2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/24/2018 | 2:30 PM - 2:45 PM | MACROINVERTEBRATE COMMUNITY TRANSITION FOLLOWING CHANGES IN THE THERMAL REGIME BELOW A LARGE DAM IN OREGON | 420 A
MACROINVERTEBRATE COMMUNITY TRANSITION FOLLOWING CHANGES IN THE THERMAL REGIME BELOW A LARGE DAM IN OREGON
Large dams may be tens of meters or more in depth, resulting in strongly stratified reservoirs. Limited water withdrawal points can result in few temperature outflow options. At one such deep reservoir, on the McKenzie River in Oregon, outflows following dam construction resulted in downstream waters which were warmer than pre-dam conditions during the winter and colder during the summer. To minimize temperature related dam impacts a selective water withdrawal ‘temperature control tower,’ a 92 meter wet well with three intake slots and overlapping gates, was constructed and began operations during May 2005. Here we use 6 years of summer macroinvertebrate data, three years before the temperature control tower began operations and three years following (2002-2007), to assess the impacts of downstream temperature control on the instream benthic macroinvertebrate community. We also examine dam impacts by comparing reaches upstream of Cougar Reservoir to reaches downstream. Initial years show a dominance of Chironomids and warm-water tolerant species below Cougar Reservoir, compared to upstream sites. Following the operation of the temperature control tower, the downstream communities exhibited shifts to increasing cold-water and indicator taxa composition.
- Temperature
- Invertebrate
- Trait
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Presenters/Authors
Christina Murphy
(), Oregon State University, Department of Fisheries & Wildlife, christina.murphy@oregonstate.edu;
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Sherri Johnson
(), U.S. Forest Service, Pacific Northwest Research Station, sherrijohnson@fs.fed.us;
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William Gerth
(), Oregon State University, william.gerth@oregonstate.edu;
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Gregory Taylor
(), US Army Corps of Engineers, gregory.a.taylor@usace.army.mil ;
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