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Evaluation of Processes Affecting 1,2-Dibromo-3-Chloropropane (DBCP) Concentrations in Ground Water in the Eastern San Joaquin Valley, California: Analysis of Chemical Data and Ground-Water Flow and Transport Simulations

U.S. Geological Survey (USGS) | December 17th, 1999

Summary

Future use of the sole-source aquifer near Fresno in the eastern San Joaquin Valley, California, will depend, in part, on how long 1,2-dibromo-3-chloropropane (DB

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Evaluation of Salinity Patterns and Effects of Tidal Flows and Temporary Barriers in South Delta Channels

California Department of Water Resources (DWR) | September 15th, 2016

Summary

There are several important water issues in the south Delta related to the San Joaquin River (SJR) inflow, Central Valley Project (CVP) and State Water Project (SWP) expo

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Evaluation of Surface-Water/Ground-Water Interactions in the Santa Clara River Valley, Ventura County, California

U.S. Geological Survey (USGS) | May 28th, 1999

Summary

The interactions of surface water and ground water along the Santa Clara River in Ventura County, California, were evaluated by analyzing river-discharge and water-qua

The interactions of surface water and ground water along the Santa Clara River in Ventura County, California, were evaluated by analyzing river-discharge and water-quality data and geohydrologic information collected by the U.S. Geological Survey between 1993 and 1995 for the Piru, Fillmore, and Santa Paula subbasins. Measurements of discharge and water quality were made at multiple locations along the Santa Clara River and its tributaries at eight different time periods during different releases from Lake Piru. Geologic, hydraulic, and water-quality data were collected from three new multiple-completion ground-water monitoring wells. These data, together with data collected as part of the U.S. Geological Survey Southern California Regional Aquifer-System Analysis (RASA) study, were analyzed in order to quantify rates and locations of ground-water recharge and discharge within the river, characterize the correlation of recharge and discharge rates with ground-water conditions and reservoir releases, and better characterize the three-dimensional ground-water flow system. Analysis of the data indicates that the largest amount of ground-water recharge from the river consistently occurs in the Piru subbasin. Some ground-water recharge from the river may occur in the upper part of the Fillmore subbasin. Increases in sulfate concentrations indicate that increases in flow at the lower ends of the Piru and Fillmore subbasins result from high-sulfate ground-water discharge. Increases in flow in the lower part of the Santa Paula subbasin are not accompanied by significant sulfate increases. Several sets of regressions indicate possible correlation between net flow changes in the river and depths to ground water and release rates from Lake Piru. These statistical relations may be of use for evaluating alternative Lake Piru release strategies. Data on the stable isotopes of hydrogen and oxygen from the ground-water monitoring wells that were installed as part of this investigation were used to distinguish between zones affected by recharge from the Santa Clara River and zones affected by recharge from local precipitation. Tritium data from a new multiple-completion monitoring site indicate that near the river in the upper Santa Paula subbasin, recent (post-1950) recharge water is not present at depths greater than about 350 feet below land surface. Water-level and lithologic data from the monitoring site indicate that the river and the Shallow aquifer have only limited hydraulic connection to the underlying aquifers at this location. Water-level data from the Shallow aquifer and from an in-stream drive point were used in an analytic model to estimate hydraulic properties governing stream-aquifer interactions in the upper Santa Paula subbasin. Hydraulic conductivities in all the USGS monitoring wells were estimated on the basis of slug tests.

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Evaluation of the California State Water Resource Control Board’s Bioassessment Program

California State Water Resources Control Board (SWRCB) | May 15th, 2009

Summary

The State of California’s bioassessment, monitoring and assessment (M&A), and water quality standards (WQS) programs were reviewed in January 2008 using the

The State of California’s bioassessment, monitoring and assessment (M&A), and water quality standards (WQS) programs were reviewed in January 2008 using the U.S. EPA’s Critical Technical Elements and Programmatic Review process (Barbour and Yoder 2008; Quasney and Yoder 2008), which evaluates key components of these state programs and existing and planned capacities. The review process results in technical, policy, and management recommendations for building, refining and maintaining functional and effective bioassessment and M&A tools that support the full spectrum of WQS and management programs. This review was conducted by a two-person review team with national expertise at evaluating, building, and implementing state and tribal programs. Bioassessment, the use of resident aquatic biota as direct indicators of the biological integrity of water bodies, is a powerful tool for water resource regulatory programs. The need for state water quality agencies to develop and maintain robust bioassessment programs is underscored by the National Research Council’s critical review of state TMDL, M&A, and WQS programs (National Research Council 2001). The NRC’s review makes clear that all states need better biological endpoints, adequate M&A, and tiered aquatic life uses (TALU) in order to develop and refine appropriate and effective WQS that result in more accurate and appropriate protection for biological resources. While the federal Clean Water Act (CWA) has long required states to protect and restore the chemical, physical, and biological integrity of the nation’s waters, the California Water Boards have only recently begun to develop the tools, expertise and capacity that they will need in order to implement modernized WQS that protect biological integrity. However, because of the substantial investment in the development of bioassessment tools made since the mid-1990s by the state’s Department of Fish and Game, California is now positioned to initiate the process of integrating bioassessments into its WQS and monitoring and assessment programs via the development and implementation of narrative and numeric biocriteria.

