While the upper Deschutes has been the focus of late, the middle Deschutes also needs additional flows. Unfortunately, there are no real plans for this. The middle Deschutes is generally defined as the segment from Benham Falls to Lake Billy Chinook and flows in this section are complex.
Flows in the middle from Benham Falls to the North Canal Dam in Bend, just upstream from the Mt. Washington bridge, mirror the upper Deschutes. During irrigation season (spring through the fall) the river is largely at a level that would have historically been associated with floods as water is released from upstream reservoirs. (The river no longer floods as the channel has been widened by these high irrigation flows over the past ~100 years.)
Large scale irrigation diversions begin just before the Bend city limits and end at the North Canal Dam. At that point the river is drained to a low and warm flow during irrigation season. The river does not become healthy fish habitat again until it is recharged by ground water springs around Crooked River Ranch.
I have read various estimates about the average historical flows in the upper Deschutes just below Wickiup Reservoir. I think that 500 cfs is a safe, if conservative, figure to use. At times in the recent past flows have been reduced to 20 cfs in the winter, a catastrophic reduction for fish and wildlife. The problem is nearly as bad in the middle below North Canal Dam.
As I write this the flow out of Wickiup into the upper Deschutes is 194 cfs (WICO gauge) while the flow just above Bend is 703 cfs (BENO gauge). That means 509 cfs is being added to the river between Wickiup and Bend from tributaries including the Fall River, Little Deschutes River, and Spring River. Add to that 500 cfs from the upper and it is not unrealistic to state that historical flows in the middle Deschutes through Bend were over 1,000 cfs year round. Last year, flows below North Canal Dam during irrigation season were as low as roughly 80 cfs. This is significant, comparable to the reductions in the upper Deschutes.
The proposed Habitat Conservation Plan does nothing to improve this situation. The irrigators commit to keep a “1-day average” flow of at least 250 cfs during the winter but not during irrigation season. It is already common for the middle Deschutes to be well above 250 cfs in the winter. More importantly, 250 cfs is of little value if the river is reduced to a small, warm stream in the summer. The aquatic environment during irrigation season will still be inhospitable at times regardless of what happened in the winter. Finally, as I have noted in other posts, the term “average” is concerning. A flow of 0 cfs one day and 500 cfs the next is an average of 250 cfs. What do they mean by “1-day average”?
It must be acknowledged that the middle Deschutes no longer has species listed under the Endangered Species Act. Bull trout have been extinct in the middle for a long time and anadromous fish never made it as far up the Deschutes as Bend. Accordingly, any improvements in flows are voluntary on the part of the irrigators. Nevertheless, I would have hoped that increases in flows in the upper Deschutes over time would have resulted in increased flows in the middle. The lack of commitment to increased flows is once again illustrative.