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Winter storm could bring fall flooding

Forecasted heavy snow this week could raise reservoir and river levels and damage trees.

Fall Colors
Red maples leaves are backlit with the Tuesday sun in Jamestown. Fall color viewing may be cut short this year with the predicted snow accumulations for this week. John M. Steiner / The Sun

The amount of snow that will fall in the next few days is just one of the variables that is part of the mix for potential fall flooding in the Jamestown area, said Jerry Bergquist, Stutsman County emergency manager.

"Even with all the variables," he said, "there aren't any scenarios that are close to good."

The National Weather Service issued a winter storm watch for much of western and central North Dakota including the Jamestown area for Wednesday night through Thursday night. The watch indicates 6 to 10 inches of snow is possible along with strong winds during the storm.

Adam Jones, a meteorologist with the NWS in Bismarck, said the moisture in the storm could be the equivalent of 1 to 3 inches of rain.

"Most of it as snow," Jones said. "It will stick around through the weekend and then warm up."

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Even normal temperatures of about 62 degrees for a high and 35 degrees for a low would melt off much of the snow next week increasing runoff into local streams and the Jamestown and Pipestem reservoirs.

Pipestem Reservoir is currently at 1,460.2 feet above sea level or about 17.7 feet above the base of its flood control level. Officials with the U.S. Army Corps of Engineers increased the releases from Pipestem Dam from 600 cubic feet per second to 700 cfs on Monday with the intent of lowering the reservoir to the flood control level by Nov. 1.

James Dixon, dam manager for the corps, said the releases will remain at 700 cfs for the next few days until there is an assessment of how the potential snowstorm could affect the water levels. An increase to 800 cfs is possible on Friday.

Releases from Jamestown Dam continue at 600 cfs although the amount of water flowing into the reservoir exceeds the releases.

"Were still going up a quarter of a foot per day," said Ken Lake, project manager for the U.S. Bureau of Reclamation which owns Jamestown Dam.

Lake said the location of any heavy snow will affect the timing of reservoir level increases at Jamestown Dam.

"If the moisture is near Jamestown, the effects are immediate," he said. "If the precipitation is near the headwaters (near Harvey, N.D.) it would take two to three weeks for it to reach the Jamestown Dam."

The combined releases of 1,300 cfs, or 1,400 cfs if the releases from Pipestem Dam increase on Friday is sustainable although sewage lift stations are a concern, said Travis Dillman, Jamestown city engineer with Interstate Engineering.

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Lift Station No. 9, located in the Jamestown Business Center parking lot, is currently running about three times as much as normal. The lift station handles sewage from the older portion of north Jamestown near the river.

The main lift station which handles waste from the entire city and is located east of town is running about twice as much as normal.

The lift stations are running more frequently because of the amount of water infiltrating the sewer pipes from the saturated ground.

Dillman said there is no specific level of combined releases that would force officials to take additional flood prevention steps.

Bergquist said the most comparable situation was in August 2011 when summer rains forced combined releases of 2,400 cfs through Jamestown. Some sandbagging in low areas along the river was necessary at that time.

City crews are monitoring the James River on a daily basis, Dillman said. Homeowners should also monitor sump pumps and basements for water infiltration in their own homes.

Along with possible flooding along the river, the winter storm watch brings another danger to the area.

"We're looking at wet snow on top of trees that still have their leaves," Bergquist said. "We could see a lot of tree damage."

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And for farmers, snow could aggravate already too wet harvest conditions.

"The only positive is that it is early enough to melt off," said Alicia Harstad, Stutsman County agent for agriculture and natural resources. "But then we'll have more sloppy conditions in the field."

Harstad said large temperature swings, especially with wet weather, can also be hard on livestock.

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