The U.S. Environmental Protection Agency recently proposed to jettison a numeric turbidity limitation that it had previously established for stormwater discharges from construction sites. Under a proposed rule issued in early April, the EPA would instead rely exclusively on best management practices, or BMPs, to minimize the pollutants that stormwater carries away from these sites and delivers to nearby waterways. While the agency retreat marks a victory for the industry groups that challenged the imposition of the numeric limitation, there are reasons to believe that this victory could be short-lived.
The Clean Water Act prohibits certain discharges of pollutants to waterways without a National Pollutant Discharge Elimination System (NPDES) permit. Among other things, NPDES permits often contain numeric limitations that restrict the levels of pollutants that may be discharged to navigable waters. The EPA derives some of these limitations from national technology-based performance standards for categories of industries. These standards, which the act requires the EPA to develop and update periodically, are meant to represent the greatest pollutant reductions that are economically achievable for a given industry. In establishing these standards, the EPA assesses the performance of the best pollution control technologies or prevention practices available for the industry, as well as the economic achievability of those technologies and practices.
