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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.
What is happening
Montgomery has no coastline, so its flood risk comes from water running off the land into small streams and the Millstone River. The township’s 2025 stormwater plan names the main waterways: Beden (Bedens) Brook, Pike Run, Rock Brook, Cruser Brook, Cherry Brook and the Millstone. Most flow west to east. The plan says 42% of the township has less than three feet to the seasonal high water table, mostly “adjacent to stream corridors, in the southern portion of the municipality.”
Five years after Ida, flooding is on the township’s agenda in several ways at once. The state has bought homes that Ida damaged. The township has built a floodwall around a sewage plant, rebuilt two stormwater basins and demolished its old municipal building on a flood-prone site. It is also leading an eight-town watershed plan, and it must give the state a stormwater improvement plan by December 1, 2027. None of this has drawn much public comment: when the Planning Board adopted the revised stormwater plan in December 2025, the minutes record “no public in attendance.”
What Ida did
The remnants of Hurricane Ida hit on September 1–2, 2021. The federal stream gauges near Montgomery recorded:
| Gauge | Ida peak | How it ranks |
|---|---|---|
| Beden Brook near Rocky Hill | 20,600 cubic feet per second; 21.06 ft | Highest of 59 annual peaks since 1967 (next: Floyd, 1999, 15,300 cfs) |
| Pike Run at Belle Mead | 2,030 cfs; 15.50 ft | Highest water level on record there |
| Millstone River at Griggstown | 23.22 ft | Second only to Irene in 2011 (24.21 ft) |
FEMA issued an emergency declaration (EM-3573) on September 2 and a major disaster declaration (DR-4614) on September 5, 2021, covering Somerset County. Somerset has had no other flood disaster declaration since then.
Homes. Montgomery’s police director told The Montgomery News in November 2021 that “23 homes received major and significant damage.” FEMA’s flood-insurance records list 40 claims in the township for Ida, which paid $2,304,545. That is more than three-quarters of all money the National Flood Insurance Program has paid in Montgomery since 1999 ($2,925,388 across 75 claims). Irene (2011) is next, with 19 claims and $525,177.
Outside the high-risk zone. Of the 40 Ida claims, 24 are on properties FEMA now maps in Zone X, outside the 100-year floodplain. FEMA removes addresses from this data, and the zone field shows the current map, so the count is a guide rather than an exact measure. FEMA also lists 11 Montgomery properties with repeated insured flood losses. Five are in Zone X, four had their most recent loss on September 1, 2021, and none is marked as mitigated.
The Stage II sewage plant. The township says “the entire Stage II WWTP is within the NJDEP Flood Hazard Area.” It flooded in Floyd (1999), an April 2007 nor’easter, Irene (2011) and Ida. On March 5, 2026 the Administrator read aloud the Township Engineer’s letter to NJDEP. According to the uncorrected captions, it said the township “waited more than 600 days for DEP regulatory permits to construct a flood wall,” and that during that delay Ida “caused over six feet of flooding and significant damage to the treatment plant.” The township later received a $1.1 million FEMA grant for Ida repairs at the plant, according to Headline News.
Since Ida. The Millstone reached major flood stage again on January 10, 2024 (15.94 ft at Griggstown, as reported by The Montgomery News). Drivers were rescued on River Road and on Route 533 near the Griggstown Causeway, and police wrote summonses to drivers who went around “Road Closed” signs. In May 2026 the police and the Office of Emergency Management started a Swift Water Rescue Program, with a vehicle that can work “in up to three feet of moving water.”
Blue Acres buyouts
Blue Acres is the state program that buys flood-damaged homes from owners who want to sell, demolishes them and keeps the land as open space. On May 15, 2025 the Township Committee approved a memorandum of understanding with the program (Res. #25-5-184, 4-0, one member absent). The resolution says Ida caused “extensive damage to several properties” and that NJDEP “has agreed to acquire the Properties.” Once the state buys them, the township manages the land. Permitted uses include “pathways, picnicking and birdwatching” and “reforestation and invasive species control.” The resolution does not list the properties.
What the township’s records show, without addresses:
| Date | Status | Record |
|---|---|---|
| Dec 18, 2025 | Four homes in state demolition work orders: two set for late February 2026, two for “late October-November” 2026 | Administrator’s report, TC minutes |
| Apr 7, 2026 | One of the first two demolished; the second “will be demolished soon” | Environmental Commission minutes |
| May 5, 2026 | Both of the first two demolished | Environmental Commission minutes |
| Oct 23, 2026 | No record yet that the last two have been demolished | — |
The township’s 2025 stormwater plan lists the four lots for possible tree planting and streambank restoration. The purchase prices, and whether federal or state money paid for each home, are not in any public record this site has found. State-owned Blue Acres land does not pay property tax.
