MaxDepth Aquatics, Inc.
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Odell Lake, Oregon
Odell Lake is a deep lake formed as a consequence of glacial activity in the Oregon Cascades. The lake is oriented east-west and its position at Willamette Pass funnels consistent winds through the pass and promotes large seiches in the lake. Odell Lake was classified as oligotrophic by state biologists in 1941. In July 2004, the lake experienced a major bloom of Anabaena flos-aquae with counts of over 330,000 cells/mL. MaxDepth Aquatics is under contract to help determine if the water quality in the lake has changed and if so, what are the causal factors. MaxDepth staff collected a sediment core from the lake (at 80 m) and analyzed the sediments for changes in sediment accumulation rate, abundance of cyanobacteria, diatom community composition, and nutrient chemistry. The results show that the lake has experienced substantial increases in sediment accumulation during the 20th century. The lake historically had relatively little Anabaena present prior to alteration of the fisheries. The major increases in cyanobacteria in the lake correspond with the period in which the kokanee became the dominant fish species. In addition MaxDepth staff completed an hydroacoustic analysis of the fisheries in Odell Lake to characterize the abundance and distribution of the dominant fish species (kokanee, lake trout) in an effort to protect the threatened native bull trout. The results reveal the presence of large schools of kokanee that disperse throughout the lake at nightfall to graze on the zooplankton (see echograms below).
The information on fish abundance is being combined with water quality data collected by the Oregon Department of Environmental Quality (link) and the paleolimnological data to determine if the current fish community has contributed to suspected changes in water quality and algal blooms. The hydrodynamic portion of the modeling (with CE-QUAL-W2) has been completed, reproducing the very large internal seiche measured by DEQ (for model animation click here).
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Copyright © 2003
MaxDepth Aquatics, Inc.
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