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, 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 (metadata) and NPDES permits.

New Hampshire: Active CSO outfalls collected from NH 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). Data was intended for use in utility facility engineering structure inventory. Last updated: 2019. Downloaded: 11/19/2021. Metadata

Vermont: Attribute and location information from Vermont Open Geodata Poral. 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