This article was published on: 10/7/21 10:14 AM
Flow from Wickiup will fall from 600 cfs to 100 cfs as irrigation districts attempt to rebuild empty reservoir
As irrigation districts close the books on the 2021 irrigation season and turn off water supplies to patrons, other Deschutes River stakeholders are closely monitoring the impacts of the annual ramp down of the river level.
The curtailment of water at Wickiup Dam, expected to occur during the third week in October, means less water for amphibians and fish. In one part of the Deschutes, the drop strands fish in a 1-½mile channel where shallow pools sustain them until they can be rescued by volunteers with nets and buckets.
Further downstream, at the Bend Whitewater Park, diehard surfers will make the most out of a diminished standing wave that goes nearly flat when the winter water level drops. Meanwhile, kayakers and rafters pack up their gear for the season, as the river becomes too low for safe navigation.
These impacts occur annually in October thanks to the practice of storing water behind Wickiup Dam, to be used for summertime irrigation by farmers and ranchers in Jefferson County and other parts of Central Oregon. Before the dam, around 600 to 800 cubic feet of water per second flowed downstream to Bend in winter. Now it’s reduced to around 100 cfs.
Due to the numerous springs that feed the river, there was historically little fluctuation between summer and winter flows. The installation of dams results in swings that now go from 100 cfs in winter to 1,500 cfs in summer.
Kate Fitzpatrick, the executive director of the Deschutes River Conservancy, a nonprofit whose mission it is to restore water to the Deschutes River, said low flows in winter limit fish habitat and also create a disconnect with floodplain areas, impacting frog habitat and river function.
“The soils in the Deschutes are fine-grained alluvial, and then are exposed at low flows to freeze-thaw cycles, which contributes to erosion,” said Fitzpatrick. “When the river ramps up in the spring to twice its historic flow levels, these flows create massive erosion.”
The erosion stymies riparian vegetation growth, impacting macroinvertebrate populations, said Fitzpatrick. It has also widened the Deschutes channel by around 20%.
“Over 70 years this has resulted in the function and geomorphology of the river unraveling,” she said.
The stranding of fish, which occurs near Lava Island Falls, draws dozens of volunteers and fish biologists each year to help transfer them in buckets to the main channel. The situation is expected to continue for several years until irrigation districts are able to release more water into the river as conservation projects come online.
“The impacts to fish at Lava Island are an emblematic symptom of the widespread issues caused by the low winter flows and the highly-altered flow fluctuations between winter and summer,” said Fitzpatrick.
Josh Bailey, general manager for the North Unit Irrigation District, which operates the dam, said ramping down from 600 cfs to 100 cfs is a three-day process, done slowly to stay in compliance with the regulations set out by U.S. Fish and Wildlife Service. A rapid rise or fall of the river can damage breeding grounds for the Oregon spotted frog.
The goal of holding back water is to fill the reservoir to its capacity of 200,000 acre-feet, but drought combined with larger winter releases for the threatened spotted frog have prevented a complete refill in recent years. Last year the reservoir only reached a height of around 115,000 acre-feet, which is 58% of capacity.
Kyle Gorman, region manager for the Oregon Water Resources Department, anticipates that Wickiup will again reach around 115,00 acre-feet by April. With a very wet winter, the level could be 10,000 acre-feet higher, he said.
For farmers and ranchers, the ramp down occurs after Central Oregon’s worst irrigation season on record. The impact was especially hard on Jefferson County farmers, who have spent the past few growing seasons leaving large amounts of pasture unplanted due to the lack of water.
“The drought impacts have been significant to district operations and the patrons that we serve,” said Bruce Scanlon, district manager for the Ochoco Irrigation District. “A shortened season and a majorly reduced allocation have resulted in lower yields for producers.”
Closing their canals does not mean work stops for the irrigation districts. Central Oregon Irrigation District will spend this winter installing 7.9 miles of pipe between Redmond and Smith Rock to replace a portion of its canal, part of its $32 million canal-to-pipe water conservation project.
While it will be years before conservation projects have a real impact on the river, Fitzpatrick said the river will benefit in the long run. The Habitat Conservation Plan, which was signed by all eight irrigation districts in Central Oregon, commits them to increase the height of the river to 300 cfs by 2028.
The increase “represents truly historic progress getting this river system back in balance,” said Fitzpatrick. “More flows will be needed, alongside physical habitat restoration, to continue to restore the river.”
In addition to the Central Oregon Irrigation District project, North Unit will be undertaking a number of wintertime conservation projects, including the replacement of around 5,000 feet of open canal to high density polyethylene pipeline.
The Swalley Irrigation District is also planning water conservation projects to be implemented during the next two to three winters.
“This winter and next spring we’re focused on engineering future big piping projects and conducting proactive maintenance in preparation for what we expect will be another few rough summers ahead,” said Swalley’s General Manager Jer Camarata.
Getting an early start on storing water for next year is also a priority for the districts.
“We are cognizant of the fact that we want to start storing water sooner rather than later,” said Bailey. “So we are making this a short window of irrigation before we shut down.”