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Upper Klamath Basin Studies

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In 1992, the USGS began studying possible causes for the change in trophic status of Upper Klamath Lake. Since then research has expanded to include groundwater, geomorphology, streamflow forecasting, and fish ecology.

Upper Klamath Lake is a large, shallow lake in southern Oregon that feeds the Klamath River, which flows through California into the Pacific Ocean. The lake is naturally rich in nutrients (i.e., eutrophic), but has become hypereutrophic during the 20th century. Nutrient levels have been high enough to cause annual, extensive blue-green algae blooms each summer since the 1930's. Generally, a eutrophic lake can support diverse plant and animal communities. 

Water-quality problems that coincide with the blooms and subsequent decay of dead algae include foul odors, increased acidity, dissolved oxygen concentrations that fluctuate from supersaturation to depletion, elevated ammonia concentrations, and occasionally extensive fish kills. The degraded water quality is a contributing factor in the decline in populations of the shortnose sucker, Chasmistes brevirostris, and the Lost River sucker, Deltistes luxatus, both listed as Federally Endangered Species.

Research by USGS and others continues to monitor and assess conditions in Upper Klamath Lake and the surrounding watershed.