The Multiple Discharger Variance (MDV) is a variance from the total ammonia nitrogen water quality standard. It allows multiple communities to be covered under one variance. In a permit incorporating the MDV, typical ammonia effluent limits that are based on the water quality standard would be replaced with the highest attainable conditions of the current treatment facility during the term of the variance. This provides communities with the time and flexibility to make water quality improvements in a cost-effective manner.

The Multiple Discharger Variance Framework: Total Ammonia Nitrogen CWC-MDV-1-17 has been incorporated into Missouri’s Water Quality Standards at 10 CSR 20-7.031(12). It was approved by EPA on Dec. 26, 2019 making the 20-year term of the MDV from Dec. 26, 2019 through Dec. 25, 2039.

MDV Resources

Permits Issued under the Terms and Conditions of the MDV

None at this time.

MDV Framework Development

Multiple Discharger Variance: Total Ammonia Nitrogen, Sept. 15, 2017
Public Notice May 6, 2016 through June 6, 2016
Public Notice March 1, 2017 through March 30, 2017

Public Comments

June 30, 2017- Responses to Comments
Sept. 1, 2017- Responses to Comments
Sept. 15, 2017- Responses to Comments