Water elevation in flood storage at Jamestown Reservoir

JAMESTOWN – The water elevation is nearly at the top of Jamestown Reservoir's conservation pool, and the U.S. Army Corps of Engineers started releasing water on Wednesday, March 29, from the Jamestown Dam.

A 13-cubic-feet-per-second release was initiated at 10:15 a.m. Wednesday, said Nathan Kraft, a civil engineer for the U.S. Bureau of Reclamation’s Dakotas area office, in an email.

As of Wednesday afternoon, Jamestown Reservoir is 0.33 feet into the flood storage at 1,431.33 feet above mean sea level as of March 27, according to the daily reservoir data. As of Tuesday, March 28, the reservoir was 99.2% full, and the reservoir flood control pool was at zero.

“It’s pretty early, maybe the earliest time of the year in March, to have Jamestown Reservoir in flood storage,” said Bob Martin, part-time assistant Pipestem Dam manager for the Corps of Engineers. “It’s kind of unusual (that) it just kept climbing a little bit pretty much all winter.”

The water elevation at Pipestem Reservoir is at 1,442.25 feet AMSL as of Tuesday, March 28, he said. The conservation pool at Pipestem Reservoir is at 1,442.5 feet AMSL.

Because Jamestown Reservoir is in the flood storage, the jurisdiction will switch from the Bureau of Reclamation to the Corps of Engineers.

The Corps of Engineers plans on releasing 30 cfs from Jamestown Reservoir by Thursday, March 30, according to an email from the Corps. Releases at Pipestem are currently at 17 cfs.

The releases from Jamestown Reservoir will help break up the ice and reduce the chance of ice jams, Martin said.

“If we have moving water, just the friction of the moving water plus the warmer water coming off the bottom of the lake will help soften and deteriorate the ice,” he said.

He said Reclamation doesn’t usually release water from Jamestown Reservoir during the winter because the water elevation hasn’t reached the flood storage mark. He said the water elevation is reduced to Jamestown Reservoir’s conservation level during the fall or early winter.

“Normally, it doesn’t come up during the wintertime because there isn’t runoff,” Martin said. “There must be a fair amount of groundwater that is coming into Jamestown Reservoir.”

Meanwhile, releases at Pipestem Reservoir have been at 17 cfs since January. Over the years, the elevation at Pipestem Reservoir has risen because water is added through groundwater springs, Martin said. Pipestem has routinely released a small amount of water starting in January, which also helps improve water quality and is good for fish, he said.

“We are drawing bad water off the bottom and then mixing it with the water that is discharged into the river, into the Pipestem Creek,” he said. “ … It replaces that bad water with better oxygenated water.”

Across the James River Basin, including Pipestem Creek, modeled risks for flooding north of Jamestown, Pingree and Grace City are below normal, according to the latest flood potential outlook released Thursday, March 23, by the National Weather Service in Bismarck. The outlook says the flood risk rises south of Interstate 94 due to areas having some of the highest snow-water equivalent in the state.

The outlook says dry and warm soils are still expected to substantially reduce the amount of runoff from melting snow in all but the most extreme melting conditions, including a rain-on-snow scenario. The region has seen below-normal temperatures with all weather forecast models suggesting that will continue into April.

“However, the closer we get to April and beyond, the greater the chance of seeing a rapid change in temperatures with daily highs potentially well above freezing,” the outlook says.If temperatures stay above normal for a while, Martin said that will speed up the amount of runoff from the snow melt.He said there is currently a lack of frost in the ground, which will allow a lot of moisture from the snow to be absorbed into the soil.

“When there is frost on the ground, 70% of the moisture usually runs off,” he said. “When there is no frost, there’s only 20%.”

He said there were a couple of inches of frost depth in areas by Gackle about a month agoa and one area at Pipestem Reservoir had about 6 inches of frost depth.

“When we were taking snow surveys up last week, you could tell there wasn’t a lot of frost just because we had to be careful that we didn’t get dirt in the bottom of the tube when we pushed the tube down to collect samples,” he said.

He said snow surveys were taken in areas where runoff flows into the Jamestown and Pipestem reservoirs. He said surveys were taken around Carrington, Grace City, Fessenden, New Rockford, Woodworth and just north of Jamestown and Pipestem reservoirs.

The water elevation has only reached the top of the spillway at Jamestown Reservoir once, during the flood in 2009. The top of the spillway is at 1,454 feet AMSL.

Last year, the water elevation went up around 1,442 feet AMSL.

“We handled that without any levies in town or sandbags or anything,” Martin said.