Using the new information, along with the recently acquired seismic reflection data, USGS scientists and co-workers have been able to develop a much more detailed understanding of the stratigraphy and structure of the Central and West Coast Basins.

Situated on a semiarid coastal plain, the greater Los Angeles area relies significantly on groundwater for its water supply. Historical groundwater development of the Central and West Coast Basins caused a large decline in groundwater levels and seawater intrusion. These effects led to the adjudication of the basins in the early of 1960s and initiation of a series of groundwater management activities, including construction and operation of injection barriers, recharge of groundwater basins through spreading grounds, restriction of groundwater withdrawal in certain periods, and use of imported and reclaimed water in lieu of some pumping.
Groundwater currently meets almost 40% of water demand for 4 million people who live in the Central and West Coast Basins. To improve the scientific understanding and sustainable management of the basins, the U.S. Geological Survey (USGS), in cooperation with the Water Replenishment District of Southern California (WRDSC), has conducted multiple studies in the past 17 years. Most of the studies have been focused on the following 3 perspectives:
- research drilling and data collection,
- geohydrologic and geochemical analyses, and
- model or database development and application.
The drilling and data collection have been extensive. As of July, 2016, the USGS has constructed 57 deep, multiple-well monitoring sites throughout the Central and West Coast Basins. Detailed hydrologic and water-quality data have been collected from these sites. An important aspect of the drilling in recent years has been the collection and interpretation of core samples and advanced geophysical logs from the boreholes of each drilling site. Using the new information, along with the recently acquired seismic reflection data, USGS scientists and co-workers have been able to develop a much more detailed understanding of the stratigraphy and structure of the Central and West Coast Basins.
Geohydrologic/geochemical analyses and modeling of recent years have been focused on the development of a sequence-stratigraphy-based, regional-scale groundwater flow model. The model also includes a recharge sub-model for watershed-wide, precipitation-runoff-infiltration simulation. Future plans for application of the regional groundwater flow model include:
- assessment of alternative water-management strategies, such as conjunctive use and aquifer storage and recovery (ASR),
- identification of potential flow paths and distribution of different sources of water (seawater, imported water, reclaimed water) after they enter into the basins,
- simulation of contaminant movement by coupling the flow model with a transport module, and
- evaluation of the impacts of urbanization on the groundwater system, such as an increase in pumpage, lining of rivers and reduction in pervious area, and introduction of new sources of water into the basins.
A web-based, integrated hydrogeological database is also in development for storage and access of various geological, hydrological and water chemistry data that were built into the regional groundwater flow model.
Below are other science projects associated with this project.
Los Angeles Coastal Plain Groundwater-flow Model
Installation of two multiple-well monitoring sites near a proposed supplemental recharge well project, Central Basin, Los Angeles County, Federal Fiscal Year 2016
Below are publications associated with this project.
Estimating spatially and temporally varying recharge and runoff from precipitation and urban irrigation in the Los Angeles Basin, California
Characterization of potential transport pathways and implications for groundwater management near an anticline in the Central Basin area, Los Angeles County, California
Groundwater quality in the Coastal Los Angeles Basin, California
Research to More Effectively Manage Critical Ground-Water Basins
Ground-water quality of coastal aquifer systems in the West Coast Basin, Los Angeles County, California, 1999-2002
Geohydrology, Geochemistry, and Ground-Water Simulation-Optimization of the Central and West Coast Basins, Los Angeles County, California
Saltwater intrusion in Los Angeles area coastal aquifers: The marine connection
Below are partners associated with this project.
- Overview
Using the new information, along with the recently acquired seismic reflection data, USGS scientists and co-workers have been able to develop a much more detailed understanding of the stratigraphy and structure of the Central and West Coast Basins.
Sources/Usage: Public Domain. Visit Media to see details.Map of the Los Angeles area featuring groundwater management activities, including injection barrier projects, and the location of spreading grounds (modified from Reichard and others, 2003). A solid red line indicates a fault, a dashed purple lines indicates a fold axis, yellow dashed lines indicate injection barriers, and solid blue lines indicate rivers and streams. (Public domain.) Situated on a semiarid coastal plain, the greater Los Angeles area relies significantly on groundwater for its water supply. Historical groundwater development of the Central and West Coast Basins caused a large decline in groundwater levels and seawater intrusion. These effects led to the adjudication of the basins in the early of 1960s and initiation of a series of groundwater management activities, including construction and operation of injection barriers, recharge of groundwater basins through spreading grounds, restriction of groundwater withdrawal in certain periods, and use of imported and reclaimed water in lieu of some pumping.
Groundwater currently meets almost 40% of water demand for 4 million people who live in the Central and West Coast Basins. To improve the scientific understanding and sustainable management of the basins, the U.S. Geological Survey (USGS), in cooperation with the Water Replenishment District of Southern California (WRDSC), has conducted multiple studies in the past 17 years. Most of the studies have been focused on the following 3 perspectives:
- research drilling and data collection,
- geohydrologic and geochemical analyses, and
- model or database development and application.
The drilling and data collection have been extensive. As of July, 2016, the USGS has constructed 57 deep, multiple-well monitoring sites throughout the Central and West Coast Basins. Detailed hydrologic and water-quality data have been collected from these sites. An important aspect of the drilling in recent years has been the collection and interpretation of core samples and advanced geophysical logs from the boreholes of each drilling site. Using the new information, along with the recently acquired seismic reflection data, USGS scientists and co-workers have been able to develop a much more detailed understanding of the stratigraphy and structure of the Central and West Coast Basins.
