After reading yesterday’s post on the recent Upper Deschutes fish salvage a reader contacted me and asked, “I’m hoping you can help me understand something. Why is the Middle Deschutes running so high when the Upper Deschutes is so low. Where is the water coming from?”. Every now and then I am reminded that not every reader of this blog has been deeply immersed in local water issues for years and years and I should periodically revisit some topics. Here was my response to his email.

Water is released for irrigation purposes from Wickiup Reservoir from mid April to mid October.  That water flows down to Bend where it is diverted into a series of canals.  So, during irrigation season the water in the river above Bend is abnormally high from a historical perspective and very low below Bend.  

Outside of irrigation season most water flowing into Wickiup is held for release the following year, so the river above Bend is low at that time.  But, water from the Little Deschutes, Spring River, Fall River, and some springs continue to flow into the Deschutes below Wickiup.   So, while the flow out of Wickiup is currently at 103 cfs, the gauge below Bend says the flow is currently at 434 cfs. 

The DBHCP (Deschutes Basin Habitat Conservation Plan) now requires that 100 cfs of water be released from Wickiup during non-irrigation season for the Oregon spotted frog.  Prior to the DBHCP the flow out of Wickiup during the winter could be as low as 20 cfs and all of that was from seepage through the earthen dam.  That 100 cfs, plus the water from the other inputs, is not diverted below Bend for irrigation which raises the Middle Deschutes during the winter.

Note that even at these higher flows, the Middle D is still well below historical levels.  434 cfs is better than typical summer flows but still way below the historical average of at least 1,500 cfs for this time of year.

Thanks for reaching out.  Perhaps I should put this on my blog.