EarthWorks Geospatial Catalog

Areas of Critical Environmental Concern (Polygons)

The Areas of Critical Environmental Concern (ACEC) datalayers provide digital polygon and line boundaries for areas that have been designated ACECs by the Secretary of Energy and Environmental Affairs (EEA). ACECs are places in Massachusetts that receive special recognition because of the quality, uniqueness and significance of their natural and cultural resources. These areas are identified and nominated at the community level and are reviewed and designated by the state’s EEA Secretary. ACEC designation creates a framework for local and regional stewardship of these critical resource areas and ecosystems. ACEC designation also requires stricter environmental review of certain kinds of proposed development under state jurisdiction within the ACEC boundaries. The ACEC Program is administered by the Department of Conservation and Recreation (DCR) on behalf of the Secretary of Environmental Affairs. The Massachusetts Office of Coastal Zone Management (CZM) Office administered the original Coastal ACEC Program from 1978 to 1993, and continues to play a key role in managing coastal ACECs. Procedures for ACEC designation and the general policies governing the effects of designation are contained in the ACEC regulations (301 CMR 12.00). For more information about the ACEC datalayer or about the effects of ACEC designation, contact the ACEC Program at (617) 626-1394 or see The ACEC datalayers have been compiled by CZM and DCR and include both coastal and inland areas. For more information on ACEC maps and boundaries, see To view the map index sheet of detailed ACEC maps (USGS topographic maps with ACEC boundaries), visit and to view the individual map tiles see the links on the individual ACEC Designation web pages, New ACEC polygons (and corresponding boundary lines) are added periodically, as new ACEC nominations are reviewed and designated on an ongoing basis. New nominations and designations are noticed in the EEA Environmental Monitor. As of April, 2009 there are coded boundary arcs available for 10 of the 30 ACECs, part of an ongoing datalayer update program begun in 2003. These coded boundaries indicate what features are used for various ACEC boundary line segments, such as roads, town lines, or wetlands resource areas. The other 20 ACECs do not yet have individually coded arcs, but are shown in the line layer with arcs coded ‘NOT DEFINED.’ Boundaries are also periodically clarified for better agreement with new GIS datalayers – designated boundaries do not change, but the accuracy with which they are described and mapped is improved. Discrepancies are more obvious with older boundaries, and at this time the 2008 Three Mile River Watershed ACEC boundary does not align with the adjacent 1990 Hockomock Swamp and 1991 Canoe River Aquifer ACECs which need to be clarified. THIS DATALAYER IS INTENDED TO BE USED FOR PLANNING PURPOSES ONLY AND WITH THE WRITTEN BOUNDARY DESCRIPTIONS CONTAINED IN EACH ACEC DESIGNATION DOCUMENT. The mapped boundary is not to be used by itself for definitive ACEC boundary delineation or regulatory interpretation. For review of site-specific projects within the ACEC boundary, determinations may need to be made in the field or in consultation with ACEC Program staff. These datalayers are stored in ArcSDE and distributed as ACECS_POLY and ACECS_ARC.
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