The First Chinook and Steelhead Smolt Migration in the Upper Deschutes Basin, Oregon in Fifty Years

Anadromous fish were extirpated from the upper Deschutes watershed in the 1960s.  Original dam construction included fish passage; however, it did not attract smolts.  To remedy this, and to manage downstream water temperatures, a selective water withdrawal and fish collection facility (SWW-FCF) was completed in December 2009.  We used PIT and radio tags to measure the growth, migration timing, travel times and routes of steelhead and Chinook smolts.  We calculated smolt production estimates and survival through the reservoir.  PIT-tagged Chinook grew an average of 0.58 mm/day, and steelhead grew 0.80 mm/day.  Steelhead had shorter travel times than Chinook, traveling an average of 2-3 km/day.   Between 25 and 50% of the PIT-tagged Chinook smolts, and 12-24% of PIT-tagged steelhead smolts were captured at SWW-FCF.  Of the radio-tagged steelhead that entered the reservoir, 65% were detected in the forebay, and 14% entered the SWW-FCF.  On average, the tributaries produced significantly more smolts than predicted by habitat models.  A total of 43,810 Chinook and 7,773 steelhead were captured by the SWW-FCF and released downstream.  Hydrological data show the reservoir in transition in 2010; despite this, we demonstrated the SWW-FCF can transport significant numbers of salmonids downstream.  Monitoring is on-going in 2011.