The U.S. Environmental Protection Agency has reached proposed settlements with several environmental and developer organizations, as well as two Massachusetts municipalities, over implementation of its small Municipal Separate Storm Sewer System (MS4) permits in Massachusetts and New Hampshire.

MS4, a type of National Pollutant Discharge Elimination System permit issued by EPA regional offices, authorizes certain discharges of stormwater to surface waters.

The most recent iteration of the MS4 permits were issued for Massachusetts in 2016 and for New Hampshire in 2017, replacing a permit issued in 2003. Environmental groups, including the Conservation Law Foundation and the Charles River Watershed Association, sued the EPA in 2017 to expedite implementation of the permit and ensure that it met stringent environmental and public health standards. Around the same time, several home builder and developer organizations, along with the town of Franklin and the city of Lowell, sued the EPA over the anticipated financial impact of the stricter regulations.

According to an EPA press release, the proposed settlements, announced on Dec. 27, are “the outcome of all parties’ efforts to ensure that, when fully implemented, both MS4 permits protect the environment, adhere to the Clean Water Act and EPA regulations, and address municipalities’ implementation concerns.

“Upon execution of these settlement agreements (or subsequently modified and noticed settlement agreements, as necessary), EPA will then propose and offer the opportunity for public comment on the agreed-upon permit modifications to both the Massachusetts and New Hampshire MS4 permits.”

Under the settlements, approximately 55 of the 250-plus MS4 communities would be able to request extensions to comply with the new pollution reduction requirements.

MMA Executive Director Geoff Beckwith said that local officials are committed to reducing pollution, but are also concerned about the financial impact of MS4 compliance. He estimated that many municipalities face outlays of tens of millions of dollars to comply with the MS4 permit requirements, “without meaningful federal funding support, which would require cutting back on important municipal services, asking voters to approve tax overrides, or increasing water and sewer charges for ratepayers.”

Stormwater runoff from roads, parking lots, construction sites and other impervious surfaces is the largest contributor of pollutants to rivers, streams, ponds and lakes. Rain and snowmelt can pick up oil, grease, sediment, and phosphorous, among other pollutants, which then find their way to waterways. This can lead to toxic algae outbreaks that harm wildlife and human and animal health.

The MS4 permit is intended to regulate the discharge of stormwater into waterways so as to reduce potential negative environmental and public health impacts.

The environmental groups participating in the negotiated settlement advocated for the inclusion of nature-based solutions for stormwater management in new and redevelopment projects and stricter protections against polluted stormwater runoff that leads to toxic algae blooms. The Conservation Law Foundation contends that cities and towns have not effectively met their responsibility for reducing water pollution and the settlement “forces them to prioritize protecting our waters.”

The MMA has long advocated for the Massachusetts Department of Environmental Protection to have delegated authority over NPDES permits, including MS4. The MMA also continues to advocate for more federal and state funding for environmental and water infrastructure, which would shift the burden imposed by unfunded mandates on municipalities.

The proposed settlement agreement and links to the amended permits are posted to the Federal Register at

Public comments were accepted through Jan. 27.

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