YELLOWKNIFE - Norm McBride says he first realized a snowmobiler had plunged into the lake when a professional diver came calling.

"A Ski-Doo went into the water, it went into 24 feet of water," said McBride, manager for NWT Power Corporation's Jackfish Lake diesel plant.

McBride is referring to a stretch of open water on Jackfish Lake behind the power plant. The open water and surrounding thin ice is caused by warm water from the plant pumped back into the lake.

"It's used for cooling of the diesel engines," said McBride.

He said that snowmobilers have been skipping the open water across one frozen patch of ice to another.

This phenomenon is known as 'puddle jumping' and can be quite dangerous.

The snowmobiler who fell into the open water managed to get out and leave with a snowmobiling friend who was with him, McBride guessed.

"It's dangerous, especially if they go through at night," McBride said, which he said is the most popular time to jump Jackfish's puddle.

Deputy fire chief Chucker Dewar said the fire department has heard stories of people puddle-jumping at Jackfish Lake, and has investigated the site.

"It's considered a high risk behaviour," said Dewar.

"People are really tossing a coin where it concerns their safety or that of others."

Currently, the NWT Power Corporation has a flashing yellow sign near the sledding trail at the other side of the lake warning people of the thin ice.

"We've put a rope around the area and we put signs up," he said.

McBride said that they also called city bylaw enforcement on the issue, but were told that puddle-jumping isn't against the law.

RCMP Const. Roxanne Dreilich said there is little on the books they can use to charge puddle-jumpers either.

"As far as legality, to get into that we'd be looking at gross negligence or reckless driving," said Dreilich.

Doug Gillard, manager of municipal enforcement, said he can't stop people from puddle-jumping but there is a 35km/hr speed limit on Jackfish Lake.

He said snowmobile-riding bylaw officers do periodic patrols on Jackfish Lake with radar guns. He said snowmobilers have been ticketed there in the past.

Bruce Hewlko, a spokesperson for the Great Slave Snowmobiling Association, said their organization promotes safe riding as opposed to "thrill seeking,' which is what he calls puddle jumpers.

"It's not safe for the snowmobiler."

Hewlko said a lot of bad things can happen when puddle jumping. The snowmobile's engine can stall, for instance.

In that scenario, the snowmobile will sink and the rider's suit will become weighed down with cold water.

"It's like trying to swim with a frozen snowsuit," said Hewlko.

He said he's gone through the ice only once, and that was from thin ice near shore and not from puddle jumping.

He described falling into the ice as "very cold."

Hewlko said a safer alternative to puddle jumping is entering the drag race competitions that happen across the NWT during the winter.

"That's a very good alternative because it's in a controlled environment," he said.

And even if a puddle jumper is doing it with friends, Hewlko posed this question:

"Do you know that your friend will jump in to save you?"

McBride said he is aware of three snowmobiles going through the ice since he started working at Jackfish six years ago, but thinks the number could be higher.

"It's not on our property, it's a lake that we utilize," McBride said.

Despite limits on what they can do, the power plant is still looking for a way to deter puddle jumping next year.

McBride said he is thinking of putting up a flotation barrier, so that so when the ice melts it won't sink to the bottom.

But he's not sure if that will ultimately solve the problem.

"I wish we could come up with a solution."