Bill seeks to clarify groundwater oversight in the Central Basin


A proposed law designed to keep water bills from skyrocketing has passed a state Senate committee, but opponents vow to fight the measure they say is a “political power grab.”

Senate Bill 1386, authored by Sen. Alan Lowenthal, D-Long Beach, would remove barriers to storing groundwater in the Central Basin and would allow for underground water reserves to protect against high rates in dry periods. Area cities and water agencies have been embroiled in legal battles over how and by whom the water should be stored.

“Without this bill, continued efforts by the Central Basin Municipal Water District will lead to more and more lawsuits, create greater and greater legal bills, and result in higher rates for our region,” said Lowenthal in a written statement following the committee vote.

“Enough is enough,” the senator added. “It’s time we move forward as a region, and I believe SB 1386 provides us with the path to resolution.”



WRD designated the Groundwater Monitoring Entity for the Central Basin


WRD’s comprehensive network of monitoring wells in the Central Basin to be incorporated into statewide groundwater monitoring program.

The California Department of Water Resources has officially designated the Water Replenishment District of Southern California as the Groundwater Level Monitoring Entity for Central Basin and West Coast sub-basin under the California Statewide Groundwater Elevation Monitoring (CASGEM) Program. The CASGEM program is a statewide groundwater monitoring program that will make groundwater information readily and widely available. WRD has established a large network of monitoring wells in the Central Basin and regularly analyses both water levels and water quality in the area.

“WRD is pleased that DWR recognizes the expertise and experience of its staff to provide the groundwater information,” stated WRD Board President Sergio Calderon. “For over 50 years, the District has prepared and published an annual Engineering Survey and Report which contains current and historical data on groundwater production, the annual and accumulated overdraft, groundwater levels, and detailed information on groundwater conditions. Additionally, WRD’s Hydrogeology Group prepares and publishes an annual Regional Groundwater Monitoring Report, first issued in1972, which relies on the District’s nearly 300 depth-specific monitoring wells at over 50 different locations.”

“WRD also appreciates support by the Central Basin Water Association and the West Basin Water Association that the District be named as the area’s groundwater monitoring entity,” commented WRD GM Robb Whitaker. “The Water Associations are important stakeholders and the District works closely with them to ensure that the Central and West Coast groundwater basins are protected.”


What is the Central Basin?


From the California Department of Water Resources

Basin Boundaries and Hydrology

The Central Subbasin occupies a large portion of the southeastern part of the Coastal Plain of Los Angeles Groundwater Basin. This subbasin is commonly referred to as the “Central Basin” and is bounded on the north by a surface divide called the La Brea high, and on the northeast and east by emergent less permeable Tertiary rocks of the Elysian, Repetto, Merced and Puente Hills. The southeast boundary between Central Basin and Orange County Groundwater Basin roughly follows Coyote Creek, which is a regional drainage province boundary. The southwest boundary is formed by the Newport Inglewood fault system and the associated folded rocks of the Newport Inglewood uplift. The Los Angeles and San Gabriel Rivers drain inland basins and pass across the surface of the Central Basin on their way to the Pacific Ocean. Average precipitation throughout the subbasin ranges from 11 to 13 inches with an average of around 12 inches.

Hydrogeologic Information

Water Bearing Formations

Throughout the Central Basin, groundwater occurs in Holocene and Pleistocene age sediments at relatively shallow depths. The Central Basin is historically divided into forebay and pressure areas. The Los Angeles forebay is located in the northern part of the Central Basin where the Los Angeles River enters the Central Basin through the Los Angeles Narrows from the San Fernando Groundwater Basin. The Montebello forebay extends southward from the Whittier Narrows where the San Gabriel River encounters the Central Basin and is the most important area of recharge in the subbasin. Both forebays have unconfined groundwater conditions and relatively interconnected aquifers that extend up to 1,600 feet deep to provide recharge to the aquifer system of this subbasin (DWR 1961). The Whittier area extends from the Puente Hills south and southwest to the axis of the Santa Fe Springs-Coyote Hills uplift and contains up to 1,000 feet of freshwater-bearing sediments. The Central Basin pressure area is the largest of the four divisions, and contains many aquifers of permeable sands and gravels separated by semi-permeable to impermeable sandy clay to clay, that extend to about 2,200 feet below the surface (DWR 1961). The estimated average specific yield of these sediments is around 18 percent. Throughout much of the subbasin, the aquifers are confined, but areas with semi- permeable aquicludes allow some interaction between the aquifers (DWR 1961).

