The Maine Warden Service dive team uses side-scan sonar off the front of its boat while searching the Androscoggin River on Friday for the missing 5-year-old boy. The river has risen dramatically since the boy fell into the river Tuesday evening. Daryn Slover/Sun Journal

LEWISTON — Divers have concluded their search on the Androscoggin River for a 5-year-old boy who plunged into the chilly waters Tuesday evening.

“Diver search options for the river have been exhausted,” said Auburn Deputy Chief Jason Moen in an email Friday afternoon.

He said the Warden Service will continue with boat patrols and aircraft patrols as weather permits.

He also said the boy’s 9-year-old brother, who had jumped in after his brother, is now in stable condition at Maine Medical Center in Portland.

Officials from the Maine Warden Service had said Friday that the Androscoggin River’s increasingly swift currents were hampering their search in the recovery of the 5-year-old boy.

Conditions on the river made it too dangerous for divers to search the bottom, so the dive team deployed sonar equipment to aid in their search Friday, Lt. Adam Gormley said.

“Obviously, at day three, we’re not giving up,” he said. “We still want to locate this little boy. But it’s environmentally challenging.”

The river’s water volume is three times greater than it was when the search began, Gormley said.

The high level of the Androscoggin River is presenting a “ton of challenges” for the Maine Warden Service dive team, said Sgt. Bruce Loring. Daryn Slover/Sun Journal

“That is ripping,” Sgt. Bruce Loring said, pointing to chunks of ice in the river moving at 3 to 4 mph.

Dam operators upriver have worked with divers try to regulate water flow.

Three boats were launched Friday off Lincoln Street, along with seven divers.

The search will continue from the spot where the boy entered the river and move downriver about one mile, said Loring, who is in charge of the dive team.

If the sonar indicates an object under the water consistent with the boy’s body, the spot will be marked with a buoy and divers will search that area as water conditions allow, he said.

“At this point, it’s undiveable,” Loring said. In addition to the strong current, there was “zero visibility” on the bottom, he said. “You literally cannot see your hand in  front of your face.”

The sonar deployed on the boat Friday sends out sound waves that are read by a laptop computer on board the boat.

“That’s our best tool right now,” he said.

Sgt. Bruce Loring, far right, and other members of the Maine Warden Service dive team hook up side scan sonar to the front of their dive boat at the boat launch on Lincoln Street in Lewiston on Friday morning. Daryn Slover/Sun Journal

Aircraft and boats have scoured the surface of the river and banks for any sign of the boy all the way to the first dam in Lisbon, Gormley said. Pilots have flown as far as Merrymeeting Bay.

“There’s no way we can tell 100 percent that he went right here or that night he stayed enough and floated all the way down,” Gormley said. “In the spring, there’s just so much water, it’s just a free flow right to the ocean. We’re hoping that’s not the case.”

Gormley urged the public to exercise extreme caution when approaching the river and get close to the water to look. If they see something, they should call 911.

“This water’s cold, it’s moving fast and it’s unpredictable,” he said. “The banks are muddy, they’re steep and they’re full of debris. We don’t need another fatality.”

In 45-degree water, hypothermia is likely to set in within about 10 or 15 minutes after exposure, Gormley said. “They’re in trouble, big trouble.”

If dive efforts were suspended at the end of the day on Friday, Gormley said the search would continue by conducting constant dam checks, routine boat patrols and frequent flights up and down the river.

“By far, we’re not giving up,” he said. “I guess that’s the biggest message.”

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