Watershed-Based Residual Designation Actions in New England
- EPA's Residual Designation Authority
- Petitions to Designate Certain Properties in the Charles River Watershed, Mystic River Watershed and Neponset River Watershed
- Petition to Designate Certain Properties in the Great Bay Estuary Watershed
- More Information
EPA's Residual Designation Authority
The Clean Water Act (CWA) and related regulations define the specific construction, industrial and municipal stormwater sources that must be authorized by an NPDES permit. The CWA also recognizes that other sources may need to be regulated on a case-by-case or category-by-category basis based on additional information or localized conditions. The authority to regulate other sources based on the localized adverse impact of stormwater on water quality through NPDES permits is commonly referred to as the "Residual Designation" authority.
EPA can use its "residual designation" authority under 40 CFR 122.26(a)(9)(i)(C) and (D) to require NPDES permits for other stormwater discharges or category of discharges on a case-by-case basis when it determines that:
- the discharges contribute to a violation of water quality standards,
- are a significant contributor of pollutant to federally protected surface waters, or
- controls are needed for the discharge based on wasteload allocations that are part of "total maximum daily loads" (TMDLs) that address the pollutant(s) of concern.
In addition, designation can be requested by petition.
EPA's Residual Designation Authority webpage contains additional information on EPA's Residual Designation Authority.
Petitions to Designate Certain Properties in the Charles River Watershed, Mystic River Watershed and Neponset River Watershed
On May 9, 2019, the Conservation Law Foundation (CLF) and the Charles River watershed Association (CRWA) submitted to the Regional Administrator of EPA Region 1 a "Petition for a Determination that Certain Commercial, Industrial, Institutional, and Multi-Family Residential Property Dischargers Contribute to Water Quality Standards Violations in the Charles River watershed, Massachusetts, and that NPDES Permitting of Such Properties is Required." On August 24, 2020, CLF followed this submission with two additional petitions requesting the same residual designations for two other watersheds in Massachusetts: the Mystic River watershed and the Neponset River watershed. The three petitions call for "a determination pursuant to 40 C.F.R. § 122.26(f)(2) that discharges of stormwater that are not currently subject to direct permitting by EPA from privately owned commercial, industrial, institutional, and multi-family residential real properties of one acre or greater" in the Charles River, Mystic River, and Neponset River watersheds "contribute to violations of water quality standards" in the Charles River and Boston Harbor, of which the Mystic River watershed is a sub-basin, and (3) the Neponset River, "and require permits under the National Pollutant Discharge Elimination System ('NPDES')." The petitions can be found here:
- Charles River Watershed RDA Petition (pdf)
- Mystic River Watershed RDA Petition (pdf)
- Neponset River Watershed RDA Petition (pdf)
EPA's RDA Designation for the Charles River, Mystic River and Neponset River Watersheds
On September 14, 2022, EPA exercised its residual designation authority in response to the water quality impacts caused by stormwater discharges in all three watersheds as well as responding to the petitions received for the three watersheds. EPA's action will supplement a watershed-wide approach that already includes significant decades-long investments by municipalities to comply with their Municipal Separate Storm Sewer (MS4) permits; wastewater treatment plant upgrades in the region, including the creation of the new Deer Island treatment plant; the near-elimination of combined sewer overflows (CSOs); and intensive efforts to find and eliminate illicit discharges of sewage into stormwater systems. Cities and towns in these three watersheds have made significant efforts to reduce phosphorus in municipal stormwater and are subject to permits that will require them to do much more in coming years. A significant portion of the phosphorus load also comes directly from privately-owned or unregulated sources, and residual designation could provide a mechanism to reduce the load from these sources, complementing the work municipalities are doing on municipal property under their MS4 permits.
EPA is designating for NPDES permitting certain commercial, industrial, and institutional properties with one or more acres of impervious surface in the Charles River watershed, Mystic River watershed and Neponset River watershed. No action is required by these properties at this time. EPA will draft and finalize a NPDES general permit covering these dischargers, at which time all designated properties will be required to obtain permit coverage under that permit (or an individual NPDES permit if they prefer), and take steps to reduce pollutants in stormwater. More information is below:
- EPA Designation and Attachments (pdf)
- EPA Press Release
- Letter from EPA to the Conservation Law Foundation (pdf)
Updates to RDA General Permit(s) Development and Stakeholder Outreach Activities for the Charles River, Mystic River and Neponset River Watersheds
- General Updates:
- Stakeholder Presentations:
- April 1st, 2024: Presentation to the Association of Independent Colleges and Universities Massachusetts and Massachusetts Health and Hospital Association RDA Presentation (pdf)
- March 22nd, 2024: Presentation to NAIOP/495 Partnership RDA Presentation (pdf)
- March 14th, 2024: Presentation to the Mystic River Watershed Association RDA Presentation (pdf)
- March 7th, 2024: Presentation to the Charles River Watershed Association (pdf)
- February 28th, 2024: Presentation to the Massachusetts River Alliance (pdf)
- January 17th, 2024: Presentation to the Neponset River Watershed Association (pdf)
- Technical Documents
- Stakeholder Outreach Prior to 2024:
Petition to Designate Certain Properties in the Great Bay Estuary Watershed
More information
For additional information contact: R1.RDA@epa.gov