Stepping Up the Secondary: Impacts of Increasingly Stringent Treated Wastewater Ammonia Discharge Limits on Small Montana Communities

Abstract

The question of waste disposal has always been an inherent problem of urbanized environments. The passage of the Federal Water Pollution Control Act, specifically the 1972 Amendments known as the Clean Water Act (CWA), legislated secondary treatment of all municipal wastewater and provided funds to construct or upgrade facilities. Since the passage of the CWA and the implementation of secondary wastewater treatment facilities, the federal Environmental Protection Agency (EPA) and the Montana Department of Environmental Quality (MDEQ) have developed and enforced increasingly stringent effluent limitations to protect surface waters and human health. Today small Montana communities face a critical juncture. The mechanical components of their 30 to 40 year old wastewater treatment facilities have reached the end of their useful design lives and the treatment capabilities of the existing facilities can no longer meet stringent effluent limits, especially for ammonia. Many small Montana communities have been affected; this thesis analyzes the impacts on three communities. The City of Conrad is addressing this issue through the construction of a mechanical treatment plant. The City of Glasgow is utilizing an advanced covered lagoon treatment system. However, as demonstrated by the City of Deer Lodge, the future of treated effluent limits is also at a critical juncture as the EPA and MDEQ take a holistic watershed approach to effluent limits by considering both point and non-point sources of pollution through watershed total maximum daily loads (TMDLs).