A toxic algae bloom in the Charles River. (Photo courtesy Charles River Watershed Association)

The U.S. Environmental Protection Agency notified stakeholders in the Charles River watershed on Aug. 13 that the agency is evaluating whether to introduce a new permit regulating stormwater runoff from private parties into the watershed.

A letter from the EPA’s New England Region stated that the agency is considering whether “a new program is needed to control stormwater pollution from certain commercial, industrial and institutional sources in the Charles River watershed at sites that are not currently covered by any existing federal or state stormwater permit.”

With a new permit, the EPA would be operating under its “residual designation authority,” a provision under the Clean Water Act that allows the agency, under certain conditions, to require permits for stormwater discharges that are not otherwise regulated.

The EPA letter notes that stormwater is the largest source of phosphorus pollution in the watershed. Excessive amounts of phosphorus and other nutrients in the freshwater ecosystem can lead to toxic algae blooms, which have been especially prevalent in the Charles River during recent summers, and can be harmful to humans, animals and the ecosystem.

The EPA already regulates municipal discharge of stormwater into rivers and other bodies of water throughout most of the Commonwealth with the Municipal Separate Storm Sewer System (MS4) permit.

In May 2019, the Conservation Law Foundation and the Charles River Watershed Association petitioned the EPA Region 1 to exercise its residual designation authority and regulate stormwater runoff from private parties in the watershed region.

As part of a stakeholder engagement process surrounding the proposed introduction of a new permit, the EPA is conducting outreach to municipal officials and staff from the 35 cities and towns that comprise the Charles River watershed.

On Sept. 16, the MMA co-hosted a webinar with the EPA on the topic for municipal officials from Charles River Watershed communities. The MMA is also helping to coordinate focus groups for municipal officials and staff as part of the engagement process.

Questions about municipal involvement can be directed to MMA Legislative Analyst Ariela Lovett at alovett@mma.org.

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