Williamsburg developing action plan to deal with future flood threats

Jim Czach, project manager with VHB who has worked with the town of Williamsburg for engineering and design aspects of flood resiliency, shows some of his findings to residents on June 7.

Jim Czach, project manager with VHB who has worked with the town of Williamsburg for engineering and design aspects of flood resiliency, shows some of his findings to residents on June 7. STAFF PHOTO/SAMUEL GELINAS

Jim Czach with VHB explains how the 5-foot thick concrete support under the North Street Bridge needs to be refined to allow more water to flow under, instead of over the bridge, during times of heavy rainfall. He explained how water splashed over in 2023.

Jim Czach with VHB explains how the 5-foot thick concrete support under the North Street Bridge needs to be refined to allow more water to flow under, instead of over the bridge, during times of heavy rainfall. He explained how water splashed over in 2023. STAFF PHOTO/SAMUEL GELINAS

On the left is a model of what the impacts of flooding could be like in 2070 after 11 inches of rain in a 24-hour period, with impacted areas shown in blue. At the right is the current expectations of impacted areas during an almost 8-inch rain event in a 24-hour period.

On the left is a model of what the impacts of flooding could be like in 2070 after 11 inches of rain in a 24-hour period, with impacted areas shown in blue. At the right is the current expectations of impacted areas during an almost 8-inch rain event in a 24-hour period. STAFF PHOTO/SAMUEL GELINAS

A rendering of what the town would look like with 11 inches of rain in a 24-hour period.

A rendering of what the town would look like with 11 inches of rain in a 24-hour period. STAFF PHOTO/SAMUEL GELINAS

Gaby Immerman, Smith College professor and member of Hilltown Land Trust, speaks with Williamsburg residents about flood resiliency  on Saturday, June 7, in the Meekins Library.

Gaby Immerman, Smith College professor and member of Hilltown Land Trust, speaks with Williamsburg residents about flood resiliency on Saturday, June 7, in the Meekins Library. STAFF PHOTO/SAMUEL GELINAS

Gaby Immerman speaks about flood resilience in Williamsburg beside a rendering of what floods could look like for the town in as soon as 50 years.

Gaby Immerman speaks about flood resilience in Williamsburg beside a rendering of what floods could look like for the town in as soon as 50 years. STAFF PHOTO/SAMUEL GELINAS

By SAMUEL GELINAS

Staff Writer

Published: 06-16-2025 4:16 PM

WILLIAMSBURG — Bad news for Burgy — heavy rainfall will only become more devastating in the next 50 years. But according to a flood resilience study funded by the state, there are antidotes.

Soon after her election as governor, Maura Healey made a stop in July of 2023 to survey the town’s flooded fields and farms after several inches of rain devastated the countryside, including homes and businesses near the Mill River.

In response, the state awarded the town more than $680,000 in state Municipal Vulnerability Preparedness (MVP) funds to develop an action plan to minimize damages from a future deluge, and undertook a study of the Mill River watershed.

Two years later, on the rainy Saturday morning of June 7, several residents came out to see some results of the study in Meekins Library, with visuals and graphs set up by members of the Hilltown Land Trust, which spearheads conservation efforts in the town.

Those involved in the multiple-year study fleshed out some of its findings, including potential enhancements to building codes, recommended infrastructure upgrades, and highlighted the importance of forests to mitigate the impacts of flooding.

A full report is expected, most likely by the fall, on ways the town can develop sustainable strategies, according to Sarah Welch, community engagement coordinator with Hilltown Land Trust.

Findings

Among the bad news for Williamsburg, which is obviously already prone to flooding, is that climate experts predict more intense rain events — and shorter events with higher rain totals — in the years ahead.

Gaby Immerman, a Smith College professor who is on the board of Hilltown Land Trust, spoke about a statistical probability called an “100-year flood,” or a base flood.

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Despite it’s name, the concept actually has nothing to do with 100 years. Rather, it refers to the 1% probability that a given storm could be equaled or exceeded in force over a one year period. In other words, it is a storm so severe that there is only a single percentage point of chance that the storm could be replicated in the same year.

As Immerman said, “there’s a 1 percent chance that you’ll get rainfall of a certain amount in a year.”

At present, a 100-year flood in Williamsburg means an event with 7.8 inches of rainfall. For the year 2071, that amount is projected to be 11 inches.

The firm VHB, engineers and designers out of Springfield who have worked with the town, modeled the river to predict what this would mean for flooding events. A map of the model showed how much more drastically blue the map becomes in the 2070s, representing increased threats to areas that will become “inundated” in the event of such a flood.

Jim Czach, VHB project manager who spoke with residents in the library, pointed out some of the areas most adversely impacted by a potential flood on the map produced.

“You can see Route 9 and properties along there. It’s quite a bit of flooding,” he said.

In response, VHB suggested four infrastructure projects to lessen the town’s vulnerability. These include:

■Replacing the North Main Street Bridge. The bridge is currently supported by a concrete pad 5 feet in height. By making it skinnier, and elevating it, more water will be able to freely flow underneath it, unlike in 2023 when water was building up and shooting over the bridge.

■Installing a flood wall at O’Briens Auto Works. The part of O’Briens along the river is prone to flooding. A 4-foot flood wall on the bank is prescribed to avoid flooding on the property and Route 9.

■Constructing a berm near Cumberland Farms. A berm, or sod wall, would soak up excess water.

■Replace the undersized culvert under Route 9 that carries the Joe Wright Brook.

Aside from infrastructure, nature is able to do some of the heavy lifting to help alleviate a flood as well.

Immerman explained how forest health is important for resilience, because, “Forests are like sponges that hold water” she said, adding, “It is important to help the watershed catch and hold water so the water is not sheeting down into the rivers quickly.”

A big part of “catching water” will be done by the former Beaverbrook Golf Course, which is being rewilded into a conservation space by the Trustees of Reservations and Hilltown Land Trust beginning this summer.

When the official outcome of the study of the watershed is released, it will also recommend regulatory changes, for instance looking into the town’s building codes, wetland bylaws, and what is allowed to be done near rivers.

Samuel Gelinas can be reached at sgelinas@gazettenet.com.