The MassGIS 1:25,000 Hydrography datalayer represents hydrographic (water-related) features, including surface water (lakes, ponds, reservoirs), wetlands, bogs, flats, rivers, streams, and others. The layer is a hybrid of data based on USGS Digital Line Graphs (DLGs), scanned mylar separates obtained from the USGS, and digitized hydrographic features from paper USGS 1:25,000 Topographic Quadrangle maps. This layer had previously contained features from the USGS 1:100,000 hydrography; these have been replaced with features from the scanned mylars.IMPORTANT: Please note that because this file is comprised of USGS tiles, the boundaries of the file do not correlate exactly with the border of Massachusetts.