Small Scale Microwatersheds as a Water Quality Management Tool

Identifying, managing, and eliminating nonpoint source pollution within a watershed or subwatershed is often problematic. In this paper, a new method, the Small Scale Microwatershed (SSMW) Method will be presented. The SSMW method of watershed management applies GIS technologies to help identify, eliminate, and manage nonpoint source pollution. The method is delineated from a parcel base map overlaid with topography, surface water features, wetland features, surface water sampling locations from a long term program, and a digitized map of the municipal separate storm sewer system. Once the final map is produced, the SSMWs can be defined by the parcels that directly impact each sampling point. The SSMWs are not cumulative and are viewed as individual units within the overall watershed or subwatershed.By applying the small scale microwatershed method of watershed management, the Town of Acton, Massachusetts is working to refine an existing twenty year old surface water quality sampling program into the foundation for an Environmental Management System that will encompass the entire town. The SSMW method allows decisions to be made on a smaller scale, effectively identifying nonpoint source pollution issues. Initial results in Acton show that the method has the promise to be a transferable desktop tool for new and existing water quality sampling programs within any size watershed or subwatershed in any type of community.