Open space and environment

Flooding and stormwater

Ida set a 59-year record on Beden Brook in 2021 and produced 40 flood-insurance claims in the township, most outside FEMA's high-risk zone. The state is buying and demolishing four damaged homes, the township has rebuilt basins and a sewage-plant floodwall, and eight towns led by Montgomery are writing a Lower Millstone watershed plan.

Checked against the primary record on . Every figure on this page is sourced at the foot of the article.

Regional plan draft due this fall; state plan due Dec 1, 2027 Last moved

What happens next

Watch for the Lower Millstone draft plan and its public comment period (promised for fall 2026), the last two Blue Acres demolitions (scheduled for late October–November 2026), the Watershed Assessment Report (due January 1, 2027) and the final Watershed Improvement Plan (due December 1, 2027). Public comment is open at Township Committee meetings on November 12, December 3 and December 17.

Montgomery’s flooding comes from its streams and the Millstone River, not the coast. The remnants of Hurricane Ida on September 1–2, 2021 produced the highest peak in 59 years of records on Beden Brook near Rocky Hill. They also put about six feet of water into the Stage II sewage plant and led to 40 federal flood-insurance claims in the township, paying about $2.3 million. Most of those claims were on properties outside FEMA’s 100-year flood zone.

Since then the state’s Blue Acres program has agreed to buy Ida-damaged homes, which the township will manage as open space (Res. #25-5-184, May 2025). Township records show four homes in demolition work orders: two were demolished in spring 2026 and two were scheduled for late 2026. The township has built a $19.4 million floodwall at the Stage II plant (its completion date was extended to March 2026; no completion certificate has been found), is rebuilding two detention basins as bioretention basins with a state grant, and has demolished its old municipal building at 2261 Route 206 for floodplain restoration along Cruser Brook. The public works yard on Harlingen Road sits in a floodplain. Moving it has been discussed, but there is no project or cost.

Montgomery is the lead agency for an eight-town Lower Millstone watershed plan ($254,300; Montgomery’s share up to $89,683; a state grant may cover it). A draft was promised for fall 2026 and has not been posted. That plan feeds the state-required Watershed Improvement Plan, due December 1, 2027.

Residents can check their flood zone on FEMA’s map, comment on the regional draft when it is released, and raise local drainage problems at Township Committee meetings. The state-land site sketched for a future public works yard is tracked under state lands.

Flooding and stormwater, explained

Timeline

Each dated event on this issue, oldest first, linked to the full sourced entry.

  1. Milestone Ida sets a 59-year flood record on Beden BrookThe remnants of Hurricane Ida drove Beden Brook near Rocky Hill to 20,600 cubic feet per second, the highest of 59 annual peaks on record. The storm flooded the Stage II sewage plant and led to 40 flood-insurance claims in Montgomery, paying $2,304,545.
  2. Milestone Township agrees to manage land from state Blue Acres buyouts of Ida-damaged homesThe Township Committee voted 4-0, one member absent, to sign a memorandum of understanding with NJDEP's Blue Acres program (Res. #25-5-184). The state buys homes Ida damaged, and the township manages the cleared land as open space.
  3. Active Montgomery hires a consultant for a regional Lower Millstone watershed planThe Township Committee voted 4-0, one member absent, to hire One Water Consulting for $254,300 to write a flood and water-quality plan shared with neighboring towns (Res. #25-5-179). In December 2025 eight towns signed on, with Montgomery as lead agency and paying up to $89,683.

Explainers

  • Flooding and Stormwater in Montgomery: What Ida Did, What Is Being Built, and What Comes Next

    Montgomery's flooding comes from its streams and the Millstone River. Ida in 2021 set a 59-year record on Beden Brook, put about six feet of water into a township sewage plant and produced 40 federal flood-insurance claims, most of them outside FEMA's high-risk zone. Since then the state has bought Ida-damaged homes, the township has built a floodwall and rebuilt two basins, and eight towns are writing a regional watershed plan. The draft is due this fall, and a state-required plan is due December 1, 2027.

Sources for this overview

  1. USGS annual peak streamflow, Beden Brook near Rocky Hill (01401600)
  2. OpenFEMA, FIMA NFIP Redacted Claims (community 340439)
  3. Township Committee minutes, May 15, 2025 (Res. #25-5-184 Blue Acres MOU; Res. #25-5-179)
  4. Township Committee minutes, December 18, 2025 (Res. #25-12-418; Blue Acres work orders)
  5. Montgomery Township: Lower Millstone Watershed Plan
  6. Planning Board minutes, December 8, 2025 (Stormwater Management Plan)
  7. New Jersey Future, MS4 Permit Primer, January 2026 (deadlines)
  8. Notice of contract award amendment, former municipal building, October 2026
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