Jump to main content or area navigation.

Contact Us

Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

San Gabriel Valley (area 2) Baldwin Park

EPA #: CAD980818512

State: California(CA)

County: Los Angeles

City: Azusa, Baldwin Park, Irwindale, West Covina, La Puente, Industry

Congressional District: 31

Other Names:

Bulletin Board

On 10/13/17, this website will no longer be updated. Site information will be migrated to the new web page at: http://www.epa.gov/superfund/sangabrielbaldwinpark .
EPA appreciates your patience through this transition. If you have questions, please contact EPA staff listed below.


Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 09/08/83

Final Date: 05/08/84

Deleted Date:

The San Gabriel Valley Area 2 Superfund Site is one of four Superfund sites addressing groundwater contamination in the San Gabriel Valley. The four sites address multiple areas of contamination in the San Gabriel Basin aquifer, a critical source of drinking water for water-scarce Southern California. The Superfund sites include areas of soil and groundwater contamination underlying portions of the cities of Alhambra, Arcadia, Azusa, Baldwin Park, Industry, Irwindale, El Monte, La Puente, Monrovia, Rosemead, South El Monte, and West Covina. The San Gabriel Valley covers approximately 170 square miles.

Groundwater contamination was first detected in the San Gabriel Valley in 1979. Following this discovery, the California Department of Public Health (CDPH, formerly the Department of Health Services) analyzed water samples collected from water supply wells throughout the Valley to assess the extent of contamination. By 1984, 59 wells were found to be contaminated with volatile organic compounds (VOCs). In the late 1990s, perchlorate, N-nitrosodimethylamine (NDMA), and 1,4-dioxane were also discovered in the groundwater.

Despite the widespread contamination, the San Gabriel Basin aquifer continues to provide the majority of the domestic water supply for the Valley's one and one-half million residents. Water utilities in the area have continued to provide their customers with clean water by obtaining water from unaffected portions of the basin, blending contaminated water with clean water to meet drinking water standards, and installing wellhead treatment systems. EPA's Superfund projects are providing additional water supplies, by providing treated groundwater to local water utilities for distribution to homes and businesses in the Valley.

EPA's efforts at the sites began in the mid-1980s with studies needed to understand the sources, nature and extent of soil and groundwater contamination. In the 1980s and early 1990s, EPA also developed a basin-wide plan to set cleanup priorities, and led State and Federal efforts to develop the institutional framework necessary to address the contamination.

In the early 1990s, EPA divided the San Gabriel Valley into eight project areas, including the Baldwin Park area. In 1994, EPA adopted the cleanup plan for the Baldwin Park project. Between 1990 and 1997, EPA identified Potentially Responsible Parties (PRPs) at the site. In the late 1990s, PRPs engaged in negotiations with local water agencies and began initial design work on the project. After reaching a detailed agreement with seven local water agencies in March 2002, design work was completed and construction work began. Construction of the planned groundwater extraction and treatment facilities was largely completed in 2006. As of September 2016, more than $250 million has been spent to construct and operate the groundwater cleanup facilities, more than 110 billion gallons of contaminated groundwater has been treated, more than 75,000 pounds of contamination removed from the ground water, and more than 40,000 pounds of contamination removed from the soil. Additional details are provided below.

EPA conducted its first "Five-Year review" of the project in 2007 and its second "Five-Year Review" in September 2012. A third "five-year review" of the Baldwin Park remedy is underway and a report documenting its findings is expected in September 2017. Reports summarizing the findings of the 2007 and 2012 reviews are available in the "Technical Documents" section below. Comprehensive annual performance evaluation reports starting in the year 2007 are also available on-line (see Site Documents and Reports below). A draft of the most recent annual performance evaluation report (for the calendar 2016) was submitted to EPA in May 2017.

