In late 2010, as part of a three-rule package, the Wisconsin Department of Natural Resources developed innovative administrative rules for including effluent limits in point source permits based on numeric phosphorus water quality standards criteria. The other two rules were numeric phosphorus water quality standards criteria and enforceable nonpoint source performance standards for controlling phosphorus losses from farmlands. Recognizing that for the majority of Wisconsin’s lakes and streams agricultural nonpoint sources are the dominant contributor of phosphorus, the point source administrative rules included not only water quality trading as an implementation alternative, but an innovative watershed adaptive management option. In this innovative option, dischargers may work with watershed partners to develop and implement watershed plans that control phosphorus reaching the streams and lakes at a far lower cost.
Implementation of the watershed project may over time result in a less stringent effluent limit for the facility due to improved upstream water quality. Subsequent to passage of the rules, the Department developed a number of implementation guides and tools, including the Pollutant-load Ratio Estimation Tool (PRESTO), as a means to determine eligibility for the watershed adaptive management option. PRESTO estimates the phosphorus contribution from the entire watershed, including nonpoint sources, the particular point source, and all point sources upstream. Without accepted tools, both permittees and permit staff would be faced with an increased workload.
Results to Date:
Development and implementation of both point source and nonpoint source rules should result in a more comprehensive and cost-effective attainment of phosphorus water quality standards. As one of the first steps, where necessary and appropriate, Wisconsin Pollutant Discharge Elimination System permits are being issued with compliance schedules allowing permittees to consider and select compliance options in the first permit term. Over the next decade, the trading and the watershed adaptive management options will save dischargers hundreds of millions of dollars in compliance costs.
Director, Water Quality Bureau
Wisconsin Department of Natural Resources