The torrential downpours that pummeled Leominster Monday night damaged a dam in the city, raising concerns it might fail.

As the city quickly worked to shore up the troubled Barrett Park Pond dam, the threat it posed to the community served as a stark reminder of the large number of dams across the state that are in dire need of repair or removal.

On Wednesday, a huge excavator scooped up gravel and spread it across the earthen dam, which is 150 feet long and 15 feet high.

The water topped the dam during Monday night’s deluge and the city decided to evacuate all the homes downhill of it, which temporarily put about 100 people in a shelter.

"If you go up there, it's a nice little pond — but it's got this dam, and we know that the integrity of it is sketchy," Leominster Mayor Dean Mazzarella said at a press briefing.

Built in the 1800s, the Barrett Park Pond dam was assessed to be in poor condition when it was last inspected in 2017. Before the storm, Mazzarella said, the city received a grant toward replacing it, but it only paid for the planning.

“Now we have to file for another grant based on the documents that we have, and hopefully we'll get that grant so that we can completely do over the dam,” he said. “What we're doing now is a temporary fix. It's going to stabilize it and it's good through the storm, but it's not a permanent fix.”

Standing by the dam, Martha Snow Morgan of the Nashua River Watershed Association said when news of the storm hit, she was not surprised to hear there was a problem here.

“There are so many dams around the state, around our watershed, that are aging and threatened by these extreme weather events. And we're worried about that,” Morgan said. “And the dams need to be prioritized by the state. We need to have a really good mapping system that categorizes all these dams and their threats to life and property. And we need to let people know if they're in a flood zone beneath these dams that may fail.”

There are about 3,000 dams in Massachusetts. About 1,300 of them are large enough to be listed in the National Inventory of Dams kept by the U.S. Army Corps of Engineers. Of those, 328 are ranked as having “high hazard potential,” which means that if the dam fails, there will likely be a loss of life or significant damage to homes, buildings, infrastructure. Another 643 dams, including the Barrett Park Pond dam, are rated as a “significant hazard.”

“Many of those dams need to be removed because they're obsolete,” Morgan said. “They're aging. They've long lived past their useful lives for whatever they're used for.”

Morgan said she’s hopeful that a portion of the billions of dollars that were made available under the 2021 federal infrastructure bill will have an impact on removing and improving the state’s dams.

It would be a relief to some Leominster residents, as the Barrett Park Pond dam is all that stands between the nine-acre body of water and a busy residential neighborhood below.

After water topped the dam on Monday night, it rushed downhill in what’s usually a pretty calm stream, forming a sinkhole on Pleasant Street, destroying the street and washing out all the soil around one house and leaving its foundation exposed.

Leominster Sinkhole
A sinkhole opened up on Pleasant Street in Leominster
Craig LeMoult GBH News

Lenny Valarezo lives just up the hill from where Pleasant Street collapsed.

“By the time that I stepped out and took a look at it, I saw water start rushing through it, just crazy flooding,” Valarezo recounted. “I had never seen anything like that before.”

Since that night, Valarezo said he's thought a lot more than usual about that nearby dam.

“That's all I kept hearing about is, ‘The dam might break, the dam might break,’” he remembered. “And my understanding is that residents have been calling for that to get fixed for a while now, and it just never happened. So I don't know what the story is there. But I really, really hope they prioritize that now and get that fixed because, yeah, that was pretty scary.”