February 12, 2010 - Bend Bulletin Why The Low Flow In The Deschutes?
Feb 13, 2010
Why the low flow in the Deschutes?
Irrigation is partly to blame, but thin snowpack is a longer-term concern
By Kate Ramsayer / The Bulletin
Low flows in the Deschutes River have exposed mud in Mirror Pond and boulders across from McKay Park, but water officials say the river level should be back up by the weekend. Still, the relatively dry winter and thin snowpack could lead to a difficult summer for fish, farmers and others dependent on water flows.
This week, the Central Oregon Irrigation District is conducting a regular stock run to provide water for livestock, diverting about 220 cubic feet per second of water from the Deschutes River upstream of Bend, said Steve Johnson, manager with the irrigation district.
That's about 40 percent of the water that was flowing into Bend last weekend. Once the stock run ends on Friday, and the water is no longer diverted into a canal, the exposed rocks and mud should be underwater again.
“Over the weekend, people will see (the Deschutes) bounce back up,” Johnson said.
Mirror Pond is also shallow and muddy this week because of leaks in the dam at its base, said Kyle Gorman, region manager with the Oregon Water Resources Department.
“It leaks more water than is flowing in the river, that's why the pond level drops,” Gorman said.
In addition, the water level in the Deschutes River has generally been low this year due to a lack of precipitation and cold temperatures that prevent much runoff into the area's rivers, he said.
“This has been a dry year, and so the Little Deschutes, which plays a large role in the types of flows in Bend, has been extremely low this winter,” Gorman said. “We just have not seen any kind of runoff.”
Water managers are still hoping for a wet February and March, he said, but the current forecast for the summer calls for river flows in the basin that are between 55 and 75 percent of normal.
“We still have time, but statistically, it's getting harder and harder to make up that difference,” he said.
Because the Deschutes River is fed by reservoirs that the water managers can tap into through the summer, making up for the lack of natural flows, Bend residents shouldn't notice that much of a difference in the flow of the river through the city this summer, he said.
But for other waterways like Whychus Creek and Tumalo Creek, which don't have stored water available behind a dam, there could be low flows this summer, he said.
That's not good news for fish in those creeks, said Ryan Houston with the Upper Deschutes Watershed Council, since lower water flows mean poorer water quality and higher temperatures — colder water is best for the fish.
And irrigators that depend on creeks like Tumalo and Whychus could get less water this summer, Gorman said. With less water, they might only be able to get one cutting of hay instead of two, irrigate fewer acres or have to make other cutbacks.
Even irrigators drawing from the Deschutes River will coordinate schedules and timing to use as little water as possible from the reservoirs, Johnson said.
“You just want to manage a little bit tighter, as best you can, with the demand that your patrons have,” he said.
Wickiup Reservoir should fill this year, he said. But if a dry summer leads to irrigation districts drawing down the reservoir significantly, it will take a much snowier winter to fill it up again to get sufficient water for summer 2011.
“It has this ripple effect into next winter,” Johnson said.
Some sections of the Deschutes River could see a boost in water flows this summer compared with previous ones, he said. Because of projects to increase efficiency by replacing leaky open canals with pipes, Central Oregon Irrigation District and Swalley Irrigation District will have to divert less — and leave an additional 25 cfs or so in the river downstream of Bend, Johnson said.
And not everyone is worried about the relatively dry winter. Dennis Oliphant, the owner of Sun Country Raft Tours, said because of the release of water from the reservoirs, the Deschutes River always has good rafting opportunities.
“We're not concerned in the slightest,” Oliphant said. “We've been doing this for 32 years, and we've never had a year when we didn't have sufficient water to provide a good product.”
Still, dry conditions across the Northwest are causing problems for others.
The Bonneville Power Administration had to reduce its estimate for how much revenue it will produce at its hydropower facilities this year, according to a news release from the agency, since less water flowing down rivers in the Columbia basin means fewer turns of the turbines that generate electricity. The amount of runoff at The Dalles this year is expected to be the lowest level since 2001.
The BPA now expects to lose about $6 million, instead of making $232 million, as officials had predicted in October.
Kate Ramsayer can be reached at 541-617-7811 or at firstname.lastname@example.org.
Published Daily in Bend Oregon by Western Communications, Inc. © 2010