USGS Hydrologic Studies in the Upper Klamath Basin, Oregon

Ground Water

Long-Term Water Quality Monitoring

Nutrients

Upper Klamath Lake Sediment Oxygen Demand

Klamath River Sediment Oxygen Demand

Improving Streamflow Forecasts

Fish Response to Water Quality Variation

Sucker Ecology

Wood River Wetlands

Keno Reach Water Quality Monitoring and Modeling

Publications

Klamath Bibliographies

Data

U.S. Geological Survey

USGS Water Resources

USGS Water Resources of Oregon

Bureau of Reclamation

U.S. Fish and Wildlife Service

Oregon Department of Water Resources

Upper Klamath Lake is a large, shallow lake in southern Oregon. The lake is the source of the Klamath River, which flows through California into the Pacific Ocean. The lake has probably been naturally eutrophic since before settlement of the basin by non-Native Americans. A eutrophic lake contains a high level of nutrients, which can result in occasional algal blooms, but generally such lakes can support diverse plant and animal communities. During the 20th century, however, Upper Klamath Lake has become hypereutrophic, which means that its nutrient levels are high enough to cause annual, extensive blue-green algae blooms that have occurred each summer since the 1930's. (Excessive blue-green algae production is an indicator of hypereutrophic conditions.)

Water-quality problems that coincide with the blooms and subsequent decay of dead algae include foul odors, pH of 8.5 and higher, dissolved oxygen concentrations that fluctuate from supersaturation to depletion, elevated ammonia concentrations, and occasionally extensive fish kills. The degraded water quality has been proposed as 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.

The U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation, began studies in 1992 to determine possible causes for the change in trophic status of Upper Klamath Lake. Those studies have generated several publications, most of which can be accessed online.

In addition to studies funded in part by the Bureau of Reclamation, the USGS is cooperating with the Oregon Water Resources Department in a multiyear investigation of the ground-water resources of the Upper Klamath Basin, south into the Tule Lake-Clear Lake area.