WENATCHEE, Wash. — Irrigators are scrambling to get water to thousands of acres of orchards threatened by Columbia River reservoir drawdowns.
The levels of two large river reservoirs were lowered — called drawdowns — after a major crack was discovered last month in Wanapum Dam. As a result of the drawdowns, irrigation intakes of numerous orchards were exposed, cutting off access to the water, and a system used by several irrigation districts serving thousands of acres of orchards on Wenatchee Heights and Stemilt Hill needs modification to obtain water.
Meanwhile, the main irrigation districts serving the Wenatchee Valley, Wenatchee and East Wenatchee have access to water.
CRO Orchard, a large operation south of Rock Island, “is moving rapidly” to extend its intakes and Spanish Castle Orchard is drilling a new well because its 60-foot well has no water, said Norm Gutzwiler, a Chelan County Public Utility District commissioner and Wenatchee cherry grower.
CRO is owned by Zirkle Fruit Co., Selah. Zirkle officials did not return phone calls for comment.
Jay Brunner, director of the Washington State University Tree Fruit Research and Extension Center in Wenatchee, said the center’s Sunrise Research orchard, near CRO, also is affected. He said he’s getting permits to extend the orchard’s river intake 200 feet but may not have water until early April. He said he’s looking at trucking in water needed now for delay dormant sprays needed to control spider mites and other overwintering pests.
Alyse Barnes, a cherry grower across the river from CRO, said officials visited the area March 21 and are expediting permits so she and neighboring growers can extend their intake pipes to reach water.
Orchards along the river — like Barnes, CRO, Spanish Castle and Sunrise — need water now for pest sprays and will need water within the next few weeks to irrigate trees and for frost protection. Wenatchee Heights and Stemilt Hill, some 2,000 feet higher, have more time since fruit trees there are slower to awaken from winter dormancy.
Chelan County PUD, which operates the Rock Island Dam, lowered its reservoir three to four feet after Grant PUD, which operates the Wanapum Dam, reduced its reservoir by 26 feet following the Feb. 27 discovery of a crack in a portion of that dam’s base. The lower water levels reduce pressure on the dams.
Grant County PUD has no estimate of how long its drawdown will last and says examinations of the crack will take at least until April 7. Reinforcement of the dam using cables and anchors is a possible solution, Chuck Allen, a Grant PUD spokesman, said.
The Rock Island reservoir was lowered to a little less than 608 feet above sea level on March 22 so irrigators could determine if they could access water through their intakes at that level. The normal level is 612 to 613 feet and the PUD hopes to maintain 609 with occasional dips to 608.
Those levels are too low to adequately supply a pond just off the river from which water is pumped uphill to Wenatchee Heights and Stemilt Hill. The Stemilt Irrigation District is trying to determine if the power supply is sufficient and if it can obtain permits to line the pond with plastic and pump water from the river into the pond.
“It’s pretty critical. Without it we won’t get any water,” said Kevin Juchmes, water manager of the Stemilt Irrigation District.
Normally, 10,000 gallons of water per minute is pumped from the pond to serve the Stemilt, Lower Stemilt and Wenatchee Heights irrigation districts and Kyle Mathison Orchards, Juchmes said. Wenatchee Heights sometimes gets by without water from the pond if nearby creek flow is sufficient and that probably will be the case this year, he said.
The pond system needs to be operational by May 1, he said.
Reduced river flow will also impact irrigators, and the river may be run at 30,000 cubic feet per second at times instead of 45,000 cfs, said Suzanne Hartman, Chelan County PUD spokeswoman.
The PUD estimates there are about 75 irrigators using the Rock Island reservoir and 10 reported after the March 22, 608-foot-level test, Hartman said. Of the 10, six intakes were out of the water, three were fine and one irrigation well was out of the water, she said.
Those irrigators whose intakes are out of the water will get permits where necessary to extend their pipes.
The Greater Wenatchee Irrigation District, which serves 4,500 acres of residences and orchards in and around East Wenatchee, began pumping water from the Rock Island reservoir on March 24. It normally uses 5 billion gallons of water annually and should be OK, said Mike Miller, secretary-manager.
It takes about a week to charge the system, including filling a 2 million-gallon reservoir uphill near Pangborn Memorial Airport from which the rest of the system is fed by gravity.
With 1,250- and 2,500-horsepower motors, the system can pump 72,000 cfs at full capacity. It draws water from four, 20-foot-long fish-screened intakes.
“Our main concern with water being so low is enough weight, enough head pressure above the intakes to help the turbines draw the water,” said Dale Whitmore, operator.
The system is pumping less water at the 608-foot level but was in danger of sucking air at the initial drawdown level of 604 feet, Miller said.
Wenatchee Reclamation District will begin filling its canals on April 7 but is not affected by the drawdown since it draws from the Wenatchee River at Dryden, upriver from the Columbia. The system serves 9,000 users, of which about two-thirds are agricultural, from Dryden down the Wenatchee Valley through the city and crossing the Pipeline Bridge to serve a portion of East Wenatchee.