Water levels: Reservoir above normal, river up a bit from usual

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Levels at the Pipestem Dam and Jamestown Reservoir are at or near the conservation pool level, according to Bob Martin, dam manager for the Army Corps of Engineers. The conservation pool is the planned level of the lake for the winter months.

“The Pipestem is about 6 inches higher than normal at freeze-up,” Martin said. “The Jamestown Dam is at a normal level at freeze-up.”

Levels reported Monday by the corps stood at 1,442.5 feet above mean sea level at Pipestem and 1,431 feet above msl for the Jamestown Dam.

Levels at Pipestem Dam were drawn to a foot below the conservation pool in October to facilitate maintenance work on the spillway structure. When that was completed the level was allowed to rise with the anticipation it would level off at about the conservation pool level.

“It came back about 18 inches by freeze-up so we’re 6 inches higher than any other winter,” Martin said.

The mild fall weather also contributed to the Pipestem freezing over on Nov. 22, about a week later than normal.

The corps is continuing releases from both dams with 30 cubic feet per second being released from Pipestem and 13 cfs from the Jamestown Dam. Martin anticipates those outflows will match the inflows to the lakes from springs and ground water infiltration through the winter.

“This is the highest it’s (Pipestem Dam) been at freeze,” Martin said. “It’s too early to tell if it will be a factor next spring — so much depends on the melt.”

The amount of groundwater in the river basin is another factor that may affect spring river levels.

“The last river readings we have at LaMoure were on Nov. 19 and at 140 cfs,” said Brian Twombley, hydraulic engineer for the corps. “Normal there for that time of year is 20 to 30 cfs.”

River level measurements are not taken after freeze-up due to the inconsistent readings caused by ice on the river. Twombley believes the higher-than-normal river flows this fall are caused by groundwater seeping into the James River and its tributaries.

“The whole landscape has a lot of groundwater that has to work its way through the system,” Twombley said. “What drives high water in the spring is snow melt or big rains but if the ground is saturated more water runs into the streams than soaks into the ground.”

But Martin said some factors are working toward a quieter spring melt season.

“The early snow helps insulate the ground,” he said. “If the frost isn’t as deep in the ground the snow melt soaks into the ground better in the spring rather than running off into the streams.”

Martin said officials will make the first measurements of the snowpack and calculations of potential runoff amounts starting in February.

Sun reporter Keith Norman can be reached at (701) 952-8452 or by e-mail at knorman@jamestownsun.com

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