Top of page

Contaminants and Risks

Contaminated Media
  • Groundwater
  • Soil and Sludges

The Baldwin Park Operable Unit addresses multiple, commingled plumes of groundwater contamination that are over a mile in width and eight miles in length. The depth to the groundwater varies from about 150 to 350 feet, and the groundwater contamination extends from the water table to more than 1,000 feet below ground surface. The most prevalent contaminants in the groundwater are trichloroethene (TCE), perchloroethylene (PCE), carbon tetrachloride, perchlorate, and N-nitrosodimethylamine (NDMA). TCE, PCE, and carbon tetrachloride are solvents used for degreasing and cleaning; perchlorate is a component of solid-fuel rockets; and NDMA is associated with liquid-fuel rockets. Other contaminants are also present, including the chemical 1,4-dioxane, which has been used as a stabilizer in chlorinated solvents, and 1,2,3-trichloropropane. The peak contaminant concentration measured in groundwater in the Baldwin Park area is 38,000 ug/l PCE; more than 7500 times the maximum contaminant level (MCL) allowed by Federal and State laws.

Top of page

Who is Involved

This site is being addressed through Federal and State actions.

Top of page

Investigation and Cleanup Activities

The remedy at the site is large-scale groundwater extraction and treatment (i.e., "pump and treat"). Five pump and treat "sub-projects" have been built or expanded, having a combined treatment capacity of more than 30,000 gallons per minute (equivalent to 43.2 million gallons per day [MGD]). Each sub-project has multiple groundwater extraction wells and three or more water treatment processes (e.g., air stripping, granular activated carbon, ion exchange, advanced oxidation ) for removal of the contaminants from the groundwater.

Site Studies

In 1989, the California Regional Water Quality Control Board, Los Angeles Region (RWQCB), working in accordance with an EPA-State Cooperative Agreement, began to identify the sources of the groundwater contamination in the Azusa/Baldwin Park area. The RWQCB inspected more than 1,400 commercial and industrial businesses in the area and required testing of soil and/or groundwater where contamination was observed or suspected. Using the test results, historical Federal, State and local records, responses to information requests, and other investigative techniques, EPA ultimately identified 21 parties as significant contributors to the groundwater contamination. The 21 companies have been named as PRPs. Hundreds of other companies have been sent "no further action" letters to inform them that EPA does not believe that they have contributed to the groundwater contamination.

From 1990 to 1993, EPA completed the Baldwin Park Operable Unit Remedial Investigation and Feasibility Study, which included an investigation of the nature and extent of contamination in the Azusa/Irwindale/Baldwin Park area and an evaluation of cleanup options. The investigation included the compilation and analysis of sampling results from existing water supply wells, temporary reactivation and sampling of inactive water supply wells, installation of a 1,500-foot deep monitoring well, installation and sampling of more than two dozen shallow groundwater monitoring wells, development of a groundwater flow model, and preliminary discussions with local water agencies over their role in the cleanup. In 1993, EPA issued its proposed cleanup plan.

Remedy Selected

In March 1994, after review of hundreds of public comments, EPA selected a cleanup plan for the Baldwin Park area. The selected remedy, now constructed, includes four groundwater pump and treat systems capable of extracting and treating more than 26,000 gallons per minute, or 37 million gallons per day (MGD), of contaminated groundwater. The remedial objectives are to remove contaminants from the aquifer and prevent future increases in, and begin to reduce, concentrations of groundwater contaminants in the Baldwin Park area by limiting further migration of contaminated groundwater into clean and less contaminated areas or depths. The Record of Decision (ROD) specifies extraction of contaminated groundwater at the downgradient end of two subareas of contamination, at locations and rates sufficient to hydraulically contain contaminated groundwater moving through each subarea during all anticipated groundwater flow conditions. The ROD was updated by the Explanation of Significant Differences in May 1999 (see link below).

Remedy Design

In 1995, a group of PRPs began to collect data needed to design the facilities called for in EPA's cleanup plan. The group, known as the Baldwin Park Operable Unit Steering Committee, installed and sampled a network of eight 700 to 1,000 foot deep multilevel groundwater monitoring wells and further developed a detailed groundwater flow model of the area. This work was completed in 1997.

At the same time, negotiations also continued over the role of local water agencies in the cleanup.

Negotiations with the water agencies were initially focused on a proposal advocated by the Metropolitan Water District of Southern California to export the treated groundwater produced by the cleanup to Metropolitan's customers elsewhere in Southern California. Despite many studies and hearings and much lobbying on behalf of the Metropolitan Plan (termed the "Consensus Plan" by one of its supporters), the plan was not implemented.

