Surface Water Quality Standards

Frequently Asked Questions

The Wyoming Department of Environmental Quality (DEQ) is adding language to the Water Quality Rules and Regulations, Chapter 1, Wyoming Surface Water Quality Standards, to allow the Water Quality Administrator to grant temporary modifications to the water quality standards in circumstances where meeting a water quality based effluent limit for ammonia and/or nutrients would result in substantial and widespread social and economic impacts (economic hardship) in the area of the discharge.

Yes, variances are allowed under the Clean Water Act. USEPA has recommended that states use variances as one tool to facilitate adoption of increasingly stringent water quality criteria for pollutants such as nutrients and ammonia. USEPA revised the water quality standards regulations in August 2015 to include additional details on the use of variances (see 40 CFR § 131.14). USEPA also has a checklist for evaluating state submissions of discharger-specific variances.

The public will be provided drafts of each variance prior to an Administrator’s determination. The public will be able to provide comments in writing or at public hearing on the proposed variance. The public will also be provided an opportunity to comment on each reevaluation of the variance. Reevaluations must occur at least every five years.

DEQ is aware of at least one small municipality in the state that is looking at significant and costly upgrades to their wastewater treatment system to meet an ammonia effluent limit derived from a TMDL. DEQ is also considering adopting the United States Environmental Protection Agency’s (USEPA) 2013 recommended aquatic life criteria for ammonia. The 2013 recommended chronic ammonia criteria is approximately half of Wyoming’s current chronic ammonia criteria. The revised criteria will likely increase the number of wastewater treatment systems in the state that may have difficulty meeting ammonia effluent limits because many wastewater treatment systems were not designed to treat to low levels of ammonia. DEQ is also aware of some surface waters in the state that are impacted by nutrient (total phosphorus and/or total nitrogen) pollution and that most wastewater facilities were not designed for nutrient removal. These facilities may have difficulty meeting nutrient effluent limits.

As part of an economic hardship demonstration, permittees will be required to identify costs associated with pollutant removal techniques. DEQ and the permittee would evaluate the permittees economic situation and the pollutant removal techniques to determine what affordable pollutant control technique will provide the best effluent quality.

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