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Why we regulate
Learn what types of wastewater discharges are regulated and how
Plan review
The DNR reviews plans for municipal and industrial wastewater treatment plant construction
Discharge permits
Wastewater discharges to surface or groundwaters
Contact information
For information on variances to water quality standards contact:
Jason Knutson
Wastewater Section Chief
Water Quality Bureau

Variances to water quality standards

Facility-specific variances to water quality standards, referred to as variances, must be approved by both DNR and USEPA. Variances may be given on a facility-specific basis for the length of a Wisconsin Pollutant Discharge Elimination System(WPDES) permit term.

photo by Adam Freihoefer

A variance is appropriate when a facility is unable to meet the water quality standard for a given pollutant, and a solution for treatment or source reduction is not readily apparent at this time. Variances may be approved based on one or more of the six factors listed in s. 283.15(4), Wis. Stats., which reads:

The secretary shall approve all or part of a requested variance, or modify and approve a requested variance if the permittee demonstrates, by the greater weight of the credible evidence, that attaining the water quality standard is not feasible because:

  1. Naturally occurring pollutant concentrations prevent the attainment of the standard;
  2. Natural, ephemeral, intermittent or low flow conditions or water levels prevent the attainment of the standard, unless these conditions may be compensated for by the discharge of sufficient volume of effluent discharges without violating water conservation requirements;
  3. Human caused conditions or sources of pollution prevent the attainment of the standard and cannot be remedied or would cause more environmental damage to correct than to leave in place;
  4. Dams, diversions or other types of hydrologic modifications preclude the attainment of the standard, and it is not feasible to restore the water body to its original condition or to operate such modification in a way that would result in the attainment of the standard;
  5. Physical conditions related to the natural features of the water body, such as the lack of proper substrate, cover, flow, depth, pools, riffles, and the like, unrelated to water quality, preclude attainment of aquatic life protection uses; or
  6. The standard, as applied to the permittee, will cause substantial and widespread adverse social and economic impacts in the area where the permittee is located.

Variance guidance

Guidance

Guidance is currently being developed to assist permittees on the following issues regarding variances. New guidance documents will be available here as they are developed.

  • Mercury - Guidance on mercury variances and pollutant minimization plans
  • Chloride - Guidance on chloride variances and source reduction measures
  • Copper - Guidance on copper variances and source reduction measures
  • Arsenic - Guidance on arsenic variances and discharge mitigation
  • Phosphorus - Guidance on phosphorus variances and source reduction measures
  • Economics - Guidance for municipalities and industries on proving substantial and widespread social and economic impacts

Mercury

Mercury variances
Water quality standards for mercury in Wisconsin are set based on the wildlife criterion. This criterion represents the concentration of mercury, which if not exceeded, protects Wisconsin’s wildlife from adverse effects resulting from ingestion of surface waters of the state and from ingestion of aquatic organisms taken from surface waters of the state. The water quality criterion for mercury in Wisconsin is 1.3 ng/L.

Many wastewater treatment facilities in Wisconsin are not able to meet the 1.3 ng/L criterion in their effluent for a variety of reasons. Variances to mercury water quality standards can be applied for which allow facilities additional time to meet the limit through creative pollutant minimization strategies. Common mercury sources include dental and medical facilities, laboratories, and household products. Permittees with approved variances are expected to minimize the sources of the variance pollutant in their discharge, where possible, and track and report on their progress toward achieving water quality criteria. View guidance on Pollutant Minimization Plans and Source Reduction Measures [PDF] in addition to worksheets to help track progress. In addition to general provisions for variances explained in s. 283.15, Wis. Stats.[exit DNR], Wisconsin also has state code in NR 106.145[exit DNR] that specifically regulates mercury variances.

Applying for mercury variances
Section 283.15, Wis. Stats. describes timelines for applying for variances and the required information to be included in variance applications. Permittees applying for mercury variances need to submit a completed mercury variance application [PDF] to Department staff. Applications for reissued variances should also include the attachment to industrial variance application [PDF] or attachment to municipal variance application [PDF].

