Ice-breaking operations continued Friday morning on the Kennebec River as U.S. Coast Guard cutters worked their way farther upriver toward Richmond to demolish midwinter ice and ward off further flooding of low-lying areas in and near Augusta.

The National Weather Service’s flood warning issued Thursday was no longer in effect Friday, as the river’s level had fallen to 10.42 feet at 2 p.m. at the U.S. Geological Survey gauge at the Calumet Bridge at Old Fort Western in Augusta. Flood stage is 12 feet, and the river has been dropping since reaching more than 11.8 feet Thursday.

Four Coast Guard icebreakers, including the 140-foot USCGC Penobscot Bay and three 65-foot cutters, were working up to Chop Point in Woolwich, just below Merrymeeting Bay. The boats turned around and cleaned up the river down to Bath before ending the day’s operations.

The three smaller vessels — the Rockland-based USCGC Tackle, the Southwest Harbor-based USCGC Bridle and the South Portland-based USCGC Shackle — made further progress Friday with the help of the larger, heavier icebreaker, said Lt. Matthew Odom, chief of the Coast Guard’s Waterways Management Division in Northern New England.

“They encountered significant ice with thickness upward of 3 to 5 feet in the vicinity of Chop Point,” Odom said. “We should be able to break through the significant ice ridge at Chop Point Saturday and continue up to Richmond Sunday.”

Odom said he does expect the cutters to be on the river Monday and further into next week, but the Coast Guard will determine operations based on daily ice conditions and weather encountered by the cutters.

The Penobscot Bay arrived Thursday on the Kennebec River from the Hudson River in New York and is equipped with a bubbling system under the hull that melts the ice and warms the water.

The Coast Guard received a request a week ago from the Maine Emergency Management Agency to break out the ice on the Kennebec to reduce the risk of further flooding. The depth of the river and low height of the Pearl Harbor Remembrance Bridge linking Gardiner and Randolph limit the Coast Guard’s ability to reach the ice jam, but it will break ice to open up water downriver to improve the river flow, according to Odom.

According to the U.S. Geological Survey, there is about 16 to 18 inches of ice in Richmond just south of the bridge and 8 inches of ice near the center of the channel. In Gardiner, just south of the Cobbosseecontee Stream, there is 18 inches of ice on the left edge and about 14 inches in the middle. The ice is both spots is white and gray and there doesn’t appear to be any slush.

Andy Meyers, the Coast Guard’s chief of prevention for northern New England, said because the ice jam is upriver where the icebreakers can’t reach, it’s difficult to quantify how much of a difference the cutters are making; but every bit of the river that they open helps improve the flow.

The cutters Tackle and Bridle arrived Tuesday on the Kennebec and broke nearly 350 yards of ice Wednesday morning during a shorter-than-expected tidal window.

Chief Petty Officer Lia Chasteen said Wednesday she wasn’t aware of any previous ice-breaking operation on the Kennebec occurring this early in the year. The spring breakout usually happens in late March or early April. It didn’t happen the last two years, however, because warmer weather melted the ice before the Coast Guard was needed to break it.

Chasteen said water was flowing when the Tackle — her vessel — and the Bridle came up the river Tuesday, but they encountered ice and didn’t make it as far as they did Wednesday. She said there was probably 16 inches of solid ice with 2 to 3 inches of snow on top. There was about 6 inches to 1 foot of slush underneath that made it difficult to break, she said.

The 140-foot Penobscot Bay is longer and heavier, which is beneficial for the ramming and backing process, Chasteen said. Ramming and backing is a process in which the cutters go full speed toward the ice and use the weight of the cutter to smash the ice under the hull.

Jason Pafundi — 621-5663

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Twitter: @jasonpafundiKJ