This report describes objectives, methods and results for a macroinvertebrate study in the Deschutes River. This study is identified by the Pelton Round Butte Project License and was conducted consistent with a study plan developed in consultation with Portland General Electric and the Pelton Round Butte Fish Committee. A baseline study was conducted in 1999-2001, prior to the implementation of selective water withdrawal. This report summarizes results of two years of post-selective water withdrawal (SWW) sampling and a comparison with pre-SWW baseline sampling.
Post-SWW sampling was conducted in October in 2013 and 2014, and April/May 2014 and April 2015. Sample sites included nine mainstem sites downstream of the Project, with seven sites coinciding with sites sampled in both years during the baseline study; two additional downstream sites (at Sandy Beach and Macks Canyon) to provide additional information further downstream of Maupin; and three upstream above-Project reference sites on each of the tributaries feeding into Lake Billy Chinook (Metolius, Middle Deschutes, and Crooked rivers), useful for identifying any long-term changes in conditions potentially independent of SWW effects. Macroinvertebrate samples were taken using a D-frame kick net with 500-micron mesh, collecting four kick samples (each approximately 2 ft2 in area) at each site. At 8 sites, the samples were composited in accordance with ODEQ protocols; at the other 4 sites, samples were kept separate as replicates, to facilitate statistical comparisons. Periphyton samples were also collected at all sample sites, with only one composite sample (10 rocks, approximately 125 cm2 in area total) to be taken at each site.Keyword Tags: