Colorado River

Groundwater in California

Public Policy Institute of California (PPIC) | June 6th, 2024

Groundwater Management Principles and Strategies to Monitor, Analyze and Minimize Impacts to Drinking Water Wells: A Framework for State Action to Support Drought Resilient Communities

California Department of Water Resources (DWR) | December 15th, 2021

This framework was developed in response to support drinking water access for groundwater-dependent communities.

This framework was developed in response to support drinking water access for groundwater-dependent communities.

Groundwater quality data in the Mojave study unit, 2008: Results from the California GAMA Program

U.S. Geological Survey (USGS) | July 1st, 2009

Groundwater Quality in Coachella Valley, California

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

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monito

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Coachella Valley is one of the study areas being evaluated. The Coachella study area is approximately 820 square miles (2,124 square kilometers) and includes the Coachella Valley groundwater basin (California Department of Water Resources, 2003). Coachella Valley has an arid climate, with average annual rainfall of about 6 inches (15 centimeters). The runoff from the surrounding mountains drains to rivers that flow east and south out of the study area to the Salton Sea. Land use in the study area is approximately 67 percent (%) natural, 21% agricultural, and 12% urban. The primary natural land cover is shrubland. The largest urban areas are the cities of Indio and Palm Springs (2010 populations of 76,000 and 44,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Coachella Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Coachella Valley are completed to depths between 490 and 900 feet (149 to 274 meters), consist of solid casing from the land surface to a depth of 260 to 510 feet (79 to 155 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to the Salton Sea and Imperial Valley areas.

Groundwater quality in shallow aquifers in the western Mojave Desert, California

U.S. Geological Survey (USGS) | May 28th, 2019

 The Mojave Basin Shallow Aquifer study unit (Mojave) covers approximately 4,680 square kilometers (2,908 square miles) in the western part of the Mojave Desert in San B

 The Mojave Basin Shallow Aquifer study unit (Mojave) covers approximately 4,680 square kilometers (2,908 square miles) in the western part of the Mojave Desert in San Bernardino County. The study unit consists of groundwater basins along the Mojave River, the El Mirage Valley groundwater basin, and part of the Harper Valley groundwater basin. The Mojave study unit was divided into two study areas—the floodplain study area along the Mojave River and the regional study area surrounding and underlying the floodplain study area. Aquifers in the floodplain study area consist of coarse granitic river-channel and floodplain alluvium deposited by the Mojave River.  Aquifers in the regional study area consist of alluvium derived from older stream deposits, locally derived alluvial fans, playa lake deposits, and fractured bedrock (Stamos and others, 2001; Groover and Izbicki, 2019). This study examined the quality of groundwater resources used for domestic drinking-water supply. 

Groundwater Quality in the Colorado River Basins, California

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

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monito

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Four groundwater basins along the Colorado River make up one of the study areas being evaluated. The Colorado River study area is approximately 884 square miles (2,290 square kilometers) and includes the Needles, Palo Verde Mesa, Palo Verde Valley, and Yuma groundwater basins (California Department of Water Resources, 2003). The Colorado River study area has an arid climate and is part of the Sonoran Desert. Average annual rainfall is about 3 inches (8 centimeters). Land use in the study area is approximately 47 percent (%) natural (mostly shrubland), 47% agricultural, and 6% urban. The primary crops are pasture and hay. The largest urban area is the city of Blythe (2010 population of 21,000). Groundwater in these basins is used for public and domestic water supply and for irrigation. The main waterbearing units are gravel, sand, silt, and clay deposited by the Colorado River or derived from surrounding mountains. The primary aquifers in the Colorado River study area are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in the Colorado River basins are completed to depths between 230 and 460 feet (70 to 140 meters), consist of solid casing from the land surface to a depth of 130 of 390 feet (39 to 119 meters), and are screened or perforated below the solid casing. The main source of recharge to the groundwater systems in the Needles, Palo Verde Mesa, and Palo Verde Valley basins is the Colorado River; in the Yuma basin, the main source of recharge is from subsurface flow from the groundwater basins to the west. Groundwater discharge is primarily to pumping wells, evapotranspiration, and, locally, to the Colorado River.

Groundwater Quality of the Lucerne Valley Groundwater Basin, California

U.S. Geological Survey (USGS) | July 7th, 2022

Anthropogenic activities, including groundwater withdrawals, return flow from irrigated agriculture, and treated wastewater-effluent disposal have the potential to affect

Anthropogenic activities, including groundwater withdrawals, return flow from irrigated agriculture, and treated wastewater-effluent disposal have the potential to affect groundwater quality in the Lucerne Valley groundwater basin, located in the southwest Mojave Desert. Questions regarding the current state and potential future of groundwater quality in this basin were addressed by (1) considering groundwater data from and findings of historical water-quality studies, (2) evaluating recent (1990–2021) U.S. Geological Survey water-quality and geochemical-tracer data, and (3) assessing groundwater-quality results from samples collected in 2021 to better understand the transport of applied treated wastewater effluent in the subsurface and associated effects of this practice on water quality. As observed by previous studies, differences in groundwater quality existed among the upper, middle, and lower aquifers of the Lucerne Valley groundwater basin, with the lower aquifer characterized by high dissolved-solid content relative to the middle and upper aquifers. Stable and radioisotope tracers indicate that most of the groundwater sampled in the basin was recharged during cooler, wetter climate conditions than those of the present day (2022). Analyses of the 2021 samples collected to examine the subsurface transport of applied treated wastewater effluent were not conclusive but indicate that water from applied treated wastewater effluent is currently (2022) limited to the upper aquifer and likely to remain so given the extensive confining unit below the upper aquifer.

Groundwater Sustainability Plan Implementation: A Guide to Annual Reports, Periodic Evaluations, and Plan Amendments

California Department of Water Resources (DWR) | October 15th, 2023

This document provides guidance to groundwater sustainability agencies (GSAs) preparing Annual Reports, Periodic Evaluations, and Groundwater Sustainability Plan (GSP or

This document provides guidance to groundwater sustainability agencies (GSAs) preparing Annual Reports, Periodic Evaluations, and Groundwater Sustainability Plan (GSP or Plan) Amendments under the Sustainable Groundwater Management Act (SGMA or Act) and the GSP Regulations. This guidance document does not create any new requirements or obligations for GSAs but is intended to clarify the necessary content of the documents already required by SGMA and the GSP Regulations.

Groundwater-dependent ecosystem map exposes global dryland protection needs

Nature Portfolio (Springer Nature) | July 17th, 2024

Guidelines for the Small Community Drought Relief Program

California Department of Water Resources (DWR) | September 20th, 2022