A Primer on Water Quality Trading

The Environmental Protection Agency (EPA) issued the first Water Quality Trading Policy in 2003, designed to guide the development of responsible programs to reduce pollution in our nation’s waterways.

WQT allows municipalities and wastewater permittees to offset the amount of phosphorus discharged by their wastewater treatment facility (in excess of the applicable WQBEL) by implementing trades with non-point dischargers or instituting best management practices (BMPs) within the watershed. The offsets generated come in the form of credits, a unit of pollutant reduction measured in a per-pound equivalent.

In order to promote the potential for improving water quality, an uncertainty factor known as a “trade ratio” is applied to the amount of phosphorus that must be offset by the discharger.

In the case of Brodhead, the City would need to conservatively generate 238 pounds of phosphorus credit per year in order to comply with the established WQBEL and compliance goals, factoring in population and industrial growth over the next 20 years.

Utilizing the WQT program, the City is on track to generate at least 390 pounds of total credit per year at an average trade ratio of 2.8:1. (1,090 pounds removed = 390 pounds of credit).