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MassGIS Data: Dams

February 2012

The Massachusetts Dams data layer contains points derived from a dam safety database maintained by the Massachusetts Office of Dam Safety (ODS). The ODS database includes detailed information about each dam for operational purposes.

*Note (12/14/2018): This layer has not been updated since 2012. The current status of several points have not been verified and not all locations have been confirmed. DCR is working with the Office of Dam Safety on an update. It will be posted here once it is complete.

*Note (3/31/2021): The name of Brazell Dam in Templeton was changed to Betty Pond Dam per the Office of Dam Safety. A full statewide update is still forthcoming and will be posted here once it is complete.

Table of Contents



Most of the location information was derived from historic data and has been ground-truthed against inspection and ownership reports that are maintained by the ODS. The locations of some dams have not been confirmed. These are pending verification and can be identified through the field 'LocStatus.' Dams regulated by the ODS in accordance with regulation CMR 302 10.00 are listed as 'Office of Dam Safety' in the field 'RegAuth'. Please report any data errors or inconsistencies to the Office of Dam Safety (dam.safety@mass.gov) or DCR-GIS (chandreyee.lahiri@mass.gov)

The datalayer contained an identical number of records as the ODS database at the time it was created. New records subsequently may have been added to the ODS database that are not reflected in this GIS datalayer. There are many additional fields and information maintained by the ODS in its database that are not included in the GIS data. These data have been excluded for privacy, security, accuracy and administrative reasons.

MassGIS stores the GIS datalayer as DAMS_PT.


Original Source Manuscripts and Production

The Massachusetts Office of Dam Safety has historically maintained records of dams through maps, deeds, site visit documentation and correspondence. A unique identifier ('NATID') for each dam links all documents. The original GIS dataset was created from historical documents of varying accuracy in 2001. An organized digital data logging system in recent years has enabled better ground-truthing and location verifications through annual site inspections.

Current Source Manuscripts and Production Methodology

An interactive database is currently used by ODS staff to continually update information about dams.


The DAMS_PT attribute table has the following items:

Field Name Width Type Description /Codes
REGAUTH 254 String The authority responsible for regulating the dam(see below for codes)
FERC Jurisdiction FERC (Federal Energy Regulation Commission) Jurisdiction applies to facilities that generate hydro-electric power and are subject to FERC regulation. May be privately or publicly owned.
Army Corps of Engineers Jurisdiction Dams regulated by the Army Corps of Engineers (ACOE)
Fish & Wildlife Service Jurisdiction Dams regulated by the Fish & Wildlife Service (FWS)
Office of Dam Safety Dams which may be privately or publicly owned but are regulated by and under the jurisdiction of the Massachusetts Office of Dam Safety (ODS) in accordance with regulation CMR 302 10.00.
Non-Jurisdictional – Other NOT regulated by the ODS or under their jurisdiction. Typically under 6 ft in height and/or under 15 acre-feet in storage and do not have an assigned 'Hazard Code'. Dams owned and regulated by the Federal Government are also typically Non-jurisdictional but DO have assigned Hazard Codes.
NATID 254 String Unique ID for the dam in the Office of Dam Safety database
DAMNAME 254 String Currently recognized and official name of the dam
TOWN 254 String Town in which the dam is located
DAMLAT 19 Double Dam location – Latitude in decimal degrees
DAMLONG 19 Double Dam location – Longitude in decimal degrees
HAZCODE 254 String Codes that indicate severity of hazards presented to communities in case of dam failure
High Located where failure will likely cause loss of life and serious damage to home(s), industrial, commercial facilities, important public utilities, main highway(s) or Railroad(s)
Significant Located where failure may cause loss of life and damage home(s), industrial or commercial facilities, secondary highway(s) or railroad(s) or cause interruption of use or service of relatively important facilities.
Low Located where failure may cause minimal property damage to others. Loss of life is not expected.
N/A No hazard code: Non-jurisdictional dams do not have hazard codes except when owned and regulated by the Federal Government.
OWNTYPE1 254 String Basic information on owner type. See OwnType2 for further elaboration.
Public Owned by a public entity
Private Owned by a private entity
OWNTYPE2 254 String More details on owner type. See OwnType3 for further elaboration.
Private Owned by a private entity
Private Association or other non-profit Owned by a private association or a non-profit
State Owned by a state agency. More details in 'OwnType3' field.
Municipality Owned by a municipality. More details in 'OwnType3' field.
Federal Agency Owned by a Federal Agency. More details in 'OwnType3' field.
Political Subdivision Owned by a political subdivision that is neither state nor municipal such as a water district that might have jurisdiction within more than one municipality.
OWNTYPE3 254 String Details on owner type where available
Private Dams are privately owned so names, addresses etc are not publicly shared.
Private Association or other non-profit Dams are privately owned so names, addresses etc are not publicly shared
'City of...' or 'Town of…' For Municipally owned dams, the specific municipal authority
'Water District…' or 'Regional School..' For dams owned by Political subdivisions, the authority name
ACOE or FWS For Federally regulated dams, name of regulating authority.
DCR, DFG, DHE, DOT, DCAM, DMH or MBTA For State owned dams, authority name. More details in field 'MgmtUnit'.
MGMTUNIT 254 String Department or other management unit responsible for dams
MWRA–Operated Dam is operated by Mass. Water Resource Authority
PL–566/Flood Control Dams in the Watershed Protection & Flood Prevention Program (PL-566)
<Other values> Unique names that are self-explanatory e.g. 'Conservation Commission' , 'Board of Selectman' etc (in the case of Municipally owned dams)
LOCSTATUS 30 String Indicates whether geographic location of the dam has been verified
Verified Dam locations have been checked against ODS records
NOT Verified Dam location yet to be verified – should not be considered checked
TOWN_ID 3 Number MassGIS town identifier (1-351)


The shapefile will periodically be updated as better information becomes available in the ODS database. Future data enhancements include verifying all dam locations. Please report any data errors or inconsistencies to the Office of Dam Safety (dam.safety@mass.gov) or DCR-GIS (chandreyee.lahiri@mass.gov)