As spring rains approach, the need for more stringent stormwater controls comes into sharper focus. Rain is a life-giver, of course, but in our ever more paved environment, it’s also a conveyance for water pollution. Stormwater runoff in urban areas travels across rooftops, roads, sidewalks and eventually into a municipal storm sewer system, all the while accumulating a cocktail of various pollutants that includes oil residue from roads, pesticides and excess fertilizer from lawns and farms, and more. These pollutants flow into in local streams and have a direct — and sometimes severe — impact on the water quality and local aquatic ecosystems.

Regulation of Municipal Separate Storm Sewer Systems (MS4s) is critical to improving water quality as envisioned by the Clean Water Act (CWA). Unfortunately, management of stormwater is not a “one size fits all” problem. Controlling runoff of sewage and trash, which are major pollutants in Baltimore City, requires fundamentally different controls than addressing runoff of nitrogen and phosphorous, the major sources of stormwater pollution on the Eastern Shore of Maryland. In addition, the extent of development, and the resulting differences in how much area is covered with pavement and other impervious surfaces, affect how localities can effectively mitigate …