January 12, 2008 - Bend Bulletin, What Controls the Flow of Water in the Deschutes?
Jan 16, 2008
What controls the flow of water in the Deschutes?
Water managers ‘predict the future’ as they plan for summer irrigation
By Kate Ramsayer / The Bulletin
Janaury 12, 2008
At Bend’s Black Bear Diner on Wednesday, the talk was about the weather: how much snow had fallen, how deep the snowpack was compared with normal, what the rest of the winter might bring.
But it was more than just idle January chitchat: The men and women in the meeting room were some of the region’s water managers. And the answers to those questions help determine how much water will flow down the Deschutes River in the winter, and how much needs to be held back behind Wickiup Dam to ensure that irrigators will have enough water in the summer.
“Our goal is to maximize the amount that we can release to help the flow below Wickiup, but still meet those water rights for storage in the reservoirs and fill those by April 1,” said Kyle Gorman, region manager for the Water Resources Department. “What we essentially have to do is predict the future, which is very difficult.”
And with the weather changing from year to year, managers talk regularly to determine how much water is released below the dams.
“This year (the Deschutes is) low compared to last year, but it’s not anything out of the ordinary,” Gorman said.
Earlier this week, the water levels below the diversion dam north of Mirror Pond were almost half of the what they normally are. That was because one of the irrigation districts was diverting water for livestock. But by Friday, it was up to 450 cubic feet per second, which is just a little on the low side, Gorman said.
Water has been stored behind the dams on the Upper Deschutes since the mid-1900s, when the Bureau of Reclamation built the storage facilities so that land in Jefferson County could be irrigated during the summer.
People often wonder why the main flow of the Deschutes can be cut back to a minimum in the winter, said Bob Ringering, district manager for the North Unit Irrigation District. But that’s what was allowed in the original formula from the Bureau of Reclamation and the state water resources agency, he said.
“We were only obligated to have to release 20 cfs out of the reservoir,” Ringering said. “We try to work with different agencies whenever we can to try to release more unless it’s a real short water year.”
If Wickiup Reservoir doesn’t fill, which happens on average about four out of every 10 years, then the irrigation district will have to allocate water to farmers instead of simply letting them have what they need, Ringering said.
At the end of the irrigation season in October, the Water Resources Department takes stock of how much water is left in the Wickiup and Crane Prairie reservoirs to determine how much water can be released while still filling the reservoir, Gorman said. It figures out how much more water is needed to fill these reservoirs, uses models to forecast how much water will flow into the reservoir, and calculates how much water it should release below the dam into the Deschutes River, Gorman said.
This year, for example, at the start of the winter season the reservoir wasn’t as full as it had been last year, so the managers decided to be conservative with the amount of water released.
“We looked at the forecast, and we knew where the reservoirs were, and the forecast told us that unless you drop it down to the minimum, you won’t fill the reservoir,” Gorman said. “So we dropped it down to 20 to 25 cfs.”
The natural flow of the Deschutes below Wickiup is about 600 cfs, he said. More water flows into the river from the Little Deschutes River, Fall River, Spring River and natural springs farther downstream, adding the amounts that are released from Wickiup Reservoir.
Gorman and other staff at the Water Resources Department take a look at an updated forecast every month to see if more water should be released from Wickiup.
And in January, after some recent storms, the forecast calculations suggested that more than 100 cfs could be released.
At the meeting, Gorman passed around spreadsheets, colorful graphs showing the likelihood of the reservoir filling under different circumstances, the latest snowpack data and charts of how this year is stacking up to last year.
“I don’t think 50 to 100 cfs is unreasonable at this point,” Gorman told the group, later adding that he would suggest something closer to the 100 cfs point.
But that wasn’t the last word on the subject. The state agency consults with the federal Bureau of Reclamation and the North Unit Irrigation District to set the release levels, and those folks weren’t as convinced.
“After 40 years of operations on many, many watersheds, I’m more cautious,” said Leo Busch, manager of the Bureau of Reclamation’s Bend field office. “You don’t want to act too fast.”
The concern, Ringering said, is that while things are fine now, the weather could dry up for the rest of the winter and the reservoirs wouldn’t be replenished.
“Who knows what happens in the spring,” Ringering said. “We could not get any more (precipitation) and not fill it.”
So instead, Busch and Ringering were pushing for a release of 50 cfs now, possibly moving up to 75 cfs if things are looking promising, Ringering said. And the discussions on the subject continued through the end of the week.
It’s important to release water below the dam because low flows on the Deschutes can have an impact on the ecosystem, said Tod Heisler, executive director of the Deschutes River Conservancy, a Bend-based organization.
“We’re hoping that we can find some ways to obviate the need for them to crank it down,” he said. “It’s a disruption to the natural functioning of the river for fish and wildlife and vegetation.”
The organization has already negotiated a lease with the Lone Pine Irrigation District for some of the water normally stored in the winter; as a result an additional 10 cfs of water is being released. That brings the total released below the dam to about 35 cfs.
And the river conservancy is working to try to collaborate with other irrigation districts to bring the water levels on the Upper Deschutes to more natural levels in the wintertime.
“What we would really like to do is see if those same parties can’t come together and work on a long-term strategy,” Heisler said.
Kate Ramsayer can be reached at 617-7811 or firstname.lastname@example.org.