Irrigation project aborted by high river flow
WENATCHEE, Wash. — A project to ensure Columbia River water for about 3,000 acres of cherry orchards south of Wenatchee has been put on hold because of too much water.
A May 5 attempt to build a small coffer dam into the Columbia River to install two large pipes from the river into a pond used to irrigate the orchards was aborted because of high river flow.
The river was running at 45,000 cubic feet per second and 609 feet above sea level a month ago at Wenatchee. But now it’s running 165,000 cfs and close to its normal elevation of 613 feet because of spring runoff from mountain snow melt in Washington and Canada. Heavy flow through Wenatchee is likely to continue into mid-summer.
The good news is there’s plenty of water right now for the orchards, but the bad news is water could run short before the August cherry harvest on Stemilt Hill and Wenatchee Heights, said Kevin Juchmes, water manager of Stemilt Irrigation District.
Water will be cut off for a week to do the work whenever it is done, he said. Water is pumped from the pond uphill to orchards 2,500 higher in elevation.
He wants to get the project done before a U.S. Army Corps of Engineers permit expires Aug. 1 and doesn’t know if the permit can be extended for the work to be done after harvest.
A crack discovered in Wanapum Dam on Feb. 27, 58 miles downriver from Wenatchee, caused drawdowns of the river behind Wanapum and Rock Island dams. It left the pond system serving three irrigation districts out of water.
A Corps permit to install the pipes at 602 elevation was delayed until April 23 because of archaeological and fish screen concerns. Work was then delayed another week because of the contractor’s work schedule.
The contractor, Selland Construction of Wenatchee, began placing 4-by-4-by-4-foot sand bags into the river on May 5 to form a horseshoe-shaped coffer dam 75 feet into the river. The shore side was to be de-watered so excavators could dig trenches 11 feet deep for the placement of two, 36-inch-diameter, 80-foot-long steel pipes from the river into the pond.
The pond had been fed by gravity flow through a crushed rock berm between the river and the pond but sediments have clogged the bottom of the berm.
Sand bags were hoisted into the river by an excavator. A worker stood on bags that had been set to detach the next bags from the excavator. Workers were just three hours into the job before deciding it was too precarious, Juchmes said. The river level fluctuates and it had risen nearly a foot in that time, he said.
Sand bags sitting on the berm were removed and Juchmes said another attempt probably will not be made until July.