The Official Website of the Office of Geographic and Environmental Information (MassGIS)
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Surface Water Supply Watersheds - December 2007
OVERVIEW METHODOLOGY Those areas that contribute to public surface water supplies were originally taken from the USGS Drainage Sub Basins datalayer. Starting in 2003, the DEP GIS Program began using the elevation control points and breaklines from the 1:5,000 Digital OrthoPhoto Project to create a digital elevation model of a surface water supply watershed, and using the ArcHydro toolset developed by ESRI and the University of Texas to delineate watersheds digitally.. These basins were then field checked by MassDEP Drinking Water Program staff and edits made when necessary. This work is ongoing and is about 35% complete, with watersheds prioritized by perceived accuracy or if threats to the watershed are identified, with work now progressing in Essex County. Basin extents for watersheds outside of Massachusetts where taken from the NRCS Hydrologic Unit Code (HUC) data or from data provided by other New England states. Where this data was not sufficient basin edges where delineated using the contours from USGS quads in DRG format. The attributes relating to water supply zones in the existing USGS Drainage Sub Basins have been removed.ATTRIBUTES Atrributes include information from the Public Water Supplies datalayer and summary information from the Surface Water Supplies Protection Zones. More detailed information about the source is contained in the Public Water Supplies datalayer. MAINTENANCE
Last Updated 1/9/2008 |
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