Agriculturally Dominated Water Bodies Evaluation

Municipal and Domestic Supply (MUN) Beneficial Use Project


Via the Sources of Drinking Water Policy (88-63), the Central Valley Regional Water Quality Control Board Basin Plans (Basin Plans) designate MUN beneficial use to all water bodies unless they are specifically listed as water bodies that are not designated with MUN. The Basin Plans state that waters designated for MUN must not exceed Maximum Contaminant Levels (MCLs) for chemical constituents, pesticides, and radionuclides. While 88-63 does contain exceptions for the MUN designation, to utilize the exception, the Basin Plans require ". . . a formal Basin Plan amendment and public hearing, followed by approval of such an amendment by the State Water Board and the Office of Administrative Law."

In recent years, the Central Valley Water Board issued permits to facilities that discharged wastewater to agricultural drains, and set limits in these permits designed to protect the MUN beneficial use despite thte fact that the agricultural drains presumptively met the exception criteria in the Sources of Drinking Water Policy. The high cost of compliance for these facilities caused the Board to focus on developing a more streamlined approach for applying the exception criteria in the Sources of Drinking Water Policy, making this issue a priority in the Board's 2011 Triennial Review and the priority was reaffirmed by the Board in 2015.

Concurrently, the Central Valley Salinity Alternatives for Long Term Sustainability (CV-SALTS) initiative identified that there was a need to evaluate the way the Board regulated the MUN beneficial use in agriculturally (Ag) dominated water bodies. CV-SALTS partnered with the Board to provide funding for water quality monitoring and environmental and economic analyses for a MUN evaluation project.

A stakeholder group, including representatives from federal and state agencies, public water systems, municipalities, environmental and Ag interests, met to contribute to the development of amendments to address both the Sacramento case studies and region-wide MUN evaluation effort.

On April 16, 2015, the Central Valley Water Board adopted Resolution R5-2015-0022 amending the Water Quality Control Plan for the Sacramento River and San Joaquin River Basins to remove the MUN beneficial use in twelve constructed and/or modified water bodies in the Sacramento River Basin (Sacramento case study). The amendment was approved by the State Water Board and Office of Administrative Law (OAL) later in 2015 and the final approval was provided by U.S. Environmental Protection Agency (USEPA) on April 21, 2016.

Following the successful adoption of the Sacramento case study, the region-wide MUN evaluation project was adopted on August 10, 2017 by the Central Valley Water Board (Resolution R5-2017-0088). This basin plan amendment will establish a region-wide MUN use evaluation process in Ag dominated surface water bodies and remove the MUN beneficial use from 231 constructed or modified Ag drains in the San Luis Canal Company. The basin plan amendment is currently going through the State Water Board adoption process and will be followed with the OAL and USEPA adoption processes.

Region-wide MUN Evaluation Process Basin Plan Amendment

The State Water Resources Control Board is currently accepting comments on Amendments to Establish a Region-wide Municipal and Domestic Supply (MUN) Beneficial Use Evaluation Process in Agriculturally Dominated Surface Water Bodies and to Remove the MUN Beneficial Use From 231 Constructed or Modified Ag Drains in the San Luis Canal Company District.

State Water Board Action

Central Valley Water Board Action

10/11 August 2017 Central Valley Board Meeting

23/24 February 2017 Central Valley Board Meeting

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