Instead, in 1998, local support shifted to an alternative plan proposed by the Main San Gabriel Basin Watermaster (a court-appointed entity responsible for administering the water rights agreement in the San Gabriel Basin). The Watermaster Plan proposed that the treated groundwater be used locally, and that local agencies play a major role in designing, building, and operating the cleanup facilities. The Watermaster Plan followed the June 1997 discovery of another contaminant in the groundwater at potentially unsafe levels. The contaminant was perchlorate, an inorganic constituent of solid rocket fuel. Two other chemicals, N-nitrosodimethylamine (NDMA) and 1,4-dioxane, were also found in the groundwater in the Baldwin Park area after perchlorate was discovered. The originally planned treatment technologies (air stripping and/or granular activated carbon) are not capable of effectively removing perchlorate, NDMA, or 1,4-dioxane from water and, at the time, no proven perchlorate-removal technologies were available. The presence of perchlorate, NDMA, and 1,4-dioxane forced the closure of additional public water supply wells in the area, leading to renewed local interest in using the treated groundwater produced by the cleanup.

Also in 1997, EPA sent "Special Notice" letters to the 19 named PRPs to begin formal negotiations expected to result in a binding commitment by the PRPs, in the form of a Consent Decree, to design, construct, and operate the groundwater cleanup facilities. The negotiations were originally expected to conclude in late 1997, but were delayed following the discovery of perchlorate, NDMA, and 1,4-dioxane.

From 1997 to 1999, with EPA oversight, the Baldwin Park Operable Unit Steering Committee installed additional groundwater monitoring wells and carried out studies of perchlorate and NDMA removal technologies

In mid-1999, EPA resumed Consent Decree negotiations with the Potentially Responsible Parties and set a deadline for the PRPs to submit a "Good Faith Offer." In September, 11 of the 19 PRPs submitted an offer that met EPA's requirements for a "Good Faith Offer." EPA-PRP negotiations continued into early 2000, in an effort to translate the September 1999 offer into a binding commitment. The PRPs and the Main San Gabriel Basin Watermaster also continued their negotiations, with EPA as facilitator and with the help of an independent mediator, to resolve a number of issues, including the technology to be used for perchlorate removal, the number of treatment facilities to be constructed, local involvement in design, construction, and operation of the treatment facilities, and use of any public funds that may be available.

By June 2000, however, negotiations had not produced agreements between EPA and the PRPs, or between the PRPs and the Watermaster. EPA concluded that negotiations alone were unlikely to produce an agreement and, on June 30, 2000, issued a Unilateral Administrative Order ("the EPA Order") directing the 19 PRPs to complete the remedial design and make arrangements for the construction and operation of the groundwater extraction wells, treatment systems, and related cleanup facilities.

The PRPs complied with EPA's Order, but the design work required by the EPA Order was slowed by uncertainty over local involvement in the cleanup. Finally, in March 2002, after hundreds of hours of negotiations and active EPA mediation, eight PRPs and seven water agencies signed a final comprehensive agreement that specified PRP and water agency roles and allowed design work to proceed. The Baldwin Park Project Agreement (available through a link below) committed the PRPs to fund the design, construction, and operation of the groundwater extraction, treatment, and conveyance facilities needed to satisfy EPA's cleanup goals and meet local water supply needs through May 2017. A ten-year extension to the PRP-water agency agreement was approved in May 2017.

Cleanup Ongoing

The remedy has been constructed as five sub-projects, as described above under "Cleanup Approach". The first of the four sub-projects, the La Puente Valley County Water District project, was completed in 2000 and is now supplying the treated groundwater for potable use.

The second of the four sub-projects, the San Gabriel Valley Water Company B6 project, was substantially completed in 2004; and, in June 2005, began supplying potable water to residents and businesses in the area.

Construction of the third sub-project, the Valley County Water District sub-project, was completed in 2005; and, in November 2005, began supplying water to residents and businesses in the area.

Construction of the fourth sub-project, the San Gabriel Valley Water Company B5 sub-project, was substantially completed in 2006 and began supplying water to residents and businesses in the area in July 2008.

The fifth sub-project, the California Domestic Water Company subproject, was formally incorporated into the remedy in 2014. Cal Domestic is a wholesale water distribution company.

