In 1988 the U.S. Fish and Wildlife Service listed two endemic fishes of the upper Klamath River basin of Oregon and California, the sucker and the Lost River sucker, as endangered under the federal Endangered Species Act (ESA). In 1997, the National Marine Fisheries Service added the Southern Oregon Northern coastal California (SONCC) coho salmon as a threatened species to the list. The leading factors attributed to the decline of these species were overfishing, blockage of migration, entrainment by water management structures, habitat degradation, nonnative species, and poor water quality. Endangered and Threatened Fishes of the Klamath River Basin addresses the scientific aspects related to the continued survival of coho salmon and shortnose and Lost River suckers in the Klamath River. The book further examines and identifies gaps in the knowledge and scientific information needed for recovery of the listed species and proves an assessment of scientific considerations relevant to strategies for promoting the recovery of those species.

During 2001, a severe drought occurred in the Klamath River Basin. The U.S. Department of the Interior (DOI) determined that the newly issued biological opinions and their RPAs must prevail; thus, water that would have gone to irrigators was directed almost entirely to attempts to maintain minimum lake levels and minimum flows as prescribed in the two RPAs. The severe economic consequences of this change in water management led DOI to request that the National Research Council (NRC) independently review the scientific and technical validity of the government's biological opinions and their RPAs. The NRC Committee on Endangered and Threatened Fishes in the Klamath River Basin was formed in response to this request. The committee was charged with filing an interim report after approximately less than 3 months of study and a final report after about 18 months of study. The interim report, which is summarized here, focuses on the biological assessments of the USBR (2001) and the USFWS and NMFS biological opinions of 2001 regarding the effects of Klamath Project operations on the three listed fish species.

The Klamath River basin, which spans parts of southern Oregon and northern California, has been the focus of a prominent conflict over competing uses for water. Management actions to protect threatened and endangered fish species in the basin have left less water available for irrigation in dry years and heightened tensions among farmers and other stakeholders including commercial fishermen, Native Americans, conservationists, hunters, anglers, and hydropower producers. This National Research Council book assesses two recent studies that evaluate various aspects of flows in the Klamath basin: (1) the Instream Flow Phase II study (IFS), conducted by Utah State University, and (2) the Natural Flow of the Upper Klamath Basin study (NFS), conducted by the U.S. Bureau of Reclamation (USBR). The book concludes that both studies offer important new information but do not provide enough information for detailed management of flows in the Klamath River, and it offers many suggestions for improving the studies. The report recommends that a comprehensive analysis of the many individual studies of the Klamath river basin be conducted so that a big picture perspective of the entire basin and research and management needs can emerge.