HARTFORD (AP) — The small dam on Bill Rutan's Stonington property began failing in 2010 after two major storms. Afterward, with help from a conservation group, he decided it was better to simply remove it than spend tens of thousands of dollars trying to repair it.

It was among thousands of dams in the state built more than 100 years ago to power mills or small factories, or to create water supplies for farms.

Usually made of earth or stone, the vast majority are on private property and many no longer serve the purpose for which they were built. Some are crumbling or overgrown with vegetation, or have been compromised by tree roots.

"These are time bombs," Rutan said. "And unfortunately, I don't think most owners know what they are dealing with."

In most cases, a dam's failure would mean minimal damage, minor flooding or the loss of a small pond. But The Associated Press has identified 12 Connecticut dams in poor condition that have been rated high hazard because of the potential for loss of life should they fail.

A more than two-year AP investigation found at least 1,680 such dams across the country.

"We don't think we have any high-hazard dams in the state that are ready to actually fail," said Charles Lee, the assistant director for water planning management at the state Department of Energy and Environmental Protection. "We know we have a lot of dams that need a lot of work and there is a very big dollar cost to that. So if that's considered a major infrastructure problem, that needs to be considered."

All dams must be inspected periodically. High-hazard dams must be inspected every two years, a task no longer performed by the state.

A 2013 change in state law put that responsibility, at a cost of about $2,500 per inspection, with the property owner. They also must file an engineering report with the state, devise an emergency action plan to be followed should the dam fail and pay for any needed repair work.

The process of repairing a dam can take years of permitting and can cost hundreds of thousands of dollars, Lee said.

"Not every landowner can handle this," said state Sen. Cathy Osten, D-Sprague. "This is something that is going to rear its ugly head over and over again in the coming years."

Osten said she expects legislation will be needed to address the potential effects of decaying dams. The first step, she said, is passing a bill that would require property owners to disclose the presence of a dam before selling any land to an unsuspecting buyer.

Rutan said he had no idea how much money he would eventually have to sink into his dam, which was built in the mid-1800s, probably to help power a mill of some type downstream, he said.

Fortunately for him, the Nature Conservancy was interested in helping him with the more than $100,000 cost to remove the dam, restoring a passage upstream for herring. The pond is now a brook.

Removing dams can have many environmental benefits, including releasing sediments and nutrients that should be moving downstream to help protect salt marshes, said Sally Harold, director of river restoration with the Connecticut chapter of the Nature Conservancy.

Dealing with other dams across the state is a challenge. That kind of financial help isn't available for all of them, and yet leaving high-hazard dams to fail is not an option because of safety and liability concerns.

"I feel for the people who have owned these dams, for in some cases generations, and now suddenly are faced with needing hundreds of thousands of dollars for repairs," Rutan said. "This is a problem that's only going to get worse."