This layer depicts the seven Sole Source Aquifer (SSA) in Massachusetts. A SSA is an aquifer designated by US EPA as the 'sole or principal source' of drinking water for a given aquifer service area.
(ESRI Shapefile with ArcGIS .lyr and ArcView 3x .avl)
MethodologyThe aquifers were defined by a EPA hydrogeologist. Aquifer boundaries were then drafted by EPA onto 1:25,000 USGS quadrangles. For the coastal sole source aquifers the shoreline as it appeared on the quadrangle was used as a boundary. Delineated boundaries were then digitized into ARC/INFO. However, to ensure that aquifer boundaries coincide with MassGIS coast data, the ARC RESELECT command was used to select the aquifer boundaries for Martha’s Vineyard, Nantucket and Cape Cod SSAs. The coastal SSA boundaries are fluid and change with the change of shore line. Checkplots of the aquifers were submitted to US EPA Region 1 for verification.
AttributesThis datalayer's attribute table has the following attributes associated with each polygon:
|SSA_NUM||a unique id for each SSA|
|SSA_NAME||the name of the SSA|
|SOURCE_CODE||the source of SSA linework|
MaintenanceThe DEP Division of Water Supply and MassGIS are maintaining this datalayer.
Last Updated 6/7/2004
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English (United States)