TRENTON, N.J., (CBS) — The Coast Guard worked to break ice on the almost frozen solid Delaware River Thursday, as an ice jam continues.

A flash flood watch remain in effect until 8 a.m. Friday for Mercer and northwestern Burlington Counties in New Jersey and  lower Bucks and Philadelphia Counties in Pennsylvania.

The crews of the Coast Guard Cutters Capstan and Cleat worked to help prevent flooding and maintain navigable waterways.

The 65-foot ice-breaking tugs encountered significant ice, up to five feet thick, about three miles south of Trenton, N.J.

“Today they went north in the Delaware River to make sure the navigable channel remained open for transiting commercial traffic,” Lt. Veronica Smith said in a statement.

Route 32 (River Road) remains closed Thursday between Black Rock Road and Trenton Avenue in Lower Makefield Township due to flooding concerns.

“This is the first time the dam has ever been south of Lower Makefield,” says Lower Makefield Police Capt. Tom Roche.

The problem is the water building behind and underneath the icejam.

Chief Kenneth Coluzzi of Lower Makefield Police says, “We like to tell people exactly what to expect but we don’t know ourselves.”He continues, “It’s just frozen solid. The ice has no place to go. The water is still flowing underneath the ice but slowly, and that’s the problem.”

The thawing will ideally come slowly, giving the river time to react and not overreact to flowing again.

The triangular ice chunks seen in the Delaware River will loosen and settle back as liquid this weekend with warmth and rain.

Two residents comment on the possible flooding, “We were thinking about disaster movies and how we would have to run full speed!”

But not likely, the biggest danger Lower Makefield officials are projecting is flooding on River Road.

“If it thaws slowly, we may be okay.” Coluzzi says.

Officials say the time for the River Road to possibly open has been extended to Friday afternoon or evening.

If not, more barricades for roads near the cold as ice Delaware River.

Officials advise motorists not drive around the barricades and to use Black Rock-Yardley/Morrisville and Trenton Avenue as the detour.

Stay with for the latest on this developing story.

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