As another wave of wintry weather barrels towards Metro Vancouver, first responders are already expecting rescues and close calls from lingering ice left over from the last blast of sub-zero temperatures.

Several lakes have a crust of ice on top, which looks strong enough to stand on but barely supports the weight of an animal, let alone a person.

Just last week, a woman jumped into Surrey's Serpentine River after her dog and a friend's dog ran after a bird and crashed through the ice.

"You're better off calling firefighters because we're able to get the animal out safely without complicating things by having to get the owner out as well," explained Burnaby Fire Capt. Dan Monk. "There's been many calls (over the years) where several people go trying to do the right thing and they all end up in the water."

On Thursday morning, Monk led another round of training for Burnaby firefighters on Deer Lake, where the ice is barely three centimetres thick, well short of what's considered safe.

New recruits who walked onto the ice to be "rescued" fell through the crust with a couple of jumps.

"Your heart kind of drops a little bit, especially when they intentionally make you jump through and you see all the cracks forming under you," said Vaitua Haddou. He was wearing insulated, waterproof gear and avoided getting his face and head wet throughout the rescue scenarios.

Kevin Galick was one of the rescuers going after Haddou and another recruit using floating throw-bags on ropes, floating rescue collars and inflatable watercraft they'd use for genuine rescues.

"It's pretty hard because the ice is so thin," Gallick said.

Rescuers say surviving the initial fall into the water is critical: the initial shock of the frigid temperatures results in cold water immersion, causing people to involuntarily gasp and gulp water as they flail. Drowning often occurs within the first minute due to that reaction.

After that, Monk says the second phase sets in where the initial panic wears off enough that some people are able to scramble onto the ice on their belly and get to safety. Animals are much more likely to do this, thanks to buoyant fur and claws, but people have a tougher time. If they can't, rescuers suggest leaving your arms on top of the ice so they freeze to the surface, keeping you above water as your strength fails and allowing rescuers a better chance of finding you.

"Usually if a rescue isn't done in that first limited time frame -- if that person is by themselves, they don't have someone to call 911 -- there's no survival," said Monk.

With ice lingering on many of the area's lakes, first responders across Metro Vancouver are urging people to stay off of ice that's likely to thin to support a person's weight and keep dogs on a leash; many rescues begin with animals running onto the surface.

"We don't get ice all that often but we have to train for it all the time so we're competent for it when we do get the call."