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. The standards are developed to be consistent with the Wyoming Environmental Quality Act and federal Clean Water Act using scientific principles, available data and supporting information, as well as 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 April 24, 2018. Implementation Policies for Antidegradation, Mixing Zones and Dilution Allowances, and Use Attainability Analysis were last revised on September 24, 2013. An Interim Policy on Establishing Effluent Limits for Permitted Point Source Discharges to Class 1 Water Tributaries was developed in 2007.

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 and 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:

Potential Changes to Standards: Triennial Review

The federal Clean Water Act requires states to review their surface water quality standards at least every three years, known as a triennial review. Wyoming’s surface water quality standards are currently under review; for more information, click here.

Nutrient Pollution

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


Program Resources

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