SubprojectStatus Design and Construction Cost Approx. Treatment Capacity (gallons per minute)
La Puente Valley County Water DistrictOperating since 2000$ 7 million 2500
SGVWC Plant B6Operating since 2005 $36 million 7800
Valley County Water DistrictOperating since 2006 $58 million 7800
SGVWC Plant B5Operation began 2007 $22 million 7800
California Domestic Water CoOperating 5,000 to 15,000
TOTAL:more than $123 million 25,900

Remedial Action reports describing construction of four of the five sub-projects are available by clicking on the links below under the heading "Site Documents and Reports, Technical Documents." Also available in the "Technical Documents" section are the 2007 - 2015 Annual Performance Evaluation Reports, which include a discussion of the status of the cleanup and performance monitoring activities, a series of tables and figures summarizing technical information about the cleanup, and figures showing the extent of groundwater contamination.

Groundwater contamination at the site results from the cumulative impact of decades of improper chemical handling and disposal practices. Although many of the laws regulating the handling and disposal of hazardous chemicals went into effect after 1970, historical documents demonstrate that local officials were concerned about the potential for groundwater contamination by industrial activity in the San Gabriel Valley as early as the 1950s.

          The cleanup plan requires, on average, pumping of approximately 30,000 gallons per minute of contaminated groundwater and treating it to remove contaminants. The long term cost to pump and treat this water is likely to exceed $350 million, making this groundwater cleanup project one of the largest and most expensive in the United States.
          The water treatment systems make use of a variety of processes to remove the contaminants from the groundwater: ion exchange (to remove perchlorate and nitrate); ultraviolet light and hydrogen peroxide (to remove NDMA, 1,4-dioxane, and VOCs); and air stripping and/or granular activated carbon (to remove VOCs).

          An initial pilot-scale test of a biological treatment system for perchlorate removal was completed between November 1997 and May 1998. The testing demonstrated that the treatment system, which converts the perchlorate to chloride, a non-toxic form of chlorine, could reduce the concentration of perchlorate in the groundwater to non-detectable levels. The PRPs completed a second phase of testing in 2000 to determine whether the treatment system could reliably produce water of drinking water quality. Although the results of the phase 2 testing were positive, a decision was made to use ion exchange systems, rather than the biological treatment system, for perchlorate removal. A biological treatment system is in use to provide drinking water at a water utility in Rialto, California.
          A variety of proposals were made in the 1990s for use of the water pumped to the surface and treated as part of the cleanup. Earlier plans to export the treated groundwater out of the San Gabriel Valley were replaced by plans to use much of the water locally to replace supplies lost when contamination forced the closure of water supply wells.
          The Potentially Responsible Parties are ultimately responsible for funding the design, construction, and operation of the groundwater cleanup facilities, but they have benefitted from more than $38 million in Federal grants (as of April 2011). The U.S. Bureau of Reclamation and the San Gabriel Basin Water Quality Authority are administering the Federal funds.

          In November 2007, the cleanup was featured in a segment of the History Channel show "Modern Marvels."

          The Baldwin Park project has been a multi-agency Federal, State, and local effort:
            US EPA completed the remedial investigation and feasibility study, developed and adopted the cleanup plan, identified the PRPs, ordered the PRPs to implement the remedy, and have overseen design, construction, and operation of the groundwater extraction and treatment facilities.

            The California Regional Water Quality Control Board (Los Angeles) assisted EPA in identifying PRPs and has taken the lead in directing PRPs to clean up soil contamination.

            The California State Water Resources Control Board Division of Drinking Water Programs (formerly part of the California Department of Public Health), approved the design and works with EPA to oversee the operation of the five Baldwin Park water treatment systems. Water from the treatment systems water is used as a source of drinking water.

            The Potentially Responsible Parties (PRPs) include 21 companies identified by EPA as significant contributors to the groundwater contamination. Eight of the PRPs identified by EPA signed the 2002 Baldwin Park project agreement and helped pay the costs of designing, constructing, and operating the cleanup facilities. EPA has negotiated "cash-out" settlements with the majority of the remaining PRPs to resolve their liability for the contamination. Five PRPs signed the ten-year extension to the agreement in 2017.

