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Title: Mainstem Clearwater River Study: Assessment for Salmonid Spawning, Incubation, and Rearing.

Technical Report ·
DOI:https://doi.org/10.2172/5744691· OSTI ID:5744691

Chinook salmon reproduced naturally in the Clearwater River until damming of the lower mainstem in 1927 impeded upstream spawning migrations and decimated the populations. Removal of the Washington Water Power Dam in 1973 reopened upriver passage. This study was initiated to determine the feasibility of re-introducing chinook salmon into the lower mainstem Clearwater River based on the temperature and flow regimes, water quality, substrate, and invertebrate production since the completion of Dworshak Dam in 1972. Temperature data obtained from the United States Geological Survey gaging stations at Peck and Spalding, Idaho, were used to calculate average minimum and maximum water temperature on a daily, monthly and yearly basis. The coldest and warmest (absolute minimum and maximum) temperatures that have occurred in the past 15 years were also identified. Our analysis indicates that average lower mainstem Clearwater River water temperatures are suitable for all life stages of chinook salmon, and also for steelhead trout rearing. In some years absolute maximum water temperatures in late summer may postpone adult staging and spawning. Absolute minimum temperatures have been recorded that could decrease overwinter survival of summer chinook juveniles and fall chinook eggs depending on the quality of winter hiding cover and the prevalence of intra-gravel freezing in the lower mainstem Clearwater River.

Research Organization:
Nez Perce Tribe, Lapwai, ID (USA). Fisheries Resource Management
Sponsoring Organization:
United States. Bonneville Power Administration.
DOE Contract Number:
AI79-87BP37474
OSTI ID:
5744691
Report Number(s):
DOE/BP-37474-1; ON: DE89017702
Country of Publication:
United States
Language:
English