News Release Archive

Klamath River Emergency Dilution Flows Not Required in 2017

Media Contact: Russell Grimes, 916-978-5100,

For Release: May 31, 2017

KLAMATH FALLS, Ore. – The Bureau of Reclamation announces that Klamath River emergency dilution flows will not be required in 2017 to mitigate the effects of a parasite called Ceratanova shasta (or C. shasta) on outmigrating juvenile salmon. The announcement is made following weeks of monitoring parasite spore concentrations and prevalence of C. shasta infection among outmigrating salmon, and monitoring conducted by Oregon State University, the Karuk Tribe and the U.S. Fish and Wildlife Service.

In February 2017, the 9th U.S. Circuit Court of Appeals ordered Reclamation to implement two types of flows to mitigate the effects of C. shasta on juvenile salmon; winter-spring flushing flows designed to dislodge and flush out an intermediate host for the parasite, and emergency dilution flows designed to reduce the concentrations of parasite spores in the water column. The winter-spring flows were conducted on multiple occasions during February and March 2017, after which Reclamation shifted its focus to planning for implementation of emergency dilution flows, which the court ordered to be implemented between April 1 and June 15 if certain disease thresholds were exceeded.

Specifically, the court ordered Reclamation to utilize up to 50 thousand acre feet to implement emergency dilution flows if:

  • C. Shasta spore concentrations exceed 5 spores/liter (non-specific genotype) based on quantitative polymerase chain reaction at any sampling station, or
  • Prevalence of infection of all captured juvenile Chinook salmon exceeds 20 percent for the preceding week at the Kinsman Rotary Screw Trap site.
These flows would be required until June 15 or until 80 percent of juvenile salmon had outmigrated if either of the preceding two thresholds were exceeded.

The court order also specified that the USFWS Arcata Office would develop the outmigration estimation model used to estimate the 80 percent cessation clause. The Arcata Office released the results of the predictive model May 15 which estimated that 80 percent of the wild Chinook had outmigrated by the week of May 7-13. To ensure a reasonable level of confidence that the wild salmon outmigration was complete, the court required an additional seven days be added to the estimate, making May 20 the last day emergency dilution flows could be required in 2017.

Reclamation appreciates the close coordination between a number of partners and stakeholders that allowed for expedited processing of fish and water samples, and the development of an emergency dilution flow implementation plan. Reclamation is encouraged by the near ideal outmigration conditions experienced by juvenile salmon during spring 2017 and it will operate the Klamath Project for the remainder of the water year consistent with the 2013 Biological Opinion. The court order and its flow requirements will remain in place until reconsultation of the 2013 Joint Biological Opinion is completed in early 2019.

For additional information, contact Laura Williams at (541) 880-2581 or

# # #

The Bureau of Reclamation is a federal agency under the U.S. Department of the Interior and is the nation's largest wholesale water supplier and second largest producer of hydroelectric power. Our facilities also provide substantial flood control, recreation opportunities, and environmental benefits. Visit our website at and follow us on Twitter @USBR; Facebook @bureau.of.reclamation; LinkedIn @Bureau of Reclamation; Instagram @bureau_of_reclamation; and YouTube @reclamation.