MS4 Outfall Catchment Calculator

The U.S. Environmental Protection Agency recently released a new set of stormwater regulations that will impose stricter requirements on nearly all cities and towns across Massachusetts, beginning in July of 2017. The new regulations will require municipalities to map the land area that contribute stormwater to particular body of water, and to rank these areas according to their risk for introducing pollutants into the water bodies. Municipalities will be able to use the maps as a tool to focus outreach, infrastructure, and enforcement campaigns to property owners or neighborhoods with the ultimate goal of improving water quality. Meeting the new requirements will require technical analysis of hydrology, topography, land use, and stormwater infrastructure.

The Analytical Services group has developed a simple method to conduct this analysis requiring minimal local stormwater infrastructure data in a standardized format. The agency has published a methodology and a set of ArcGIS tools that may be used in municipalities across the Commonwealth.

Get the toolbox here.