Clouds cast shadows on the frozen surface of Moosehead Lake on Feb. 10, 2021, and are seen from an overlook on Mount Kineo. Credit: Aislinn Sarnacki / BDN

Two snowmobiles went through the ice in separate locations on Moosehead Lake Thursday due to pressure ridges created by fluctuating temperatures.

One sled broke through the ice near Burnt Jacket on the east side of the lake. The other occurred in the area of Farm Island, north of Mt. Kineo State Park on the west shore. The drivers of the snowmobiles were not seriously injured.

“Both sleds did go through the ice and into the lake,” Warden Sgt. Bill Chandler said. “Fortunately, they were in shallower areas. One of the sleds has already been removed and they’re working on the other one.”

Social media posts on Thursday also pointed to a dangerous area of open water on a marked snowmobile trail that crosses Moosehead Lake near the boat launch in Rockwood. The Warden Service is actively assisting in that location.

“One of our wardens is working with the snowmobile club to try to make that the best situation that we can, maybe to reroute the trail a short distance around that,” Chandler said.

It’s a bad year for pressure ridges at Moosehead Lake, which are creating treacherous conditions for snowmobilers and others enjoying winter activities on the ice. The conditions are prompting concerns among those who use the lake and the law enforcement officials who monitor snowmobiling, fishing and other activities.

Anyone who plans to be on Moosehead Lake should be aware of the rapidly changing ice conditions, Chandler said.

“The pressure ridges on the lake are bad this year,” Chandler said. “They’re showing up in some different areas that they haven’t always been.”

Pressure ridges are formed by temperature changes that cause the ice to expand and contract. That sets the stage for a collision between the two floating sheets of ice on either side of the crack, which can force the ice up onto the other sheet.

Pressure ridges can be several feet high, posing danger for snowmobilers who might be speeding or riding at night when visibility is reduced.

Thursday’s warmer temperatures created significant melting that worsened the problem.

“They seem to be flattening out a little bit and maybe even separating in places,” Chandler said of the ridges. “We’re seeing a lot of standing water in and around where the pressure ridges are.”

Things could get worse because of changing weather conditions. After last Saturday’s snowstorm and a stretch of frigid weather, the temperature in Greenville approached 40 degrees on Thursday.

The quick thaw was expected to be followed by another significant storm lasting into Friday night. That likely will further complicate the conditions at Moosehead and elsewhere by lowering visibility and hiding trouble spots.

“Chances are good we’re going to see slush conditions on the lake and it’s also going to add to these pressure ridges. It’ll make them harder to see as well,” Chandler said.

Anyone who plans to be on the lake is being urged to take precautions to avoid pressure ridges and areas of standing or open water.

Chandler said local knowledge is often the best source of information. Snowmobile clubs, bait shops, restaurants and gas stations all are likely to be aware of dangerous areas.

Snowmobilers should remain informed, stay on marked trails and slow down, especially if riding at night.

“If you don’t see a track going in a certain area, if you’re not familiar with the lake, don’t go there,” Chandler said. “Be mindful that there are areas of the lake that are bad all times of the year.”

Pete graduated from Bangor High School in 1980 and earned a B.S. in Journalism (Advertising) from the University of Maine in 1986. He grew up fishing at his family's camp on Sebago Lake but didn't take...