The U.S. Geological Survey’s StreamStats program is a publicly-accessible web application (https://streamstats.usgs.gov) that can be used to delineate drainage areas, compute basin characteristics, and estimate flow statistics for user-selected locations on streams. StreamStats services are typically implemented at the statewide or watershed scale (referred to as state or basin applications), and although the three core functionalities remain consistent, many states have implemented custom tools to address specific water-resources planning and management needs. In Massachusetts, a watershed-scale application for the Mystic River Basin was developed to support stakeholder efforts to address stormwater challenges in this highly urbanized basin. The Mystic River Basin stormwater functionality was developed by incorporating 1-meter resolution lidar-derived elevation data and municipal storm drain data to accurately represent urban topography and stormwater flow (that is, subsurface piped flow). In the Mystic River Basin application, users can view the network of stormwater pipes and inlets, delineate drainage areas derived from lidar topography and stormwater infrastructure, and compute land-use/land-cover (LULC) basin characteristics. This data release contains the LULC data available in the Mystic River Basin StreamStats application as a Georeferenced Tagged Image File Format (GeoTIFF) raster dataset. This dataset was developed by processing Massachusetts 2016 LULC data (MassGIS, 2019) and Soil Survey Geographic data (SSURGO; NRCS, 2020) according to Massachusetts Department of Environmental Protection guidelines to produce categories consistent with the 2016 Massachusetts Small Municipal Separate Storm Sewer System (MS4) General Permit Pollutant Loading Export Rates for aggregated land uses (Schifman, 2022). References: MassGIS, 2019, 2016 Land Cover/Land Use: MassGIS Bureau of Geographic Information, accessed April 11, 2022, at https://www.mass.gov/info-details/massgis-data-2016-land-coverland-use. Natural Resources Conservation Service [NRCS], 2020, Soils Polygons for Massachusetts with "Top 20" Fields: MassGIS Bureau of Geographic Information, accessed December 1, 2021, at https://www.mass.gov/info-details/massgis-data-soils-ssurgo-certified-nrcs. Schifman, L.A, 2022, 2016 Massachusetts Small MS4 Permit Pollutant Loading Export Rates applied to the 2016 Massachusetts Land Use/Land Cover GIS Dataset: Massachusetts Department of Environmental Protection, 7 p., accessed May 23, 2022, at https://www.mass.gov/doc/2016-massachusetts-small-ms4-permit-pollutant-loading-export-rates.