Mercury variance justification
In 1997, the Ohio Environmental Protection Agency, along with Foster Wheeler Environmental Corporation and DRI/McGraw-Hill prepared a report [PDF] 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.

Mercury variance guidance
Wisconsin DNR partnered with the Division of Public Works in the City of Superior and Recycling Connections Corporation to create a document entitled Mercury Pollutant Minimization Program Guidance Manual for Municipalities [PDF] to help permittees in the variance application process. This document provides some background information on mercury and instructions on how to fill out variance forms, as well as case studies and examples for permittees to follow. It should be noted, however, that this report was intended to aid permittees through their first mercury variance, and that reissued variances may have additional requirements. The Department is currently developing guidance to assist permittees with reissued variances.

Chloride

Chloride variances
Water quality standards for chloride in Wisconsin are set based on aquatic life toxicity. The water quality criteria for chloride in Wisconsin are 395 mg/L (chronic) and 757 mg/L (acute).

  • Chronic toxicity — the ability of a substance to cause an adverse effect in an organism which results from exposure to the substance for a time period representing that substantial portion of the natural life expectance of that organism
  • Acute toxicity — the ability of a substance to cause mortality or an adverse effect in an organism which results from a single or short-term exposure to the substance.

Many wastewater treatment facilities in Wisconsin are not able to meet the 395 mg/L chronic criterion in their effluent for a variety of reasons. Variances to chloride water quality standards can be applied for which 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. View guidance on Pollutant Minimization Plans and Source Reduction Measures [PDF] in addition to worksheets to help track progress. 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,[exit DNR] that specifically regulates chloride variances.

Applying for chloride variances
Section 283.15, Wis. Stats.[exit DNR] specifies timelines for applying for variances and the required information to be included in variance applications. Permittees applying for chloride variances need to submit a completed chloride variance application [PDF] to Department staff. Applications for reissued variances should also include the attachment to variance application [PDF].

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 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 creative source reduction measures, if any are feasible. View guidance on Pollutant Minimization Plans and Source Reduction Measures [PDF] in addition to worksheets to help track progress.

Applying for copper variances
Section 283.15, Wis. Stats.[exit DNR] specifies timelines for applying for variances and the required information to be included in variance applications. Permittees applying for copper variances need to submit a completed copper variance application to Department staff. Applications for reissued variances should also include the attachment to variance application [PDF].

Copper variance guidance
Guidance is currently being updated for copper variances. Please see the Department’s copper primer [PDF] for additional information about copper sources and potential treatment options.

Economics

Economics of variances
Section 283.15(4), Wis. Stats. describes the reasons that a variance may be approved and included in a WPDES permit. The most commonly utilized rationale for approving variances is s. 283.15(4)(f), Wis. Stats., which states that the standard, as applied to the permittee, will cause substantial and widespread adverse social and economic impacts in the area where the permittee is located.

Typically, a municipality applying for a variance needs to demonstrate that the treatment alternatives required to treat for the pollutant in question would raise the sewer user rates of a municipality to greater than 2% of the Median Household Income. EPA guidance would then conclude that the community would experience substantial and widespread adverse social and economic impact and would be eligible for a variance under s. 283.15(4)(f), Wis. Stats. Information about the Median Household Income of a given community can be found at the US Census Bureau[exit DNR] website. Industrial permittees applying for variances will need to supply additional information such as overall size of the company and the effect the additional cost of treatment will have on the company and the community in which it resides.

Economic guidance
EPA has prepared a guidance document titled Interim Economic Guidance for Water Quality Standards [PDF] which the Department encourages permittees to review to assist them in justifying the need for a variance under s. 283.15(4)(f), Wis. Stats. Visit the EPA website for additional information on this EPA guidance document[exit DNR].

Last revised: Monday May 15 2017