The main productive freshwater-bearing sediments are contained within Holocene alluvium and the Pleistocene Lakewood and San Pedro Formations (DWR 1961). Throughout most of the subbasin, the near surface Bellflower aquiclude restricts vertical percolation into the Holocene age Gaspur aquifer and other underlying aquifers, and creates local semi-perched groundwater conditions. The main additional productive aquifers in the subbasin are the Gardena and Gage aquifers within the Lakewood Formation and the Silverado, Lynwood and Sunnyside aquifers within the San Pedro Formation (DWR 1961). Specific yield of deposits in this subbasin range up to 23 percent in the Montebello forebay, 29 percent in the Los Angeles forebay, and 37 percent in the Central Basin pressure area (DWR 1961).

Historically, groundwater flow in the Central Basin has been from recharge areas in the northeast part of the subbasin, toward the Pacific Ocean on the southwest. However, pumping has lowered the water level in the Central Basin and water levels in some aquifers are about equal on both sides of the Newport-Inglewood uplift, decreasing subsurface outflow to the West Coast Subbasin (DWR 1961).




Central Basin Water & Groundwater Protection With “The Slurps”


Squirt Graphic


New Educational Water Conservation Animation Makes Saving Water Fun

The Water Replenishment District (WRD), the groundwater management agency for the Central Groundwater Basin, announced today the launch of its new animated Squirt educational water conservation series

Squirt is the latest WRD water hero to aid in the District’s groundwater protection efforts in the Central Water Basin and West Coast Water Basin.

“We are enthused about the new Squirt series” said WRD Board President Sergio Calderon. “This animation will allow us to share our mission, vision and story with children in a creative way, and will help us continue to keep the public informed, educated and excited about what we are doing to protect our most precious treasure, groundwater.”

Throughout the year, WRD will release new episodes as Squirt looks out for groundwater contamination and provides tips for more efficient water use. Videos, printed materials and other educational materials will be made available for use in schools located in WRD’s Service Area.

Squirt is part of WRD’s water conservation outreach program that will help Californians meet the statewide mandate to reduce water consumption 20 percent by 2020.

The Water Replenishment District of Southern California is the regional groundwater management agency that protects and preserves the quantity and quality of groundwater for two of the most utilized urban basins in the State of California, with a service area that is home to over ten percent of California’s population residing in 43 cities in southern Los Angeles County with a publicly elected Board of Directors including Willard H. Murray, Jr., Robert Katherman, Lillian Kawasaki, Sergio Calderon, and Albert Robles.

For more information about the Water Replenishment District please visit


Groundwater, Oil and Gas: A mixture of Valuable Natural Resources in the Central and West Coast Basins


The Central and West Coast Basins (CWCB) in coastal Los Angeles County have been a valuable source of fresh groundwater for over 100 years. Nearly 400 wells are currently pumping groundwater out of sand and gravel aquifers of Holocene and Pleistocene age that range in depth from about 100 feet to 1,500 feet for potable, agri- cultural, and commercial use. Because the CWCB are in overdraft, WRD uses recycled water and imported river water to replace the extracted groundwater to help ensure the current and future usability of the basins as a local supply of high qual- ity, reliable, and cost effective water.

Separated from and beneath these freshwater aquifers in the Pliocene- age Repetto and Lower Fernando Formations and Miocene-age Puente Formation are extensive oil and natural gas deposits that have also been extracted for over 100 years. These petroleum reservoirs range in depth from about 2,500 feet to 10,000 feet or more, and are sepa- rated from the overlying freshwater aquifers by layers of low permeabil- ity siltstone and shale

Oil and Gas Formation

Oil and natural gas are fossil fuels formed from the burial, decay and alteration of organic matter – not from the dinosaurs but instead from the nu- merous marine microorganisms that inhabit the world’s oceans. When these carbon- and hydrogen-rich microor- ganisms die, settle to the seafloor and are covered by large amounts of sediment, changes occur. Pressure from the weight of the overlying sediments, high temperatures due to the depth of deposition, and extensive time in the ground all allow chemical reactions to occur that convert the large, complex organic molecules into simpler, lighter hydrocarbons to create oil, gas, and other petroleum products such as tar and asphalt.



Geohydrologic Study of the Central and West Coast Basins of Los Angeles County



Since 1995, the U.S. Geological Survey (USGS), in cooperation with the Water Replenishment District of Southern California (WRDSC), has conducted an intensive study of the geohydrology and   geochemistry of the Central and West Coast Basins of Los Angeles County. The major thrusts of the study over the past 12 years have been: 1) drilling and collecting detailed data from monitoring wells throughout the basins, 2) conducting regional geohydrologic and geochemical analyses of the basins, 3) developing and applying a computer simulation model of regional ground-water flow.