The Bureau of Reclamation (Reclamation) is the responsible Federal agency for operation of the Klamath Project (Project). Operation of the Project has been the subject of numerous previous consultations with the U.S. Fish and Wildlife Service (Service) and one with the National Marine Fisheries Service (NMFS) under Section 7 of the Endangered Species Act (ESA). Severe drought conditions in 1992 and 1994 and resultant associated shortages in project water supplies coupled with the 1997 listing of the southern Oregon/northern California (SONCC) coho salmon, Oncorhynchus kisutch, as threatened in the Klamath River downstream from the Project led to a review of Reclamation 19s operations. This biological assessment (BA) describes the effects on federally-listed species (i.e., coho salmon) and its designated critical habitat from on-going operation of the project based on historic operations, as described in this BA. The biological opinion (BO) addressing this BA and any subsequent BA amendments will be among the information that will inform the development of alternatives of the long-term operations plan and environmental impact statement (EIS). Reclamation is developing a long-term operations plan and EIS for the Project. The preferred alternative for implementation from the long-term operations plan would be the subject of a separate future ESA consultation. This BA describes the needs of anadromous fish with emphasis on SONCC coho salmon. It was developed using the best available scientific and commercial information on anadromous fish in the Klamath River. Coho salmon were listed as threatened on June 6, 1997 (NMFS 1997). The NMFS published a final rule designating critical habitat for SONCC coho salmon in May, 1999 (NMFS 1999a). Designated critical habitat for SONCC coho salmon encompasses accessible reaches of all rivers (including estuarine areas and tributaries) between the Mattole River in California and the Elk River in Oregon. Critical habitat includes all waterways, substrate, and adjacent riparian zones below longstanding, naturally impassable barriers. The areas upstream from Iron Gate Dam (IGD) (river mile 190) were not proposed critical habitat because areas downstream were considered sufficient for the conservation of the species. Reclamation has not evaluated whether the action that is the subject of this BA is consistent with its trust responsibility to Klamath Basin Indian Tribes. There are several important scientific reports and analyses (e.g., Phase II flow study) currently not available to Reclamation concerning threatened coho salmon, their habitat, and water quality as it relates to appropriate river flows that may be necessary to operate the Project consistent with the trust responsibility to Klamath Basin Indian Tribes. When this additional information becomes available, Reclamation intends to consider it during the development of the Project operations plans and include it in subsequent consultations with NMFS, as appropriate.