Water Quality Standards, Plans and Policies

Surface Water and Groundwater   |   Drinking Water   |   Bottled Water and Vended Water  

Surface Water and Groundwater

Water Quality Standards

Pursuant to the Federal Clean Water Act, water quality standards are "provisions of State or Federal law which consist of a designated use or uses for the waters of the United States and water quality criteria for such waters based upon such uses.  Water quality standards are to protect the public health or welfare, enhance the quality of water and serve the purposes of the Act."

Water Quality Control Plans

Water Boards Pursuant to Division 7 of the California Water Code, referred to as the Porter-Cologne Water Quality Control Act, designated uses of water are called "beneficial uses" and the criteria based on those uses are called "water quality objectives."  California's water quality standards are found in the Water Quality Control Plans adopted by the State Water Resources Control Board and the nine Regional Water Quality Control Boards (California Water Boards).  Because the plans adopted by the Regional Water Boards cover one or more water basins, they are often referred to as "Basin Plans."  California’s Water Quality Control Plans must include implementation programs to achieve and maintain compliance with water quality objectives.

Where They Apply

While the Federal Clean Water Act focuses on waters of the United States, navigable surface waters and their tributaries, the term “waters of the state” under the Porter-Cologne Act is broader.  “'Waters of the state' means any surface water or groundwater, including saline waters, within the boundaries of the state."  Also included are surface waters that are not tributary to navigable waters.  California has water quality standards that apply to all of these waters.

EPAFederal Adopted Criteria

In addition to standards adopted by the California Water Boards, the U.S. Environmental Protection Agency (USEPA) has adopted water quality criteria in the California Toxics Rule that apply to California's inland surface waters, enclosed bays and estuaries.  When combined with the beneficial uses found in the Basin Plans, these criteria are also California water quality standards.

Policies for Water Quality Control

Also included within California’s system of water quality standards are the “policies for water quality control” adopted by the State Water Board and incorporated into each of the Basin Plans.  California's Water Quality Control Plans and policies for water quality control have the force and effect of regulation.

Drinking Water

Water Boards

Drinking water standards are adopted by the State Water Board pursuant to the California Safe Drinking Water Act.  They directly apply to public drinking water systems and to water delivered to customers. They are enforceable by Division of Drinking Water and local health departments.

Maximum Contaminant Levels (MCLs)

MCLs are components of the drinking water standards adopted by the State Water Board.  USEPA also adopts MCLs under the Federal Safe Drinking Water Act.  California's drinking water standards are required to be at least as stringent as those adopted by the USEPA.  Some California MCLs are more stringent than USEPA MCLs.

  • Primary MCLs are based on human health protection
  • Secondary MCLs are based on human welfare considerations (e.g., taste, odor, laundry staining)

Bottled Water and Vended Water

CDPHBottled and vended water are regulated as food by the California Department of Public Health (CDPH) Food Safety Program pursuant to the Sherman Food, Drug, and Cosmetic Law.


(updated 4/1/16)