Klamath River Geomorphic Assessment

Science Center Objects

The Klamath River is the third largest river flowing into the Pacific Ocean from the continental U.S. The headwaters of the Klamath are located in the Cascade Range in southeastern Oregon and the river flows through northern California to its estuary. Beginning in the 1860s, the flow and water quality of the Klamath started to change due to the building of dams and other water diversions for irrigation.

Klamath River Basin and four dams

Klamath River Basin and four hydroelectric dams

During the twentieth century, four hydro-electric dams were built, further impacting the ecosystem. Impacts include the altering of the channel bed and the blocking of 420 miles of upstream salmonid habitat, resulting in sharp declines in Klamath fish populations.

In addition to the hydro-electric dams, the U.S. Bureau of Reclamation (USBR) operates the Klamath Irrigation Project, providing water to irrigation districts in Oregon and Northern California. USBR operations were also believed to be impacting the fish population and in 2013, a Biological Opinion was published describing the effects of USBR Klamath Project on federally listed fish species. In the Biological Opinion, it was determined that a polychaete worm was the host for a parasite, Ceratomyxa shasta, known to causesignificant mortality in juvenile salmon. As a result, a "real-time fish disease management" system was proposed. This included the release of channel maintenance flows to disrupt polychate habitat decrease the presence of Ceratomyxa shasta and resultant fish disease.

In this project, scientists will study if the managed flows in the river are disturbing the polchaete habitat and reducing the spread of Ceratomyxa shasta. The primary objectives are to spatially assess river corridor conditions and the geomorphic effectiveness of streamflow in an area below Iron Gate Dam, and to relate the flow history to scour and bed mobility conditions necessary to manage fish disease. A secondary objective is to establish sites and methods for repeated monitoring and to develop baseline datasets for interpreting future river response to hydrologic disturbances including channel maintenance flows for fish disease mitigation.


Chinook salmon with a distended belly

The distended belly on this juvenile Chinook salmon is a clinical sign of Ceratomyxa shasta infection. Photo courtesy of USFWS. (Public domain.)

Science Plan 

River corridor conditions and the geomorphic effectiveness of flows below Iron Gate Dam will be assessed using field and remote sensing methods that include:

  1. Determining the grain size of mobile sediment on channel margins using pebble counts and bulk samples
  2. Mapping changes in vegetation to assess encroachment and scour of channel margins using repeat aerial photography
  3. Interpreting flow and turbidity time series records collected at USGS gaging stations located below Iron Gate Dam 

A fine-scale geomorphic and habitat map will be created to provide a foundational map for planning and implementing future monitoring and interpreting river responses to hydrologic disturbances.