Princeton Joins 8-Town Effort to Clean Up Lower Millstone River

PRINCETON, NJ — Princeton has signed on to a regional plan to reduce flooding and cut pollution flowing into the Lower Millstone River, joining seven neighboring municipalities in a collaborative effort required under new state environmental regulations.

The Princeton Council approved a resolution during Monday’s meeting. The town will work alongside Montgomery Township, Franklin Township, South Brunswick, Manville, Hopewell, Hopewell Borough and Rocky Hill Borough on a shared Watershed Improvement Plan — a document the state requires all municipalities to submit by Jan. 1, 2027.

Princeton had already signaled its intention to participate.

"The latest DEP requirements require all municipalities to generate regional watershed improvement plans, but watersheds do not respect municipal boundaries," council member David Cohen said at the meeting. "It's something that is almost nonsensical unless you do it in collaboration with neighboring municipalities."

Council member Leighton Newlin added: "The reason for this is to reduce pollution coming into our waterways from the Millstone River."

New stormwater rules that took effect Jan. 1, 2023, require municipalities to study and address pollution and flooding in local waterways. Because watershed boundaries do not align with municipal or county lines, state officials encourage towns to work together rather than conduct independent studies.

Princeton staff have been attending planning meetings organized by the Watershed Institute since 2024, according to a memo from Deputy Administrator Deanna Stockton.

How it's structured — and how it differs from the Stony Brook plan

Montgomery Township is serving as the lead agency and has hired One Water Consulting LLC to develop the plan. The arrangement differs from Princeton's existing Stony Brook Watershed collaboration, approved in March 2025, in which each municipality contracted individually with One Water Consulting rather than working through a single lead agency and shared agreement.

The total contract cost is $254,300, divided among the eight towns based on their proportional share of the watershed:

• Montgomery Township: 35.27% — $89,683

• Franklin Township: 30.56% — $77,725

• South Brunswick Township: 19.12% — $48,628

• Manville Borough: 5.49% — $13,951

• Princeton: 3.29% — $8,370

• Hopewell Township: 3.13% — $7,972

• Hopewell Borough: 2.04% — $5,182

• Rocky Hill Borough: 1.10% — $2,790

Princeton's share is among the smallest, reflecting that only a small corner of town falls within the Lower Millstone River watershed.

Montgomery has been notified by the DEP that a 2025 water quality restoration grant application was selected for a potential award that could cover the full $254,300 for all participating municipalities, pending execution of a grant agreement.

Cohen noted Princeton's familiarity with this kind of regional collaboration. "We have already engaged in one where a much larger percentage of Princeton is part of the Stony Brook watershed," he said. "This is only a small corner of Princeton that is in this watershed, but I'm glad to see that we're working with the towns that are impacted in this watershed as well."

The agreement runs through Dec. 31, 2027.

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