This article was published on: 11/29/10 12:00 AM
Tapping the Deschutes
Low water: Officials use river to fill reservoir
By Kate Ramsayer / The Bulletin
Published: November 24. 2010 4:00AM PST
Rocks and logs appeared in stretches of the Upper Deschutes River, and Mirror Pond started looking more like a mud flat, as water managers have dialed down the flow of the river for the winter.
Flows are at some of the lowest levels in years below Wickiup Dam because managers attempt to save up as much as possible in Wickiup Reservoir and Crane Prairie Reservoir in preparation for next summer’s irrigation season.
“The outflow out of Wickiup is cut back to the minimum. … We were not confident that we could fill both those reservoirs by releasing more than the minimum,” said Kyle Gorman, region manager for the South Central region of the Oregon Water Resources Department.
While there is no actual set minimum at Wickiup Reservoir, the releases don’t get lower than they have been recently. Earlier this week, the flow of water entering the Upper Deschutes from Wickiup Dam was 22 cubic feet per second — about one-eighth of the average flow for this time of year. The last time a similar amount was released from Wickiup was in 2006, Gorman said, when water managers released about 30 cubic feet per second.
This year, the water managers are storing as much water as possible behind the dam because of a number of factors, he said. Last winter was relatively dry, so there wasn’t as much natural flow in the Deschutes River this summer. Because of this, irrigators had to rely more on the water stored in Wickiup Reservoir this summer, Gorman said.
So the reservoir started out this fall with only about 40,000 acre feet of water in it — and the goal is to store 200,000 acre feet by April.
“Given the amount of water in the reservoir, and the projected inflow over the wintertime, if we didn’t set it at the minimum we weren’t sure that we could fill it,” he said.
The river was also even lower downstream of Bend over the weekend, he said, as Central Oregon Irrigation District diverted about half of the water flowing in the Upper Deschutes for a stock run to provide water for animals — something different irrigation districts do every month or two.
“That’s why the flows look low,” he said, noting that the stock run shut off Monday afternoon.
But the low releases from Wickiup, and some low water levels, will likely continue throughout the winter, Gorman said.
“We’ll monitor over the wintertime. If the inflow and the water supply situation improves dramatically, then we would make adjustments,” he said.
While the Deschutes River Conservancy has been working with irrigation districts to bump up the river flows in the Middle Deschutes downstream of Bend in the summertime, the winter flows in the Upper Deschutes are more challenging, said Tod Heisler, executive director of the Bend-based organization.
North Unit Irrigation District, which covers a lot of the larger agricultural operations in Central Oregon, depends on the water stored in Wickiup Reservoir, he said. And the district is already efficient with its water use, so it’s challenging to find ways to save water, Heisler said.
“It’s been harder for us to find some way we can benefit North Unit and the river at the same time,” he said.
When a river has very low flows, as well as a fluctuation between high flows and low flows, it can cause erosion problems, said Brett Hodgson, Deschutes district fish biologist with the Oregon Department of Fish and Wildlife. The change in water level, and the freezing and thawing that goes along with that, loosens up the ashy soil and causes erosion.
And it is hard on the fish, said Hodgson.
Many fish are territorial, he said, and when the water level drops, they have to find, adjust to and defend new territories.
“All that requires energy and is stressful on fish,” Hodgson said.
Kate Ramsayer can be reached at 541-617-7811 or email@example.com.
Published Daily in Bend Oregon by Western Communications, Inc. © 2010