The reason for this is most of the Dams in the valley are having problems with the trunnion arms that lift the spill gates open. Most in the valley are old and need to be replaced. Detroit and Big cliff were the first two repaired so they are at normal flow, while almost all the other Willamette trib dams except Foster need to have MAYJOR repaires.
Because of this the Corp can't keep the reservoirs full for fear of the the trunnion arms breaking when they try to open the emergency spill ways, which would result in the water flowing over the top of the dam, and thats bad when its an earth fill dam.
For those of you that like to springer fish on the cement slab below Dexter Dam I got bad news for you, its been totaly washed out. Because of this trunnion arm thing they opened gate 7 at 14,000+ cfs this winter and it blew the slab away. Gone. Whats worse is the Corps current project manager doesn't plan on replacing it.