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Water Quality Standards Regulations: Idaho

Presented below are water quality standards in effect for Clean Water Act (CWA) purposes for this state.

EPA is posting these standards as a convenience to users and has made a reasonable effort to assure their accuracy. Also, for each document listed under "State Standards in Effect for CWA Purposes", EPA has made a reasonable effort to identify parts of the standards that are disapproved or are otherwise not in effect for CWA purposes.

On this page:

State Standards in Effect for CWA Purposes

  • [See Water Quality Standards ]
    (Effective June 9, 2020) State regulation establishing water quality standards for surface waters of the state.  Please note that not all parts of this document are effective for Clean Water Act purposes. Refer to cover pages for more information.

Federally Proposed or Promulgated Standards

Selected Actions and Correspondence

Recent actions along with supporting documents are provided below for reference.

June 9, 2020 - EPA Review and Action on Idaho’s Water Quality Standards, Seasonal Cold Water Criteria
December 16, 2019 - EPA Review and Action on Idaho’s New and Revised Water Quality Standards, Mixing Zone Policy
November 21, 2019 - EPA Review and Action on Idaho's Revised Site-Specific Criteria for Temperature for the Hells Canyon Reach of the Snake River
July 9, 2019 - EPA partial approval and disapproval of Idaho’s Selenium Aquatic Life Criteria
May 2, 2019 - EPA approval Idaho’s revised Aquatic Life Criteria for Copper using the Biotic Ligand Model
April 4, 2019 - EPA approval of Idaho's updated human health criteria.

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