The Lower Millstone regional plan
Montgomery is leading eight towns in a joint watershed plan for the lower Millstone River. The towns are Montgomery, Franklin, South Brunswick, Manville, Princeton, Hopewell Township, Hopewell Borough and Rocky Hill. The Watershed Institute organized the work group in October 2024.
- Contract. On May 15, 2025 the Committee voted 4-0, one member absent, to hire One Water Consulting for $254,300 (Res. #25-5-179). The plan is to “identify potential locations, projects and costs within the watershed to reduce water pollution and reduce flooding.”
- Shares. On December 18, 2025 the Committee confirmed the eight participants and made Montgomery the lead agency (Res. #25-12-418, 4-0, one member absent). Montgomery’s share is up to $89,683, or 35.27%. The same resolution says a state Water Quality Restoration Grant, paid as reimbursement, could fund “the entire Watershed Management Plan for all participating municipalities.” The township’s sustainability subcommittee minutes record the award as “$288K.”
- Public input. A public session was held July 14, 2026, and a survey on flooding and drainage problems ran until August 4. Water sampling found phosphorus effects in Beden Brook and Pike Brook.
- Schedule. The consultant’s slides put the plan report in September 2026. On July 16 the Administrator said a draft would be released “for formal public comment sometime in the Fall.” As of October 23, 2026, no draft is posted on the township’s page.
State stormwater rules and deadlines
The MS4 permit. Montgomery holds a state “Tier A” stormwater permit for its storm sewer system. The township’s inventory lists 551 outfalls and 6,130 storm drain inlets. The 2023 version of the permit requires every town to write a Watershed Improvement Plan “to reduce flooding, reduce water pollution” and meet pollution limits for its streams. It has three stages:
| Stage | Deadline | Montgomery status |
|---|---|---|
| Watershed Inventory Report | January 1, 2026 | Submitted December 2025 |
| Watershed Assessment Report | January 1, 2027 | Not yet public |
| Final Watershed Improvement Plan | December 1, 2027 | The Lower Millstone plan is meant to feed it |
January 1, 2027 is the deadline for the assessment report. The final plan is due December 1, 2027.
The township’s own rules. The Planning Board readopted the Municipal Stormwater Management Plan on December 8, 2025, 6-0, after NJDEP “identified the need to update and readopt the plan” during an audit. The plan addresses “flood-prone areas, undersized culverts, and localized erosion concerns.” Since March 2, 2021, Montgomery has treated as “major development” any project that disturbs half an acre, or adds 5,000 square feet of impervious or vehicle surface. The township calls its rules “stronger” than the state’s.
The 2023 inland flood rule. NJDEP adopted its Inland Flood Protection Rule in July 2023. The township responded with Ordinance 24-1722 on April 18, 2024, “to introduce new rainfall standards and design requirements following NJDEP’s adoption of the Inland Flood Protection Rules.”
The REAL rules. NJDEP’s broader Resilient Environments and Landscapes (“REAL”) rules were adopted on January 20, 2026. Their coastal standards are the core, and Montgomery has no tidal water. On July 17, 2025 the Committee passed a resolution saying “The Township of Montgomery supports the adoption of the REAL Rules as soon as possible” (Res. #25-7-238, consent agenda, 4-0, one member absent). In June 2026 NJDEP proposed extending the “legacy” period, under which complete applications can be reviewed under the old rules, from July 20, 2026 to July 20, 2027. The New Jersey Business & Industry Association praised the delay. The Watershed Institute’s Jim Waltman said, “Every permit issued under outdated, legacy standards puts people and property at greater risk.” In August a law firm reported that the extension had not yet been codified, but that NJDEP had issued guidance to give legacy status to eligible applications received after July 20, 2026. This site has not found the final adoption notice.
