Variances to water quality standards
Wastewater discharges to surface water covered under Wisconsin Pollution Discharge Elimination System (WPDES) permits may be subject to water quality-based effluent limits (WQBELs). Under certain circumstances, these WQBELs may not be attainable within the five-year permit term. According to ss. 283.15 and 283.16, Wis. Stats., the department may include a water quality standards (WQS) variance in WPDES permits to provide dischargers additional time to meet the limit, during which incremental progress is made towards meeting the WQBEL.
Variances may be approved based on one or more of the six factors listed in s. 283.15(4), Wis. Stats. and must be approved by both the DNR and EPA before being incorporated into a final WPDES permit.
More information is available regarding final decisions on variances pending EPA approval.
Variance guidance
- Development and Implementation of Water Quality Standards Variances
- Statewide phosphorus multi-discharger variance
Most variances issued by DNR are individual variances—variances issued to single facilities. To date, DNR has issued individual variances for arsenic, chloride, copper, zinc, mercury, and phosphorus to many different permittees. Each individual variance has a customized, site-specific pollutant reduction plan and goals. Use the tabs below for resources on the most frequently applied for variance pollutants.
Mercury
Mercury Variances
In November 2002, DNR began to implement an approach under the WPDES program for mercury that acknowledges the special challenges with regulating a substance that causes environmental impacts at such low levels. Section NR 106.145, Wis. Adm. Code, provides the main framework for that regulatory approach and is sometimes referred to as the Wisconsin WPDES Mercury Rule. Under this rule, permittees may be eligible for alternative mercury effluent limitations otherwise known as interim limitations (which constitutes a variance to water quality standards) under the condition that the permittee implement a pollutant minimization program (PMP).
Applying for Mercury Variances
With the application for permit reissuance, permittees applying for mercury variances need to submit;
- A completed mercury variance application
- An approvable Pollutant Minimization Program (PMP) Plan. Information on what should be included in the plan can be found in Chapter 3, Section 4.02, and Appendix B of the WQS Variance Guidance.
Mercury Variance Justification
In 1997, the Ohio Environmental Protection Agency, along with Foster Wheeler Environmental Corp. and DRI/McGraw-Hill prepared a report on the economic impacts of treatment for mercury in wastewater treatment facilities. This report has been used in the Great Lakes states to support the finding in s. 283.15(4)(f), Wis. Stats., which states that the standards, as applied to the permittee, will cause substantial and widespread adverse social and economic impacts in the area where the permittee is located. This report streamlines the variance application process because the permittee does not have to individually justify their eligibility for a mercury variance.
Additional Mercury Resource
In 2006, through funding from EPA, WDNR (in partnership with the City of Superior Wastewater Division, Recycling Connections Corporation, and the Wisconsin Mercury Reduction Committee), developed a detailed guidance document focusing on source identification and minimization for municipalities. The resulting document can be found at: Mercury Pollutant Minimization Program Guidance Manual For Municipalities.
Chloride
Chloride Variances
Many wastewater treatment facilities in Wisconsin are not able to meet the 395 mg/L chronic water quality criterion in their effluent for a variety of reasons. Variances to chloride water quality standards can be applied for that allow facilities additional time to meet the limit through creative source reduction measures. Common sources of excess chloride include inflow and infiltration to municipal sewers during snow melt, road salting practices, water softener backwash and certain other industrial processes often associated with food processing. In addition to general provisions for variances explained in s. 283.15, Wis. Stats., Wisconsin also has state code in NR 106.80 through 106.96, Wis. Adm. Code that specifically regulates chloride variances.
Applying for Chloride Variances
With the application for permit reissuance, permittees applying for chloride variances need to submit;
- A completed chloride variance application
- An approvable Source Reduction Measures (SRM) Plan. Information on what should be included in the plan can be found in Chapter 3, Section 4.01, and Appendix B of the WQS Variance Guidance.
- A completed Lime Softening Inputs worksheet found in Appendix D of the WQS Variance Guidance.
Additional Chloride Resources
- Water Softener Survey Template & Cover Letter Examples – Appendix E.1 and E.2 of WQS Variance Guidance.
- Water Softener Education and Outreach – Appendix E.3 of WQS Variance Guidance.
- Additional learning resources on transport of salt in stormwater runoff can be found on the department’s webpage at: https://dnr.wisconsin.gov/topic/Stormwater/learn_more/salt.html
- Wisconsin Salt Wise Partnership
- EPA Risk Assessment – Salt
Copper
Copper Variances
Many wastewater treatment facilities in Wisconsin, especially in the northern and northwestern regions of the state, are not able to meet the copper water quality criterion in their effluent. This is primarily because the water in these areas of the state is very soft and has a higher potential to corrode copper pipes and because copper is more toxic to aquatic life in waters with lower hardness levels. Variances to copper water quality standards can be applied for which allow facilities additional time to meet the limit through source reduction measures.
Applying for Copper Variances
With the application for permit reissuance, permittees applying for copper variances need to submit;
- A completed copper variance application.
- An approvable Source Reduction Measures (SRM) Plan. Information on what should be included in the plan can be found in Chapter 3 and Appendix B of the WQS Variance Guidance.
Phosphorus
Phosphorus Variances
Permittees that choose to pursue a phosphorus variance will need to consider not only the variety of phosphorus sources at play, but also multiple compliance options. Evaluating the current feasibility of an alternative compliance option will be an important step in determining the need for a variance. The planning documents submitted during the initial phosphorus compliance schedule may be used to help support this need. For municipal (non-industrial) entities a comprehensive facility plan would be ideal in helping to identify the overall needs of the plant, final phosphorus compliance alternatives, and potential upgrades as part of a variance.
Applying for Phosphorus Variances
With the application for permit reissuance, permittees applying for phosphorus variances need to submit;
- A completed phosphorus variance application for Industrial or Municipal dischargers.
- An approvable Pollutant Minimization Program (PMP) plan. Information on what should be included in the plan can be found in Chapter 3, 4, section 4.03 and Appendix B and F of the WQS Variance Guidance.
- Phosphorus compliance alternatives analysis.
Additional Phosphorus Resources
- Phosphorus Implementation: https://dnr.wisconsin.gov/topic/Wastewater/Phosphorus
- Phosphorus Multi-Discharger Variance: https://dnr.wisconsin.gov/topic/Wastewater/phosphorus/StatewideVariance.html
- Guidance for Implementation of Wisconsin's Phosphorus Water Quality Standards for Point Source Dischargers
- EPA Technical Assistance Webinar Series: Technical Assistance Webinar Series: Improving CWA-NPDES Permit Compliance | US EPA