Brookhaven Town on Monday announced an $8.6 million project to rebuild a pair of deteriorated jetties at Mount Sinai Harbor.

The protective jetties have collapsed over time with the seaward ends being submerged underwater, Brookhaven Town Supervisor Edward P. Romaine said.

Brookhaven will pay $5.6 million to help cover the costs of repairs, which include building a new base and adding rocks, but the town will be aided by a $3 million state grant, Romaine announced Monday during a news conference at the Mount Sinai Yacht Club.

The yearlong project will start in 2017 so that it won’t interfere with the current boating season.

The jetties are at the mouth of the Mount Sinai Harbor.

Over the years, the rocks compiling the jetties have collapsed, enabling sand to pass through. Worse, town officials fear police and fire vessels along with fishing and lobster boats may crash into the damaged jetties while traveling through a navigational channel that leads to Long Island Sound.

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“We’re talking about lives here,” said Sen. Kenneth LaValle (R-Port Jefferson) at the news conference.

He said boaters expect to be able to enter and exit the harbor safely.

Ralph Davenport, owner of Ralph’s Fishing Station, agreed the harbor has become dangerous for boaters in recent years.

“A lot of people are getting stuck. If you’re unfamiliar, you’ll crash,” he said.

Town Councilwoman Jane Bonner said she first looked into replacing the piers in 2011 when she invited the U.S. Army Corps of Engineers to inspect it.

“It truly evolved from there,” Bonner said.