Impervious surfaces such as paved roads, parking lots, and building roofs can affect the natural streamflow patterns and ecosystems of nearby streams. This data set summarizes the percent of impervious surface for subbasins in Massachusetts using a newly available statewide 1-m binary raster dataset of impervious surface for 2005. Subbasin boundaries include the entire upstream drainage area and are nested such that polygons for headwater basins and tributary streams will overlap with basin polygons delineated further downstream. This is one of three data layers in this data series publication.