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Storm runoff fills Fresno

 


Much of Montana is seeing rampant flooding because of the five-day rain and snowstorm in the past week, but Fresno Dam succeeded in serving its dual purpose.

The dam, built in the 1930s by the federal Bureau of Reclamation to store water for irrigation and provide flood control, kept billions of gallons of storm water from rushing down the Milk River in the last few days.

The low level of Fresno Reservoir due to the drought was actually a benefit, said Tim Felchle, hydrologist for the Bureau of Reclamation. It permitted Fresno to stop a lot of extra water.

"We were pretty fortunate and pretty happy to have the amount of space we had in there with that storm hitting," he said Thursday.

A chance of flooding remains for the next several days, depending on how quickly snow melts in the mountains and whether it rains again.

"The two unknowns are how fast the snow melts and how much rain is associated with it," Roy Kaiser of the U.S. Department of Agriculture's Natural Resource Conservation Service said today.

The National Weather Service doesn't expect major precipitation or snowmelt, meteorologist Don Emanual said, although that could change rapidly.

The Weather Service expects warmer and dryer weather for the next few days, with cool nights, and cooler weather and showers early next week.

A five-day rainstorm dumped from 3 to 7 inches of rain on the Hi-Line between Havre and Chester. That, plus runoff from even heavier rain and snow in the Rockies and Glacier County, caused streams and rivers to rise, Kaiser said.

The dam at Fresno was able to catch the runoff, and since its water level was so low, keep it from flooding the valley downstream.

If the dam hadn't been there, or if the reservoir had been too full to hold it, thousands of acre-feet of water would have flooded the valley, Felchle said.

Clay Vincent, sanitarian and planner for Hill County, said today that a lot more water could have hit the reservoir if the ground hadn't been so dry again, because of the drought.

A dam maintained by the Sage Creek Hutterite Colony in Liberty County was in danger of giving way, as runoff from the 7 inches of precipitation in the Sweet Grass Hills arrived, Vincent said. Members of the colony were able to save the dam, but water up to 2 feet high was flowing over it.

The water rushed down Sage Creek, which empties into Big Sandy Creek and then into the Milk a few miles downstream from Fresno.

Shawn Norick of the Liberty County road department said flooding has caused major damage to infrastructure in the county, with some roads shut down and others limited to one-lane traffic. But it could have been a lot worse, he added.

The rain turned to snow in the Sweet Grass Hills, slowing the runoff down considerably, Norick said.

"If it hadn't snowed, we would have had a lot more damage," he said.

The drought conditions helped prevent damage downstream, as empty ponds and reservoirs filled with runoff.

"We took the brunt of it," Norick said. "It started right in the hills. The farther it went, it was filling reservoirs. That really slowed it down."

The flooding topped roads and bridges, but the only bridge severely damaged in Hill County was one north of Rudyard, which caught fire Thursday afternoon when someone was burning weeds, Vincent said.

Other bridges, like one north of Inverness and the Cottonwood Bridge that crosses the north edge of Fresno, will have to be inspected and may need work or reconstruction, he said.

The Inverness bridge was closed this morning. County Commissioner Kathy Bessette was uncertain about the status of the Rudyard bridge.

The water going into Fresno peaked at 11,000 cubic feet per second Thursday. Vincent said it has dropped to about 10,000 cubic feet per second today.

The inflow was about 1,186 cubic feet per second June 7, the day before the storm began.

The reservoir's water level has gone from about 42 percent of average last Friday to about 117 percent of average Thursday. The water stored in the reservoir has jumped from 27,415 acre-feet last Friday to 75,113 acre-feet Thursday, and the water's elevation at the dam has climbed from about 2,553 feet to more than 2,571 feet Thursday.

An acre-foot is more than 43,000 gallons, or enough water to cover one acre with a foot of water.

Scott Guenthner of the Bureau of Reclamation said today that releases from Fresno have been increased, from about 700 cubic feet per second Wednesday to about 1,500 cubic feet per second today.

"We do expect Fresno to fill later today or early tomorrow. Once it's filled, then water will start going over the spillway," he said.

Nora Phelps of the Bureau of Reclamation said the last time Fresno was full, with water going over the spillway, was 1997.

The water coming into the river will give the bureau the chance to fill the entire irrigation system the Milk supplies for the first time in several years, Felchle said.

"I think the irrigators will probably have smiling faces," he said.

Nelson Reservoir near Malta still needs to have water released to it, and Lake Sherburne, which supplies the St. Mary Diversion to provide irrigation water to the Milk, still isn't full. But the entire system could be full soon.

It will be nice to have some reserves again, Felchle said.

"I think going into the fall we'll have some carryover storage," he said.

The only concern is if another massive storm hits the area with no room in the reservoir, Felchle said.

"If we have another rain like that while Fresno is full, that's going to put 16,000 (acre-feet) down the Milk," he said.

 

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