With the salmon fly hatch on the Lower Deschutes River in full swing and many anglers pursuing trout that rise to the big bugs, I am getting frequent calls about the high flows. Anglers are somewhat used to flows higher than normal during wet years, but this year is exceptional.

To put the flows this year into perspective, during mid-May, the flow level by the Madras gage downstream of the Pelton Round Butte Project approached 7,000 cfs. The historical flow during mid-May averages less than 4,500 cfs. On some days these were the highest flows ever recorded, going back 86 years.

Several anglers have asked me if there is a way for the Pelton Round Butte Project to capture some of this high flow and discharge less. The answer is, we’re not allowed to reduce discharge flow significantly below incoming flow, except in special circumstances.

Federal hydro license comes with new restrictions
With the new federal license granted in 2005 to PGE and the Warm Springs Tribes, a number of new restrictions were added to prevent flow manipulation that might be detrimental to Lake Billy Chinook or the lower Deschutes River. One restriction requires Lake Billy Chinook to be within one foot of full from May 1 through Sept. 15. So during this period when recreation on the lake peaks, the reservoir is essentially full, and there is no room to store additional water. The only exception to the May 1 rule is during years when spring flows are very low, there are provisions to fill the reservoir very slowly by mid-May or mid-June. This delayed timing is to prevent reduction of downstream flows when the lower Deschutes is already below desired levels.

The other major restriction prevents us from discharging flows either significantly higher or lower than the flows entering Lake Billy Chinook. Unless there is an impending flood, outflows must be within 10 percent of inflows into the hydro project.

Upper Deschutes Basin Reservoirs
The four large Bureau of Reclamation reservoirs in the upper Deschutes Basin store some water for later discharge. Wickiup and Crane Prairie reservoirs store water for summer irrigation releases. Ochoco and Prineville reservoirs in the Crooked River Basin capture water for both flood control and later irrigation releases. However, these reservoirs are required to be full by a certain date. All four were nearly full during mid-May when heavy rain storms and snow melt created high flows, and thus what we saw was “natural” flow levels in a very wet year.

Here’s a handy web site I use to track the remaining storage in the Bureau of Reclamation Reservoirs and the water discharge volume: http://www.usbr.gov/pn/hydromet/destea.html

Fishing good, despite high flows
Even with the very high flows, friends and I have experienced quite good trout fishing on the lower Deschutes this spring. The trick is to fish very close to shore where big trout are awaiting the large salmon and golden stone flies that fall from vegetation. Fishing in locations less frequented by other anglers under trees or by the poison oak has seemed to increase my success.

- Don Ratliff, Senior Aquatic Biologist

This entry was posted on Friday, June 10th, 2011 at 12:48 pm and is filed under Deschutes River & tributaries, Fish, Portland General Electric. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.