The MassDEP Hydrography layer is an enhanced version of the 1:25000 Hydrography datalayer. It represents hydrographic (water-related) features, including surface water (lakes, ponds, and reservoirs), wetlands, bogs, flats, rivers, streams, and others (see below). The layer is a hybrid of data based on USGS Digital Line Graphs (DLGs), scanned mylar separates obtained from the USGS, digitized hydrographic features from paper USGS 1:25,000 Topographic Quadrangle maps and data extracted from the MassDEP Wetlands datalayer. Areas within many surface water supply watersheds have been enhanced by using higher resolution streams and lakes from the MassDEP Wetlands datalayer, many areas have also been field verified. This layer is intended as an interim product that will be incorporated into the USGS's National Hydrography Dataset (NHD) when funding and resources become available. If you are interested in providing data, funding, field work, or becoming part of an NHD working group, please contact Robert Hames of the MassDEP GIS Program by email at Robert.Hames@state.ma.us