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Evaluation of the characteristics, discharge, and water quality of selected springs at Fort Irwin National Training Center, San Bernardino County, California

U.S. Geological Survey (USGS) | March 29th, 2024

Summary

Eight springs and seeps at Fort Irwin National Training Center were described and categorized by their general characteristics, discharge, geophysical properties, and wat

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

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

Summary

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

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Evaluation of water quality in the Langford Valley–Irwin Groundwater Subbasin, Fort Irwin National Training Center, California, 1993–2019

U.S. Geological Survey (USGS) | January 9th, 2026

Summary

The U.S. Army Fort Irwin National Training Center (NTC), 120 miles northeast of Los Angeles in the Mojave Desert of California, obtains its potable water supply from the

The U.S. Army Fort Irwin National Training Center (NTC), 120 miles northeast of Los Angeles in the Mojave Desert of California, obtains its potable water supply from the Bicycle Valley and Langford Valley groundwater basins; Langford Valley groundwater basin is further subdivided into the Langford Well Lake and Irwin groundwater subbasins. The Irwin groundwater subbasin contains younger, unconsolidated deposits that have a saturated thickness of as much as 200 feet (ft) and a lower aquifer within older unconsolidated deposits as thick as 650 ft. Groundwater recharge under predevelopment conditions (before 1941) occurred primarily from infiltration of intermittent streamflow in small washes that cross the Irwin groundwater subbasin. Since that time, groundwater recharge has increased because of growth of the NTC in recent years and as a result of other processes, including (1) infiltration of treated wastewater into the aquifer through ponds near the NTC wastewater treatment facility (WWTF) and (2) infiltration of imported water and treated wastewater used for landscape irrigation at base housing and athletic fields. Water samples were collected from 17 wells and analyzed for field parameters, chemical constituents, and isotope composition in the Irwin groundwater subbasin between 2014 and 2019. These data were supplemented with water- chemistry data collected during 1993–95 and at other times if available. Between 1993–95 and 2015–19, median dissolved solids and nitrate concentrations in water from wells in the Irwin groundwater subbasin increased from 620 to 1,030 milligrams per liter (mg/L) and from 2.8 to 4.5 mg/L as nitrogen, respectively. After 2014, dissolved solids and nitrate concentrations in water from wells near the NTC WWTF decreased as a result of changes in source water quality attributable to reverse osmosis of treated drinking water delivered within the Irwin groundwater subbasin and to increased levels of treatment at the NTC WWTF. Based on delta oxygen- 18 and delta deuterium isotope data, increases in dissolved solids concentrations in water from most wells were consistent with evaporation prior to recharge and mobilization of soluble salts from the unsaturated zone. Arsenic and fluoride concentrations in water from wells decreased between 1993–95 and 2015–19 as the basin filled with treated wastewater, but 2015–19 concentrations generally exceeded the California State Water Resources Control Board maximum contaminant levels of 10 micrograms per liter for arsenic and 2 mg/L for fluoride. Most groundwater in the Irwin groundwater subbasin has unadjusted carbon- 14 ages ranging from 18,400 to 12,350 years before present. However, water from well 10E3, located along the wash near the subbasin outflow in the southeastern part of the Irwin groundwater subbasin, contained measurable tritium, which is consistent with infiltration of intermittent streamflow and groundwater recharge from the wash after 1952. Chemical and isotopic data indicate that treated wastewater is present in water from most wells in the upper aquifer that underlies the Irwin groundwater subbasin. Wells were not sampled to adequately determine the extent of treated wastewater and changes in water quality within the lower aquifer that underlies the Irwin groundwater subbasin.

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Examination of the ocean as a source for atmospheric microplastics

PLOS | May 12th, 2020

Summary

Global plastic litter pollution has been increasing alongside demand since plastic products gained commercial popularity in the 1930s. Current plastic pollutant research

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Executive Summary: An Evaluation of Compensatory Mitigation Projects Permitted Under Clean Water Act Section 401 by the California State Water Resources Control Board, 1991-2002

California State Water Resources Control Board (SWRCB) | August 1st, 2007

Summary

The purpose of this project, which was funded by the California State Water Resources Control Board (SWRCB), was to evaluate the compliance and wetland conditio

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Exploring scientific and management implications of upper trophic level food webs in the Delta

Delta Stewardship Council (Delta Council) | April 17th, 2024

Summary

The Sacramento-San Joaquin Delta (the Delta) has complex and evolving ecosystems characterized by multiple food webs that vary in time and space. Here, food webs are defi

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Evaluation of Processes Affecting 1,2-Dibromo-3-Chloropropane (DBCP) Concentrations in Ground Water in the Eastern San Joaquin Valley, California: Analysis of Chemical Data and Ground-Water Flow and Transport Simulations

Evaluation of Salinity Patterns and Effects of Tidal Flows and Temporary Barriers in South Delta Channels

Evaluation of Surface-Water/Ground-Water Interactions in the Santa Clara River Valley, Ventura County, California

Evaluation of the California State Water Resource Control Board’s Bioassessment Program

Evaluation of the characteristics, discharge, and water quality of selected springs at Fort Irwin National Training Center, San Bernardino County, California

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

Evaluation of water quality in the Langford Valley–Irwin Groundwater Subbasin, Fort Irwin National Training Center, California, 1993–2019

Examination of the ocean as a source for atmospheric microplastics

Executive Summary: An Evaluation of Compensatory Mitigation Projects Permitted Under Clean Water Act Section 401 by the California State Water Resources Control Board, 1991-2002

Exploring scientific and management implications of upper trophic level food webs in the Delta

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