Surface Water Quality Standards

Wyoming’s surface water quality standards include designated uses, water quality criteria, and antidegradation provisions to protect and restore Wyoming’s surface waters for present and future generations. The standards are developed to be consistent with the Wyoming Environmental Quality Act and federal Clean Water Act using scientific principles, data and supporting information, and public input.

Current Standards

Wyoming’s Surface Water Quality Standards are included in Chapter 1 of the Water Quality Rules and Regulations and were last updated on September 24, 2013. Implementation Policies for Antidegradation, Mixing Zones and Dilution Allowances, and Use Attainability Analysis also became effective September 24, 2013.

Surface water designated uses are assigned to Wyoming’s surface waters through a hierarchical classification system. To determine the class and designated uses that apply to particular surface waters in Wyoming, use the Wyoming Surface Water Classification List and the Recreation Designated Uses Web Map. Changes to designated uses and site-specific water quality criteria are made through a formal process can be viewed here.

The salinity standards adopted through the Colorado River Basin Salinity Control Forum (Forum) also apply to Wyoming surface waters within the Colorado River Basin. The Forum's most recent triennial review can be found at the following website:

Rulemaking to Allow for Discharger Specific Variances

The Water Quality Division initiated a revision of the Water Quality Rules and Regulations, Chapter 1, in February 2017. The proposed rule outlines a process whereby the Administrator of the Water Quality Division, after considering public input, may grant a temporary modification to a designated use and water quality criteria, called a discharger specific variance. See Proposed Rules and Regulations for comment opportunities associated with this rulemaking and sign up here to receive updates from the Water Quality Division, including comment opportunities.

Nutrient Pollution

For more information on nutrient pollution and Wyoming’s efforts to address nutrient pollution, click here.