The Tullos lab at Oregon State University is investigating physical and biological responses of the removal of Chiloquin Dam on the Sprague River. Changes in sediment dynamics, channel morphology, invertebrate communities, and riparian habitat are being monitored.

Effectiveness Monitoring Data Library

Background and History

Chiloquin Dam was constructed in 1914 near the City of Chiloquin in south-central Oregon, approximately 30 miles north of Klamath Falls, Oregon. This 21’ high, 220’ long structure was positioned on the Sprague River, storing approximately 45,000 cubic yards of sediment (USBR 2005) a short distance upstream of the confluence with the Williamson River. Sediment models suggest this deposition of this material could extend the approximately 10 miles down to the mouth of the Williamson River at Upper Klamath Lake (USBR 2005). Three fish species that have historically occurred or currently occur near the Chiloquin Dam site, which blocked approximately 80 miles of habitat (BIA 2005), are currently listed as federal and/or state threatened and endangered (Reclamation 2003, FWS 2004, ODFW 2004), including the shortnose sucker (Chasmistes brevirostris), Lost River sucker (Deltistes luxatus), and bull trout (Salvelinus confluentus). Beginning in August 2008, the Chiloquin dam was removed during the lowest flow period of the year, leaving a steep riffle to progressively erode as winter flows rose.

Monitoring Strategies

Collaborative monitoring between the USBR, Klamath Tribes, USFW, USBR, University of Oregon, and Oregon State University of channel bathymetry, bed sediment distributions, suspended sediment concentrations, benthic macroinvertebrate communities, adult and smolt migration, and water quality will allow inferences biotic and abiotic responses to be drawn.

Resources and Pertinent Links

Chiloquin Dam Removal Monitoring Update, Vol I

Randle, TJ and JA Daraio. 2003. Sediment and Geomorphic Assessment for the Potential Removal of Chiloquin Dam. USBR Technical Service Center. Denver, Colorado.

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