Geospatial Support for the Massachusetts Watershed Planning Program

Pursuant to the federal Clean Water Act (CWA), the Commonwealth of Massachusetts is responsible for monitoring, assessing, and reporting on the quality of lakes, rivers, coastal waters, and other surface waters within the state. In order to account for spatial heterogeneity in physical, chemical, and biological characteristics that can occur across a waterbody’s extent, the Massachusetts Department of Environmental Protection (MassDEP) subdivides waterbodies into one or more Assessment Units (AUs) in order to assess whether state water quality standards are being met over time and report conditions to the U.S. Environmental Protection Agency under Sections 305(b) and 303(d) of the CWA. Historically, MassDEP’s inventory of AUs has been limited in scope due to issues related to data availability, and MassDEP sought assistance in developing standardized methods for expanding AU coverage across the state. To address this need, MassDEP hired ERG to support (1) development of a robust, standardized process for AU delineation across the state, and (2) implementation of this process across select watersheds to develop a novel comprehensive AU spatial dataset used to support future monitoring and assessment efforts.

ERG supported MassDEP’s Watershed Planning Program (WPP) in refining standardized methodologies for delineating surface water AUs and implementing refined methods to delineate AUs within three selected pilot watersheds across the state. ERG began by reviewing and testing WPP’s existing AU delineation Standard Operating Procedures (SOPs) to identify limitations and potential failure points. ERG then worked closely with WPP staff to refine SOPs based on identified methodological vulnerabilities and limitations associated with supporting hydrologic, water quality, infrastructure, and regulatory datasets used to delineate AU spatial boundaries. ERG’s geospatial professionals designed customized, automated workflows to apply revised methods to create a series of AU geospatial datasets representing qualifying waters (including streams, rivers, lakes, ponds, and associated drainage areas) in selected watersheds. Standardized methodologies developed under this effort will eventually be applied to generate a comprehensive AU dataset spanning remaining watersheds within Massachusetts, thereby supporting MassDEP’s surface water quality monitoring, assessment, and reporting efforts under the Clean Water Act.