Water Quality Control Plan for the Lahontan region

Water quality standards and control measures for surface and ground waters of the Lahontan Region are contained in the Water Quality Control Plan for the Lahontan Region (Basin Plan). The plan designates beneficial uses for water bodies and establishes water quality objectives, waste discharge prohibitions, and other implementation measures to protect those beneficial uses. State water quality standards also include a Nondegradation Policy. Water quality control measures include Total Maximum Daily Loads (TMDLs), which are often, but not always, adopted as Basin Plan amendments. See the Lahontan Water Board’s TMDL Program web page for further information.

The Lahontan Basin plan took effect in 1995, replacing three earlier plans. The current edition of the plan includes fully approved sets of amendments adopted since 1995. Chapters and sections of the plan are available in separate files to facilitate downloading.

In addition to the state standards in the Basin Plan, federal water quality standards for certain toxic pollutants apply to surface waters within California, including the Lahontan Region. These standards are contained in the National Toxics Rule (40 CFR 131.36) and the California Toxics Rule (40 CFR 131.37). The California State Water Resources Control Board (SWRCB) has adopted a statewide implementation policy for the federal toxics standards, including summary tables listing the standards themselves. The federal standards have not yet been physically incorporated into the Basin Plan.

The National Toxics Rule and California Toxics Rule standards differ from federal water quality criteria in that they are enforceable. Federal criteria are non-enforceable, science-based thresholds that can be used in development of enforceable state water quality standards.

For the latest information on this water quality control plan, including any amendments, click here.