Ice clog on Missouri prompts road closure, flood advisory

Ice jamming on the Missouri River south of Cascade has prompted a closure of Sheep Creek Road and a flood advisory.

It's also something to see, said Cody Person, who lives on the river a half-mile downstream from Pelican Point.

"The way that the ice formed, and then we got the foot of snow that fell, the river itself looks almost like a grass hay field," Person said. "You don't know where the river bank stops and the ice starts." 

Over several river miles south of Cascade, the Missouri River is a jumble of backed up ice jutting from the river this way and that, and ice shards are covered by almost a foot of fresh snow.

The jam is causing broken ice to accumulate, and backing up water, said Arin Peters, a senior hydrologist with the National Weather Service in Great Falls.

But flooding isn't the biggest concern at this stage.

"The biggest thing we're concerned about is anybody trying to walk on that unstable ice, which is extremely unsafe," Peters said.

Water temperature in rivers is variable meaning ice could be 3 feet in one location, Peters said, "then you'll hit a warm spot and it will be an inch and you will fall through."

Sheep Creek Road, on the east side of the river across from the Pelican Point fishing access site, was closed by the county last week after the logjam of river ice forced water over the road.

"It's just going to ebb and flow with the weather," said Brian Clifton, Cascade County Public Works director. "We're just keeping an eye on it."

The road leads to recreational residences along the river.

"We're not going to be able to open it back up until the ice jam goes down," Clifton said.

The National Weather Service issued a flood advisory until further notice because the ice jamming has caused minor flooding across portions of the region. 

"That's more ice I can remember in the past six years," Mike Bushly, owner of Trout Montana, a fly fishing shop in Cascade, said of the frozen Missouri River.

Cold temperatures and heavy snow has put a damper on fishing, said Bushly.

"I want the chinooks back," said Bushly, referring to the warm winds that have been absent in recent weeks.

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Constriction in river channels is a big factor in ice jams, the Weather Service's Peters said.

"All's it takes is a little bit of accumulation of a few pieces of ice that just keeps building and building and then you have an ice jam," he said. "And it's caused by this extremely cold weather we've had."

Heavy snow and below-zero and single-digit temperatures settled on the region in early February and have refused to lift.

The Missouri River ice jam south of Cascade isn't very tall, and therefore isn't backing up too much water, Peters said.

As long as temperatures stay cold the ice jam probably will remain relatively stable, he added.

When the ice melts the water will be released but the Missouri River has a large channel so Peter says he's not expecting flooding to get too much worse.

"Ice jam season lasts November to March, so we're right in the thick of it," Peters said.

Ice is higher than usual but isn't as high as he's seen it in the past, said Person, the resident who lives along the river.

"We've actually had ice back up over the riverbank and sit on our lawn," Person said.

This year, river back channels have backed up due to the ice jamming and flooded the access to some homes but not the houses, Person said. Those waters have since frozen over.

"And it's been fun to watch the animals cross the ice," Person said. "We've seen coyotes and deer and all sorts of things."

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Person thinks the ice has forced some of waterfowl to move to parts of the river with open water or wheat fields. And he suspects that's why he has seen more golden and bald eagles around roosting on telephone poles and pivots. 

"There's more of those than I've ever seen and they're having a heyday on those ducks," Person said.

Kim Schierenbeck, a hydrologic engineer with the U.S. Geological Survey in Helena, was on the bridge crossing the frozen river in Cascade Tuesday afternoon repairing a malfunctioning solar-powered USGS stream flow gauge.

"That's the thing about science," Schierenbeck said. "Sometimes nature has other plans. You never know when there's going to be an ice jam."

The ice jam didn't cause the malfunction, but cold weather was to blame for USGS stream gauge equipment freezing in a well at the Missouri River in Ulm, she said.

"It was reading just perfectly flat," Schierenbeck said of the Ulm stream gauge.