EPA Region 1 continues to roll out new programs on the stormwater front, and this week’s development is particularly important for private property owners in the Charles River watershed. The agency released proposed amendments to the Residual Designation for the Charles River (“RDA”) and a Draft General Permit for Residually Designated Discharges. While the proposed permit only affects the Massachusetts communities of Milford, Bellingham, and Franklin, EPA has stated that it may expand the General Permit to include other Charles River communities in the future, so property owners along the entire length of the Charles River should be paying attention.

The full set of materials can be found on the EPA’s website, but here are a few highlights:

2-acre threshold: “Designated Discharges” covered by the permit consist of two or more acres of privately-owned impervious surfaces. (Many publicly-owned properties located in the Charles River basin will be subject to the Massachusetts North Coastal Small MS4 General Permit, released in draft by EPA Region 1 earlier this year.)

Aggregation: As those of you following stormwater issues in Massachusetts are aware, the first draft of the RDA was linked to the proposed state stormwater regulations, which included an “aggregation rule” with a number of onerous consequences. The amended RDA and the draft General permit are no longer connected to the stalled state regulations, but they still include the concept of requiring a single permit for contiguous but separately owned properties that share stormwater controls. Fortunately, unlike the state proposal, each co-permittee will only be responsible for ensuring compliance for “all terms and conditions of this permit applicable to the activities that it controls or has the right to control.”

Permit requirements: The draft permit includes a series of stormwater control requirements including a 65% phosphorus load reduction target (derived from the Lower Charles River TMDL) that permittees can implement on-site through structural or non-structural controls or through a “Certified Municipal Phosphorus Program.”

Comments are due June 30. We expect EPA to take a lot less time to finalize these documents than MassDEP has taken to finalize its own stormwater program.