Township projects
| Project | What it is | Cost and funding | Status |
|---|---|---|---|
| Stage II plant floodwall | Perimeter floodwall and replacement of worn parts at the Stage II sewage plant | Contract $18,258,600 (2023); final $19,371,076.08 after three change orders (Res. #26-2-85). Bonds of up to $17,000,000 sold to the state Water Bank (Res. #26-3-96) | Completion date extended to March 27, 2026 |
| Detention basin retrofits | Rebuilding two aging basins, at Catbriar Court and Red Fox Run Court, as bioretention basins | KDP Developers, $396,460.22 (Res. #26-6-189); $413,267.22 after a change order (Res. #26-9-250). State grant raised by $177,593 to $606,202.26 (per Headline News) | “Nearing completion” (Sept 17, 2026) |
| 2261 Route 206 demolition and floodplain restoration | Demolishing the old municipal building and restoring the floodplain along Cruser Brook | Demolition: A.B. Kurre, $526,080, final $579,116.92. Engineering: Environmental Resolutions, final $49,492.50 (Res. #26-10-274). A $1,500,000 federal funding request; HUD agreement received June 2025 (per Headline News) | Building down by December 2025; restoration was to “take place in the Spring”; no restoration contract found |
| Hollow Road storm sewers | Part of the 2026 road program: “replacement of certain deteriorating storm sewers at various locations on Hollow Road” | Top Line Construction, $2,198,270.67 for the whole program (Res. #26-9-241, 5-0) | Work began in early October; Hollow Road, Camp Meeting Road and Route 518 closures announced for pipe work |
The Administrator called the basin project “one of the Township’s many approaches to address the Township’s flooding issues.”
The old municipal site. The federal funding request described the purpose as removing “the hazardous flood condition” and returning “the environmentally sensitive land to a natural state.” The Administrator wrote in August 2025 that much of the lower parking lot “is in the floodplain and is prone to flooding,” and that “in past storms, the township lost police vehicles due to rising flood waters.” About 70% of the 31-acre site is restricted by Green Acres. What happens to the rest is still open.
The public works yard in the floodplain
The township’s public works yard is at 12 Harlingen Road. In an August 2025 column the Administrator wrote that NJDEP had long ago required its salt storage to be moved “as that facility lies within the floodplain of a Pike Run tributary.” The column adds that “discussions have been underway for years regarding the relocation of the undersized public works facility, with the goal of moving it out of the floodplain and out of Harlingen’s historic village.”
On March 5, 2026 a concept sketch for the state land in Skillman showed about 25 acres described, in the uncorrected captions, as “an area identified potentially for future public works facility.” The presenter added, “this is very conceptual.” The Montgomery News quoted the Mayor: “DPW [Department of Public Works] is in a flood waters area. That is the reason you are seeing this.” On April 16, 2026 a resident urged the Committee to look at “preliminary plans” for moving the department out of the “flood way” or “flood zone.” The minutes record no response from the Committee.
There is no relocation project, site decision or cost estimate on record. The “preliminary plans” have not been made public. In the meantime, on September 3, 2026, the Committee voted 5-0 to buy a new 24-by-60-foot modular office “for the Township Public Works facility” for $278,697 (Res. #26-9-243). The state-land question is tracked under state lands.
What is not known
- How much the state paid for each Blue Acres home, and when the last two will be demolished.
- What the Lower Millstone draft will propose for Montgomery, what those projects would cost, and when the public comment period will open.
- Whether the state grant agreement for the regional plan has been signed, and what has been reimbursed.
- The Watershed Inventory Report submitted in December 2025, which has not been posted.
- Whether Somerset County and NJDEP have approved the December 2025 stormwater plan.
- The design, cost and schedule of the floodplain restoration at 2261 Route 206, and whether the $1.5 million covers it.
- Whether the Stage II floodwall is finished and certified, and how much FEMA money the plant has received in total.
- Any cost or site for moving the public works yard.
- How many flood-insurance policies are in force in Montgomery today. The township has no class in FEMA’s Community Rating System, the program that can lower premiums for a whole town.
- Whether the REAL legacy extension has been formally adopted.
What residents can do
- Check your flood zone. Look up your address on FEMA’s map at msc.fema.gov. The township’s Flood Search Official is the Township Engineer. Many Ida claims came from outside the mapped high-risk zone, and flood insurance is available there.
- Comment on the regional plan. Watch the Lower Millstone Watershed Plan page for the draft, and send comments on local flooding and drainage problems.
- Speak at a Township Committee meeting. Public comment is open at every regular meeting. The remaining 2026 dates are November 12, December 3 and December 17 (meeting calendar).
- Ask about Blue Acres. Owners of homes that flood repeatedly can contact the NJDEP Blue Acres program.
- Sign up for alerts. The township posts road closures through Nixle.
- Request the records. Through the Township Clerk (OPRA): the Blue Acres MOU and its property list, the Watershed Inventory Report, the state grant agreement for the regional plan, and any concept plans for the public works yard.