Why is DEQ proposing this rule now?

Frequently Asked Questions

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.