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Flooding and Stormwater in Hillsborough: New Flood Maps, a New Ordinance, and the Work Since Ida
FEMA's revised flood maps for Hillsborough take effect on November 13, 2026, the date FEMA set in an August 2026 Federal Register notice. Ordinance 2026-10, which adopts the maps and rewrites the township's flood rules, has its hearing on November 10. Since Ida in 2021 the township has rebuilt a damaged basin, joined the state's Blue Acres buyout program, adopted a long-range drainage plan and started a state-required watershed plan.
What is happening
Hillsborough has no coast, so its flood risk comes from rivers and streams: the Millstone River along River Road and the Studdiford bridge, the Raritan and its South Branch, and Royce Brook and its tributaries. The remnants of Hurricane Ida, on September 1–2, 2021, are the storm the township’s records keep coming back to. Ida damaged a stormwater basin behind Harvard Way, led owners of flooded homes to apply for state buyouts, and changed part of FEMA’s flood map.
The next step is a deadline. FEMA’s revised Flood Insurance Rate Maps for Hillsborough take effect on November 13, 2026. FEMA set that date in its final flood hazard determination, published in the Federal Register on August 6, 2026, and the township’s draft ordinance uses it. (FEMA’s August 2025 public notice had said only “Fall 2026,” subject to change.) Before the maps take effect, the township must adopt a floodplain ordinance that uses them.
The new flood maps
What changed. FEMA released revised preliminary maps for Hillsborough, Bedminster, Branchburg and Union Township (Hunterdon County) on March 7, 2025. In March 2025 the Committee was told that the change in Hillsborough covered map panel 137, which includes parts of River Road by the Studdiford bridge, with a minor revised flood area due to Tropical Storm Ida. Comments were due April 7. A 90-day appeal period opened on August 21, 2025.
The draft ordinance lists every panel that covers the township. Only two get new maps:
| Panel | Effective date | Edition |
|---|---|---|
| 34035C0137 | November 13, 2026 | F (new) |
| 34035C0141 | November 13, 2026 | F (new) |
| 34035C0163, 0164, 0252, 0253 | November 4, 2016 | F |
| All other panels | September 28, 2007 | E |
What it does not tell you. How many homes move into or out of the high-risk flood zone is not in any township record. FEMA’s maps let you check your own address (see below).
Ordinance 2026-10
The draft ordinance is titled “An Ordinance Repealing And Replacing Chapter 172 ‘Flood Damage Prevention’ … To Maintain Compliance And Participation In The National Flood Insurance Program.” Hillsborough joined that program on March 2, 1981.
What the draft does:
- Adopts the new maps. It adopts the Somerset County Flood Insurance Study and the maps “dated November 13, 2026.”
- Names a Floodplain Administrator. The Township Engineer takes the job, administering flood permits and interpreting the rules, working with the Construction Official.
- Points to the state’s wider rules. The draft says New Jersey’s Flood Hazard Area Control Act “regulates unstudied flood hazard areas in watersheds measuring 50 acres or greater in size and most riparian zones,” so “the regulated flood hazard area in New Jersey may be more expansive and more restrictive than the FEMA Special Flood Hazard Area.”
Where it stands. The ordinance was on the October 27, 2026 agenda for introduction. That meeting’s minutes are not yet posted, so the introduction vote is not confirmed. The same agenda set a special Township Committee meeting on November 10, 2026, at 6:30 pm for the public hearing (R-335-2026), three days before the maps take effect. In Hillsborough, the public may comment at the hearing, not at introduction.
The work since Ida
| Project | What happened | Status |
|---|---|---|
| Harvard Way basin | The detention basin behind Harvard Way (the Hillsborough Campus) was damaged by Ida. In June 2025 the Committee was told the NJDEP permit had taken two years and that work could not start until October 2025 because of bat-habitat restrictions | Reported reconstructed to its original design on December 9, 2025 |
| Blue Acres buyouts | On June 24, 2025 the Committee approved an agreement with NJDEP’s Blue Acres program; the township maintains the lots after the state buys and demolishes flooded homes. The Committee was told 11 owners had applied and that FEMA and Blue Acres were looking at homes along Dukes Parkway East and Kimberly Road | How many sales have closed is not on record |
| County hazard plan | The Committee adopted the 2025 Somerset County Hazard Mitigation Plan on June 24, 2025 | Adopted |
| Long-range drainage plan | On August 12, 2025 the Committee adopted a resolution “Creating and Implementing a Long-Range Plan to Address Drainage Issues.” It calls for a Watershed Assessment and a Watershed Improvement Plan listing projects, a schedule, costs and funding, updated every two years | Plan not yet published |
| Watershed inventory | The same night the Committee hired Pennoni for a Watershed Inventory Report, Phase I, for up to $134,000, “as part of the NJDEP requirements,” plus mapping of the storm sewer system | No report posted |
| Willow Road | Application for a $2,000 Sustainable Jersey/PSEG grant for a “Willow Road Green Infrastructure Feasibility Study” (R-98-2026, February 24, 2026) | Award not on record |
| Fox Chase Pond | In May 2026 a resident told the Committee that NJDEP funds for the pond’s restoration “have to be used by December 31, 2026.” The June 23 agenda carried a contract with West Jersey Lawn Care, up to $41,600, for excavation for the Fox Chase Pond Shoreline Restoration Project, with the Rutgers Cooperative Extension Water Resources Program (R-210-2026) | June 23 minutes not yet posted; vote not confirmed |
| PROTECT planning grant | The Planning Board’s October 8, 2026 agenda included a letter of support for the township’s “Green Hills Transportation Resilience & Emergency Access Planning Project,” under the FY24–FY26 PROTECT planning grant program | Amount and outcome not on record |
Why the watershed plan. The township holds a state “Tier A” stormwater permit (NJPDES NJG0153231). That permit requires a Watershed Improvement Plan. The August 2025 resolution also cites “scarce resource immunity” under the state’s Tort Claims Act (N.J.S.A. 59:2-3).
Rules for property owners. In August 2026 the Engineering Department reminded residents that sump-pump lines must not discharge onto the street in new construction, and that “any line causing hazardous street flooding or icing must be relocated.” Businesses and homeowners associations “must maintain their private stormwater systems” and file an annual certification with the Engineering Department.
What is not known
- Whether Ordinance 2026-10 was introduced on October 27, and whether it will be adopted on November 10, before the maps take effect.
- How many properties change flood zone under the two new panels.
- How many of the 11 Blue Acres applicants have sold, and for how much.
- Whether the Pennoni watershed report is finished, and what projects the drainage plan will list.
- Whether the Fox Chase Pond work was approved and will be done by the grant’s December 31, 2026 deadline, and the name and size of that grant.
What residents can do
- Speak at the hearing. Ordinance 2026-10 is scheduled for its public hearing at a special Township Committee meeting on Tuesday, November 10, 2026, at 6:30 pm, in the Peter J. Biondi Municipal Building, 379 South Branch Road. Introduced ordinances can also take online comment on Engage Hillsborough.
- Check your flood zone. Look up your address on FEMA’s map at msc.fema.gov. The township’s Engineering Department posts flood insurance information and the flood zone permit.
- Ask about Blue Acres. Owners of homes that flood repeatedly can read the township’s Blue Acres page.
- Request the records. Through the Township Clerk (OPRA): the Pennoni Watershed Inventory Report, the Blue Acres agreement, and the Fox Chase Pond grant agreement.