MassGIS Data: MassDEP Ground Water Discharge Permits

December 2021

The Ground Water Discharge Permits datalayer (formerly known as Groundwater Discharge Points) is a statewide point dataset containing approximate locations of permitted discharges to groundwater. Current as of December 23, 2021.

Table of Contents



The Massachusetts Department of Environmental Protection (MassDEP) Bureau of Water Resources (BWR), Wastewater Management Program is responsible for regulating the discharge of pollutants to the groundwaters of The Commonwealth (314 CMR 5.00). See the MassDEP Groundwater Discharge Permitting website for details.

The permitted discharges in this datalayer include:

  • Sanitary sewage in excess of 10,000 gallons per day (gpd)
  • Discharges from coin operated laundromats
  • Discharges from car washes
  • Discharges from industrial facilities
  • Reclaimed water (used in cooling towers and other closed-loop systems, no actual discharge)

In ArcSDE the layer is named GWP_PT.


Source Materials

Locations contained in this datalayer are based on Wastewater Management Program (WMP) staff interpretation of site plan maps that accompany the Groundwater Discharge Permit Applications. The WMP provides the MassDEP GIS Program with verified locations, as well as a database of Ground Water Discharge Permits for the purpose of maintaining this datalayer.

Automation Methodology

Collection of point locations began in 1989 and is ongoing. Originally discharge point locations were marked on USGS quadrangle sheets for use by MassDEP technical staff. These locations were digitized to create the original Groundwater Discharge Permits datalayer.

Following the initial datalayer creation, permit locations were collected using GPS (Global Positioning Systems) with a Trimble Navigation GeoExplorer GPS receiver and differential correction.

Currently, the WMP uses on-screen digitizing with digital base imagery and ancillary data such as parcels, MassDEP-regulated facility locations, etc., along with the permit application site plans. To facilitate data entry with documentation, the GIS Program created the Point Development Tool (PDT) which captures metadata as the location is entered.


The point attribute table for the MassDEP Ground Water Discharge Permits datalayer contains the following fields:

PER BWR Permit Number, Unique site ID
PERR BWR Permit Number plus Renewal Number, Unique site ID
NAME GWP Name, according to the Ground Water Permits database
ADDRESS GWP Address, according to the Ground Water Permits database
TOWN Standard (1-351) MassGIS town name in which the GWP is located
REGION Standard (1-4) DEP Region ID in which the GWP is located:
 1 = Western
 2 = Central
 3 = Northeast
 4 = Southeast
BASIN Basin (watershed) in which the GWP is located
TYPE Status / type of discharge according to WMP:
 C = Car Wash
 = Industrial
 L = Laundromat
 RU = Reclaimed Water
 S = Sanitary Discharge
 O = Other
Note: a small number of features are coded with the combined TYPEs of L/C or S/C.
FLOW Metered flow of discharge; in gallons per day (GPD) according to the Ground Water Permits database

Related Datalayer

MassDEP Location Documentation Table (GWP_PT_LDT) - See MassDEP Standards for Point GIS Data.


The MassDEP GIS Program in cooperation with the WMP maintains this datalayer. Updates to this datalayer will be done on a semiannual basis (April & October). As a standard component of the update, the GIS Program will remove from the datalayer sites that are no longer groundwater discharge points according to the latest WMP data. Datalayer updates may also include refinements to existing site locations.

If you have questions regarding this datalayer, please contact the MassDEP GIS Program at (617) 574-6856. General and technical questions regarding discharges to groundwater permitting should be directed to the MassDEP Wastewater Management Program (617) 556-1150.

Last updated: December 29, 2021