenium among sturgeon tissues to inform the toxicological and regulatory interpretation of selenium measured in non-lethally collected tissues, including muscle plugs and fin rays. This technical report provides documentation of the study and presents its major findings. 

Shrinking lakes, air pollution, and human health: Evidence from California's Salton Sea

Science of the Total Environment (Elsevier) | January 7th, 2020

Due to increased water withdrawals and ongoing climate change, many inland lakes around the world are shrinking and dry lake beds can be significant sources of particulat

Due to increased water withdrawals and ongoing climate change, many inland lakes around the world are shrinking and dry lake beds can be significant sources of particulate matter air pollution. Using a natural experiment provided by the shrinking Salton Sea in California, this paper shows that each one-foot drop in lake elevation is associated with a 0.28 μg/m3 (2.6%) increase in PM2.5 concentrations. IV model results then show that Salton Sea-induced changes in PM2.5 over 1998–2014 led to increases in respiratory mortality of 1.4/yr.–15.6/yr. in the counties surrounding the lake, generating $13.2–$147.3 million in annual health costs.