OVERVIEW

This datalayer contains the watershed extents for all surface water supplies including active, inactive, emergency, sources outside of Massachusetts, watersheds that extend into other states and watersheds of sources from other states that extend into Massachusetts. Surface water intakes on Class B Rivers are not included in this datalayer, with the exception of Horn Pond in Woburn where the water is drawn in through wells adjacent to the shoreline.  Please refer to the Surface Water Supply Protections Zones datalayer and the Public Water Supplies datalayer for information regarding regulated protection zones and public water supply intake information.

The layer is named SWP_WATERSHEDS_POLY.

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.

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.

The attributes for each feature are:

SOURCE_ID		Surface water supply source-id from the Public Water Supply datalayer; RI sources are coded as RHODEISLAND
TYPE		PWS Type. See Public Water Supply datalayer for current:  SW – Surface Water (Active or Inactive)  ESW – Emergency Surface Water  RI – Rhode Island Source
SITE_NAME		Site Name of the reservoir or intake, taken from the Public Water Supply datalayer
WSHEDACRES		Area of the entire watershed in acres
RESVRACRES		Area of the reservoir in acres
ZONEAACRES		Area of the Surface Water Supply Protection Zone A in acres
ZONEBACRES		Area of the Surface Water Supply Protection Zone B in acres
ZONECACRES		Area of the Surface Water Supply Protection Zone C in acres
SUPPLIER		Public Water Supplier Name, taken from Public Water Supplies datalayer
TOWN		Town name of the supplier
REG_OBJ_ID		MassDEP Facilities Regulated Object ID

MAINTENANCE

The Massachusetts Department of Environmental Protection (DEP) GIS Program is maintaining this datalayer. Any updates sent to MassGIS will be forwarded to DEP and incorporated into this data layer. Please reference the town, water supplier id, water supply source id (if known), and major basin identifier when providing updates.

May 2007 – Wenham Lake Reservoir (3030001-01S) zones updated.
July 2007 – Watersheds updated for all sources in Beverly, Peabody and Lynn.

Last Updated 1/9/2008
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