Don Ratliff, Senior Aquatic Biologist at Pelton Round Butte Hydroelectric Project gave an entertaining and highly informative presentation which covered three topics: 1) the performance of the newly operative temperature regulating tower in Lake Billy Chinook, 2) initial results for smolt migration in the salmon/steelhead reintroduction program, and 3) bull trout in the Metolius/ Lake Billy Chinook system.  Selected slides are posted below with Don’s permission.

The temperature-regulating tower operated pretty much as hoped for.  Some first year glitches were encountered, but overall the system moved warmer water out of reservoir earlier in the year.  This caused the lower Deschutes to be warmer early on, but cooler later in summer and fall compared to recent years.  As graphs show, this will be more or less the pattern for the future.  The reservoir will rapidly become a cooler body of water as a result of the system, so that in future years less warm water will have to be drained during the summer.  This will change the character of the reservoir itself dramatically.  It will biologically be more like a natural lake, with a much colder average temperature favoring the cold water species (kokanee/sockeye and bull trout) instead of a warm water species (smallmouth bass), in the future.

Smolt passage numbers and reservoir passage survival were of great interest.  Recovery of Chinook smolts at Round Butte Dam from the Crooked River system met the 50% safe passage goal, but steelhead smolt recovery was disappointing.  Optimistically we can hope that some of these steelhead smolts will migrate next year after an additional year in the upstream systems, as steelhead smolts vary in the number of years of residence in streams before migrating.  Next years results will be of great interest.  Don explained that the temperature structure of Lake Billy Chinook was still in transition during 2010, and better passage conditions are expected for 2011.

Bull trout were the main topic for the evening.  This is a complex topic, and significant differences of opinion exist on the subject.  We are fortunate to have the healthiest population of bull trout in the lower 48 states due to the very tributary streams in the Metolius Basin.  However this apex predator population, because of its abundance in this ecosystem, has the potential to impact the salmon/steelhead reintroduction program.  Extensive data was reviewed on the bull trout and kokanee populations.  The latter are the primary prey base for bull trout in Billy Chinook and are also being passed to create an anadromous sockeye run.  Management of bull trout under the ESA in these circumstances will pose some unique challenges.  We can expect further discussion and interesting follow up on this subject.

Attachments:

PGE Biologist Don Ratliff Bull Trout Presentation

[Slimmed down version of Don's Powerpoint Presentation]

2492 Kb

11/15/2010 18:42