Wickiup Reservoir water level to fall short again
Feb 09, 2020
North Unit's storage expected to reach just 75% of capacity
By Michael Kohn
From the top of the dam holding back the waters of Wickiup Reservoir, Curtis Wood, Josh Bailey and Gary Calhoun — three employees of the North Unit Irrigation District — huddled against the wind and peered down at the partially frozen water, a swirl of green and white.
Only half-full, the water level is not nearly where they would like it to be to provide a full supply of water to their patrons 90 miles away in Jefferson County.
“I feel disappointed (about the reservoir),” said Wood, the dam tender since 2012. “Disappointed yeah, but it’s also our weather pattern. We are in a drought season. It’s happened before. North Unit was in a drought when I first came here.”
Wood’s disappointment trickles down to North Unit farmers, who will again face a year of water shortages and tough decisions about how many fields to plant and how much to leave fallow. The better-than-average snowpack a year ago won’t help fill Wickiup as the impacts of drought from five years ago are still being felt at Wickiup .
“There is no chance to fill it up this year, no matter what we receive as far as snow for the rest of the winter,” said Kyle Gorman region manager for the Oregon Water Resources Department. “There will be a shortage, and it will be similar to last year.”
Wickiup was 57% full as of Thursday. Based on the current trend, Wickiup will end the winter season at around 150,000 acre-feet of water, about 25% below capacity, said Gorman. An acre-foot of water is the amount of water to cover one acre of land in one foot of water.
Built between 1938 and 1949, Wickiup Reservoir serves as a water storage unit for farmers on the North Unit Irrigation District, as well as a recreation spot for boaters, campers and fishermen.
The reservoir has completely filled just once since the record low snowpack in 2015. The struggle to fill the reservoir came to a head in 2018 when Wickiup went bone dry, exposing couches and other debris.
The Upper Deschutes area has “memory” says Gorman, meaning that better-than-average snowfall in just one year may not bring the reservoir up to normal.
Since the soil is porous, snowmelt seeps deeper into the ground and then reemerges as spring discharge, which takes longer to reach lakes and rivers. Most other reservoirs in Oregon will fill up more quickly due to clay in the soil that allows water to more quickly reach its destination. The upshot for Wickiup is that this year’s snowfall is less important than the snow that fell in previous years.
This year is expected to be the second-lowest fill in history next to last year’s record low, said Gorman. A year ago Wickiup topped out at 138,995 acre-feet and dropped to a low of 16,419 acre-feet on Sept. 18, 2019. The reservoir has a capacity to hold 200,000 acre-feet.
What is actually needed then, to fill the reservoir to the brim?
What’s crucial in building water supply at Wickiup is ending the irrigation season with the reservoir at 30%. Anything less than that will require a snowpack that is above normal, which is becoming increasingly rare. Snowpack last year was 110% of average but that’s not enough since the reservoir ended the irrigation season last year less than 10% full.
“One good year out of several bad years does not get you back to average, and that is what happens at Wickiup because there is such a strong groundwater component,” said Gorman. “The groundwater has depleted. We would need a big snow year like we had in the late ‘90s when we had about three years of super wet conditions. But we haven’t had it in consecutive years for a long time.”
Back at Wickiup, Bailey, the watermaster and construction supervisor for North Unit, descended down a spiral staircase 85 feet under the top of the dam to the bottom of a silo he called “the jug.” The name was given by the 1940s-era builders who thought the shape of the building was similar to the jugs in which they stored their booze.
Bailey passed emergency shut off valves in the jug and then down a 200-foot-long corridor housing the 8-foot diameter pipes that contain Deschutes water. The corridor led to a room containing the simple crank that Wood uses to open and close the main valves that release water into the river. It’s about the size of an automobile steering wheel and stamped with the year 1940.
Changes in water level are done gradually to protect Oregon spotted frog egg sacks, which are laid at the waterline, said Wood.
“If you go too much, they can get ripped up and float away,” said Wood. “We have to give a gradual ramp-up so nature takes its course.”
Outside the control room, water shoots out of the pipes at around 95 cubic feet per second into the river. Another 11 cubic feet of water comes out of a smaller pipe downstream, the source of which is water that leaked into the dam.
The sound of the water from the pipes is enough to drown out voices, but it’s just a fraction of the water that will come out of the dam in summer when more than 1,500 cubic feet per second will be released to the river. North Unit gets a portion of the water while the rest goes to other irrigation districts or continues all the way down the river to the Columbia River gorge.
Bailey worries that the snowfall hasn’t been enough in recent years to fill the reservoir to capacity, but he remains practical, pointing out the water conservation projects undertaken by the district and its patrons that have saved water for farmers.
The district was designed for 100% flood irrigation, Bailey said, but techniques that conserve more water — wheel lines, drip irrigation and pivots — have been installed on three-quarters of the district’s farm acres. This helps when Central Oregon’s snowpack just isn’t enough.
“You cannot control Mother Nature,” Bailey said. “You have to deal with the cards you’ve been dealt.”
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