Drinking Water Source Assessment and Protection (DWSAP) Program

State Board’s Division of Drinking Water (DDW) established the California DWSAP Program to provide information to communities that wish to develop local programs to protect their sources of drinking water. The DWSAP Program has two primary elements: Drinking Water Source Assessment and Source Protection.

As part of permitting new sources, water systems are required a source water assessment for the proposed site.  Water systems can find resources below for completing a source water assessment.

Persons interested in completed copy of source water assessments may contact the water systems or the local DDW district offices.

Source Assessment Resource for Water Systems

For more, go to:

Drinking Water Source Assessment

The drinking water source assessment is the first step in the development of a complete drinking water source protection program. The assessment includes: A delineation of the area around a drinking water source through which contaminants might move and reach that drinking water supply; an inventory of possible contaminating activities (PCAs) that might lead to the release of microbiological or chemical contaminants within the delineated area; and a determination of the PCAs to which the drinking water source is most vulnerable.

The California DWSAP Program Document (PDF), including the oversized Table 5-1, describes procedures for conducting drinking water source assessments. It conveys the goals and objectives that we seek to accomplish with the DWSAP program, along with methods that are technically appropriate and easily understood.

Since 1997, DDW, with the assistance of others—34 counties, the California Rural Water Association, and more than 500 water systems—completed assessments for nearly all the public drinking water sources in the state.  By December 31, 2004, California completed assessments for 16,152 drinking water sources (from 7,543 public water systems).

Summaries of assessments are available for viewing by contacting the water system or the local DDW district offices.  Note that assessment summaries may not be available for some sources. This is because:

  • The assessment has not been completed.
  • The source is not active. It may be out of service, or new and not yet in service.
  • The assessment was not submitted electronically (under development).


The 1996 federal Safe Drinking Water Act amendments require each state to develop and implement a Source Water Assessment Program. Section 116762.60 of the State Board to develop and implement a program to protect sources of drinking water, specifying that the program must include both a source water assessment program and a wellhead protection program. In response to both of these legal mandates, DDW developed the DWSAP Program.

California's DWSAP Program addresses both groundwater and surface water sources. The groundwater portion of the DWSAP Program serves as the states wellhead protection program. In developing the surface water components of the DWSAP Program, DDW integrated the existing requirements for watershed sanitary surveys.

At the start of the program, there were around 15,000 active drinking water sources in California. The resources available for the assessments were approximately $7.5 million from the federal Drinking Water State Revolving Fund, or roughly a few hundred dollars per source. Although DDW was responsible for performing these assessments, some public water systems performed their own assessments conducted them in conformance with the DDW procedures.

DDW submitted the DWSAP Program Document (PDF, 1.6MB ) in January 1999. US EPA approved the DWSAP as California's wellhead protection program in January 1999. In November 1999, US EPA gave final approval of the DWSAP Program as California's sources water assessment and protection program. DDW was responsible for the completion of all assessments by May 2003.  Water systems that planned to conduct their own assessments were required to submit their final assessments to DDW no later than December 31, 2002.

In 1997-1998, as the DWSAP Program was being developed, DDW published various drafts of the DWSAP Program Document, and gave numerous presentations about the Program to inform the public and to obtain public input. During this period, DDW met with advisory groups formed to help develop the DWSAP Program.  DDW also developed an electronic (TurboSWAP) way to prepare and submit source water assessment reports.  DDW is in the process in developing a TurboSWAP replacement.