This database shows the location of publicly owned treatment works, and other significant point source discharges to surface waters at or near the contiguous U.S. coastline. Three types of features are provided in this database: facility location, outfall pipes, and the outfall discharge point. Outfall pipes and discharge points may not be present for some facilities due to a lack of source data. A facility can be linked to its outfall pipe, discharge point, and other National Pollution Discharge Elimination System records using the provided key field.Direct data download | MetadataThis item is curated by the MarineCadastre.gov team. Find more information at marinecadastre.gov.

The 2021 Combined Sewer Overflow (CSO) spatial data layer shows the point locations of National Pollutant Discharge Elimination System (NPDES) permitted combined sewer overflow discharges. These outfalls occur in older cities in Massachusetts that still have areas of combined sewer and stormwater systems which overflow during heavy storm events. MassDEP has responsibility for ensuring that these systems, along with other sanitary sewer systems, are in compliance with the Clean Waters Act https://www.epa.gov/laws-regulations/summary-clean-water-act and the regulations adopted under 314 CMR 1.00 through 9.00 – please see https://www.mass.gov/regulations/314-CMR-9-401-water-quality-certification for more detail. Please refer to the Sanitary Sewer Systems and Combined Sewer Overflows guide for additional information.A list of active CSO locations was created and checked against lists contained in the NPDES permit for each CSO system along with lists contained in reports available from the systems online or on town websites. In some cases, when needed, CSO systems were contacted to verify active status of outfalls.Outfall locations are estimates based on the best available maps or coordinates and may contain errors and should only be used as a guide. For additional locational information please contact the CSO systems involved.Source Materials and Data AutomationMassDEP staff used information including maps and general descriptions of CSO locations found online and in NPDES permits to assist in mapping. This information was supplemented by maps and coordinates received from municipal staff responsible for CSO management in each of the systems involved, staff knowledge of outfall locations, maps found in system reports, and maps found on town web sites. MassDEP staff viewed the material and then mapped or verified the location of the CSO using the 2019 orthophoto as a basemap. Some systems were able to provide GIS data directly to MassDEP staff – in these cases, CSO locations were placed directly onto the provided points s or the systems provided point locations were used to verify MassDEP locations. When available, coordinates were entered directly and then checked against the orthophoto and other available maps for general accuracy. Last updated July, 2021.

FIELD

TYPE/WDTH

DEFINITION

NPDES_ID

C/50

Permit Number for the National Pollutant Discharge Elimination System (NPDES)

SYSTEMNAME

C/50

CSO System Name

OUTFALL_ID

C/15

Outfall number according to the Town or System

DEP_OUTFL_ID

C/15

Unique ID for the CSO which combines the Town or System abbreviation with the CSO Outfall No

RECVING_WATER

C/100

The body of water the CSO drains into

ADDRESS

C/120

General locational description of the CSO

TOWN

C/40

Standard (1-351) municipality name where the CSO is actually located

DEP_REGION

C/4

MassDEP Regional Office Code

L_TYPE

C/10

Type of location, i.e., estimated location, center of site, etc.

POINT_X

D

X Coordinate Decimal Degrees

POINT_Y

D

Y Coordinate Decimal Degrees

MAJOR_BASIN

C/100

Major Basin the outfall is located within

PERMIT_URL

C/200

URL to permit online

Data Universe

A list of active CSO locations was created and checked against lists contained in the NPDES permit for each CSO system along with lists contained in reports available from the systems online or on town websites. In some cases, when needed, CSO systems were contacted to verify active status of outfalls.CONTACTS AND TERMS OF USE

The CSOs contained in the CSO spatial data layer are based on a list provided by the MassDEP Bureau of Water Resources Wastewater program – for general questions please contact Lealdon Langley at (617) 574-6882. Locations are estimates and should only be used as a guide. For additional locational information please contact the CSO systems involved. For GIS related questions please contact the MassDEP GIS Program at (617) 292-5500.

CSO attributes and location information are from a variety of datasets for each state: Connecticut: Beginning with GIS data compiled by the Connecticut Department of Energy and Environmental Protection (“CT DEEP”) and displayed on their CSO Right-to-Know site (https://portal.ct.gov/DEEP/Municipal-Wastewater/Combined-Sewer-Overflows-Right-to-Know), EPA filtered the data for the purposes of this map and made corrections based upon updated information available in EPA’s files. EPA’s map only displays municipalities with CSO outfalls, whereas CT DEEP’s map includes municipalities with CSO-related bypasses at their Wastewater Treatment Facilities (but no Combined Sewer Collection System CSO outfalls). EPA’s map only displays CSO outfalls – the point at which CSOs are discharged to the receiving water - whereas CT DEEP’s map includes CSO regulators (the structure through which wastewater and stormwater exits the conveyance pipe towards the Wastewater Treatment Facility). Maine: Service containing both facility and outfall locations permitted under the Maine Pollution Elimination System (MEPDES) and administered by the Maine Department of Environmental Protection (MEDEP). The data has been collected using multiple methods over 2 decades under the direction of the Maine DEP GIS Unit. All location data was quality checked by MEDEP MEPDES Inspectors and GIS Unit staff in 2018. Massachusetts: Attribute and location information from a combination of MassDEP CSOs(https://mass-eoeea.maps.arcgis.com/apps/webappviewer/index.html?id=08c0019270254f0095a0806b155abcde) (metadata - https://mass-eoeea.maps.arcgis.com/home/item.html?id=0262b339c2c74213bdaaa15adccc0e96) and NPDES permits(https://www.epa.gov/npdes-permits/massachusetts-final-individual-npdes-permits). New Hampshire: Active CSO outfalls collected from NH NPDES permits(https://www.epa.gov/npdes-permits/new-hampshire-final-individual-npdes-permits). EPA made corrections based upon updated information available in EPA’s files. Rhode Island: RI CSO Outfall Point Features. The outfalls managed by the Narragansett Bay Commission are downloadable from a GIS file through RIGIS (Rhode Island Geographic Information System https://www.rigis.org/datasets/nbc-sewer-overflows/explore?location=41.841121%2C-71.414224%2C13.57&showTable=true). Data was intended for use in utility facility engineering structure inventory. Last updated: 2019. Downloaded: 11/19/2021. Metadata (https://www.arcgis.com/sharing/rest/content/items/2108bab269df47f988e59c18a556f37d/info/metadata/metadata.xml?format=default&output=html) Vermont: Attribute and location information from Vermont Open Geodata Poral (https://geodata.vermont.gov/datasets/VTANR::stormwater-infrastructure-point-features/explore?location=43.912839%2C-72.414150%2C9.29). Point, line, and polygon data was collected and compiled through field observations, municipal member knowledge, ortho-photo interpretation, digitization of georeferenced town plans and record drawings, and state stormwater permit plans. Accuracy of all data is for planning purposes and field verification is at the user’s discretion. VT Layer: Stormwater Infrastructure (Point Features) Metadata (https://www.arcgis.com/sharing/rest/content/items/5c9875ee609c4586bd569dbacb2d92f1/info/metadata/metadata.xml?format=default&output=html).