            The Main San Gabriel Basin Watermaster is a court-appointed entity responsible for administering the water rights agreement in the San Gabriel Basin. The Watermaster is responsible for a variety of coordination, budgeting, monitoring, and reporting tasks required by the BPOU project agreement. Local water utilities own and operate the cleanup facilities

            The San Gabriel Basin Water Quality Authority (WQA) was created by the State of California in 1993 to help coordinate the plans and activities of EPA and other Federal and State agencies responsible for cleanup of the San Gabriel Basin. The WQA signed the Baldwin Park project agreement and administers Federal funds earmarked for cleanup in the San Gabriel Valley.

Top of page

Cleanup Results to Date

Top of page

Potentially Responsible Parties

Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.




Aerojet Rocketdyne Inc (formerly Aerojet General Corporation) and Gencorp Inc.1100 W. Hollyvale Street in Azusa, CAfunding cleanup and EPA oversight costs
Huffy Corporation1120 W. Foothill Blvd. in Azusa, CAfunded cleanup and EPA oversight costs until bankruptcy
Oil & Solvent Process Co.1704 W. First Street in Azusa, CAfunding cleanup and EPA oversight costs
Winco Enterprises Inc (formerly Wynn Oil Company)1151 W. 5th Street in Azusa, CAfunding cleanup and EPA oversight costs


Azusa Gas Systems/Azusa Land Reclamation Co. 1201 W. Gladstone Street in Azusa, CAfunding cleanup and EPA oversight costs
Azusa Pipe and Tube Bending766 N. Todd Ave in Azusa, CAcashout settlement
Allegiance Healthcare Corporation (formerly Baxter Healthcare)4401 Foxdale Avenue in Irwindale, CAcashout settlement
Fairchild Holding Corporation 601 S. Vincent Avenue in Azusa, CAFunded cleanup and EPA oversight costs until bankruptcy
The Hartwell Corporation701 W. Foothill Boulevard in Azusa, CAfunding cleanup and EPA oversight costs
J. H. Mitchell and Sons Distributors, Inc.14515 Joanbridge Street in Baldwin Park, CAcashout settlement
Leach International717 North Coney Avenue in Azusa, CAcashout settlement
Lockheed-Martin Corporation1004 W. 10th Street in Azusa, CAcashout settlement
Mobil Oil Corporation1004 W. 10th Street in Azusa, CAcashout settlement
Phaostron Instruments & Electronic Company717 North Coney Avenue in Azusa, CAcashout settlement
Philip Morris USA Inc.717 North Coney Avenue in Azusa, CAcashout settlement
Reichhold Inc. (formerly Reichhold Chemicals)237 Motor Ave in Azusa, CAfunded cleanup and EPA oversight costs until bankruptcy
Rubber/ Urethanes Inc.968 W. Foothill Blvd. in Azusa, CAbankrupt
Screwmatic Inc.925 W. First Street in Azusa, CAcashout settlement
U.S. Department of Defense1100 W. Hollyvale Street in Azusa, CApast and future cost settlement
Valspar Corporation1004 W. 10th Street in Azusa, CAcashout settlement
White and White Properties145 S. Irwindale Ave and 204 S. Motor Avenue in Azusa, CAcashout settlement

Top of page

Documents and Reports

Show details for Administrative RecordsAdministrative Records
Show details for Community InvolvementCommunity Involvement
Show details for Fact SheetsFact Sheets
Show details for Legal DocumentsLegal Documents
Show details for MapsMaps
Hide details for Records of DecisionRecords of Decision
03/31/94Baldwin Park Operable Unit, Record of Decision 3/31/94
05/01/99EPA Updates Cleanup Plan for the Azusa-Baldwin Park Area - ESD (Explanation of Significant Differences)
Show details for Technical DocumentsTechnical Documents

Top of page

Community Involvement

Public Meetings:

Top of page

Public Information Repositories

The public information repositories for the site are at the following locations:

West Covina Library
1601 West Covina Parkway
West Covina, CA 91790
(626) 962-3541

Rosemead Library
8800 Valley Boulevard
Rosemead, CA 91770
(626) 573-5220

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

Top of page


EPA Site Manager
Wayne Praskins
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Viola Cooper
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
(415) 947-8701
State Contact
Sue Fears
Depatment of Toxic Substances Control
8800 Cal Center Drive
Sacramento, CA 95826
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

Top of page

Jump to main content.