Geohydrologic/geochemical analyses and modeling of recent years have been focused on the development of a sequence-stratigraphy-based, regional-scale groundwater flow model. The model also includes a recharge sub-model for watershed-wide, precipitation-runoff-infiltration simulation. Future plans for application of the regional groundwater flow model include:
- assessment of alternative water-management strategies, such as conjunctive use and aquifer storage and recovery (ASR),
- identification of potential flow paths and distribution of different sources of water (seawater, imported water, reclaimed water) after they enter into the basins,
- simulation of contaminant movement by coupling the flow model with a transport module, and
- evaluation of the impacts of urbanization on the groundwater system, such as an increase in pumpage, lining of rivers and reduction in pervious area, and introduction of new sources of water into the basins.
A web-based, integrated hydrogeological database is also in development for storage and access of various geological, hydrological and water chemistry data that were built into the regional groundwater flow model.
- Science
Below are other science projects associated with this project.
Los Angeles Coastal Plain Groundwater-flow Model
The Los Angeles Coastal Plain Groundwater-flow Model (LACPGM) is a tool to help water managers better understand groundwater flow and seawater intrusion in the Los Angeles coastal plain basins. It is the culmination of years of data collection and studies in the area and builds on our understanding of the area’s geology and hydrology obtained through the geologic and groundwater flow models.Installation of two multiple-well monitoring sites near a proposed supplemental recharge well project, Central Basin, Los Angeles County, Federal Fiscal Year 2016
The Water Replenishment District of Southern California (WRD) is planning to construct an advanced water treatment facility and three supplemental injection wells in a recharge area in the coastal plain of Los Angeles County. - Publications
Below are publications associated with this project.
Estimating spatially and temporally varying recharge and runoff from precipitation and urban irrigation in the Los Angeles Basin, California
A daily precipitation-runoff model, referred to as the Los Angeles Basin watershed model (LABWM), was used to estimate recharge and runoff for a 5,047 square kilometer study area that included the greater Los Angeles area and all surface-water drainages potentially contributing recharge to a 1,450 square kilometer groundwater-study area underlying the greater Los Angeles area, referred to as the LAuthorsJoseph A. Hevesi, Tyler D. JohnsonCharacterization of potential transport pathways and implications for groundwater management near an anticline in the Central Basin area, Los Angeles County, California
The Central Groundwater Basin (Central Basin) of southern Los Angeles County includes ~280 mi2 of the Los Angeles Coastal Plain and serves as the primary source of water for more than two million residents. In the Santa Fe Springs–Whittier–Norwalk area, located in the northeastern part of the basin, several sources of volatile organic compounds have been identified. The volatile organic compunds aAuthorsDaniel J. Ponti, Brian J. Wagner, Michael Land, Matthew K. LandonGroundwater quality in the Coastal Los Angeles Basin, California
The Coastal Los Angeles Basin study unit is approximately 860 square miles and consists of the Santa Monica, Hollywood, West Coast, Central, and Orange County Coastal Plain groundwater basins (California Department of Water Resources, 2003). The basins are bounded in part by faults, including the Newport-Inglewood fault zone, and are filled with Holocene-, Pleistocene-, and Pliocene-age marine andAuthorsMiranda S. Fram, Kenneth BelitzResearch to More Effectively Manage Critical Ground-Water Basins
As the regional management agency for two of the most heavily used ground-water basins in California, the Water Replenishment District of Southern California (WRD) plays a vital role in sheparding the water resources of southern Los Angeles County. WRD is using the results of the U.S. Geological Survey (USGS) studies to help more effectively manage the Central and West Coast basins in the most effAuthorsJames NicklesGround-water quality of coastal aquifer systems in the West Coast Basin, Los Angeles County, California, 1999-2002
The extensive use of ground water throughout the Central and West Coast Basins of Los Angeles County during the first half of the 20th century resulted in declining water levels, widespread seawater intrusion, and deterioration of water quality along most reaches of the coast. In order to control seawater intrusion in the West Coast Basin, freshwater is injected into a series of wells at two seawaAuthorsMichael Land, Eric G. Reichard, Steven M. Crawford, Rhett R. Everett, Mark W. Newhouse, Colin F. WilliamsGeohydrology, Geochemistry, and Ground-Water Simulation-Optimization of the Central and West Coast Basins, Los Angeles County, California
Historical ground-water development of the Central and West Coast Basins in Los Angeles County, California through the first half of the 20th century caused large water-level declines and induced seawater intrusion. Because of this, the basins were adjudicated and numerous ground-water management activities were implemented, including increased water spreading, construction of injection barriers,AuthorsEric G. Reichard, Michael Land, Steven M. Crawford, Tyler D. Johnson, Rhett R. Everett, Trayle V. Kulshan, Daniel J. Ponti, Keith L. Halford, Theodore A. Johnson, Katherine S. Paybins, Tracy NishikawaSaltwater intrusion in Los Angeles area coastal aquifers: The marine connection
No abstract available.AuthorsBrian D. Edwards, Kevin R. Evans - Partners
Below are partners associated with this project.