Evaluating the Role of Point Sources Informs Statewide Nutrient Control Policy

Abstract

An evaluation of the costs, rate impacts, and environmental impacts of upgrading POTWs in the State of Utah to four levels of nutrient control allowed a variety of POTW nutrient control policies to be evaluated. POTW unit upgrade costs and rate impacts indicated that costs would be within a defined range for many POTWs, especially those with design capacities greater than about 40,000 m 3 /day (~10 mgd). However, unit costs were significantly higher for some POTWs with lower design capacities, and nutrient upgrades to the most stringent levels would not be affordable for some communities representing about 15 percent of the service population. Methods for addressing the resulting equity issues include a hardship grants program and/or regulation based on a trading scheme. Analysis demonstrated that trading offers further advantages, including cost efficiency, flexibility to accommodate further nutrient reductions and population growth, and greater ability to interface with urban and rural non-point nutrient control. Consideration of "early movers" is desirable for any POTW nutrient control policy selected. The potential for future, more stringent effluent discharge requirements should be considered during the planning and design of POTW upgrades and expansions.