Water Quality Standards Variance
A water quality variance is a time-limited designated use and criterion change for a specific pollutant, allowing deviation from meeting a water quality-based effluent limit (WQBEL) for a specific discharger. Federal and state regulations allow the flexibility to adopt a variance based upon one of the six use attainability factors outlined in 40 CFR §131.10(g)(6) or actions necessary to facilitate lake, wetland, or stream restoration through dam removal or other significant reconfiguration activities preclude attainment of the designated use and criterion while actions are being implemented. A variance serves as the applicable water quality standard for implementing the National Pollution Discharge Elimination System / Missouri State Operating Permit (NPDES/MSOP) permit program or when issuing Clean Water Act 401 certifications. It is important to consider that the currently attained ambient water quality shall not be adversely affected during the term of the variance.
No Water Quality Standards Variances Currently on Public Notice
Water Quality Standards Variances in Progress
Multiple Discharger Variance Framework Documents, Public Comments and Responses to Comments
Missouri Department of Natural Resources, Missouri Multiple Discharger Variance from the Water Quality Standards of Total Ammonia Nitrogen, Sept. 15, 2017
Memo - Multiple Discharger Variance Framework: CWC-MDV-1-17, Sept. 15, 2017
40 CFR Part 131.14: EPA’s regulations for water quality standards variances.
Checklist For Evaluating State Submission Of Discharger-Specific Water Quality Standards Variances (PDF): EPA’s checklist for determining if a state has met all of the regulatory requirements for a water quality standards variance applicable to specific dischargers.
Discharger-specific Variances on a Broader Scale: Developing Credible Rationales for Variances that Apply to Multiple Dischargers (PDF): EPA’s Frequently Asked Questions for water quality standards variances applicable to multiple dischargers.
Economic Guidance for Water Quality Standards: EPA’s guidance for conducting economic analyses for changes to water quality standards (including water quality standards variances). Use the various spreadsheet tools on this page for additional help.
State-Specific Water Quality Standards Effective under the Clean Water Act (CWA): State, territorial, and authorized tribal water quality standards that EPA has approved or are otherwise in effect for Clean Water Act purposes.
Water Quality Standard Variance