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PUBLICATIONS—Scientific Investigations Report 2005-5212

Scientific Investigations Report 2005-5212

Instream Flow Characterization of Upper Salmon River Basin Streams, Central Idaho, 2004

Prepared in cooperation with the Bureau of Reclamation

By Terry R. Maret, Jon E. Hortness, and Douglas S. Ott


Anadromous fish populations in the Columbia River Basin have plummeted in the last 100 years. This severe decline led to Federal listing of Chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss) stocks as endangered or threatened under the Endangered Species Act (ESA) in the 1990s. Historically, the upper Salmon River Basin (upstream of the confluence with the Pahsimeroi River) in Idaho provided migration corridors and significant habitat for these ESA-listed species, in addition to the ESA-listed bull trout (Salvelinus confluentus). Human development has modified the original streamflow conditions in many streams in the upper Salmon River Basin. Summer streamflow modifications resulting from irrigation practices, have directly affected quantity and quality of fish habitat and also have affected migration and (or) access to suitable spawning and rearing habitat for these fish.

As a result of these ESA listings and Action 149 of the Federal Columbia River Power System Biological Opinion of 2000, the Bureau of Reclamation was tasked to conduct streamflow characterization studies in the upper Salmon River Basin to clearly define habitat requirements for effective species management and habitat restoration. These studies include collection of habitat and streamflow information for the Physical Habitat Simulation System model, a widely applied method to determine relations between habitat and discharge requirements for various fish species and life stages. Model results can be used by resource managers to guide habitat restoration efforts by evaluating potential fish habitat and passage improvements by increasing streamflow.

In 2004, instream flow characterization studies were completed on Salmon River and Beaver, Pole, Champion, Iron, Thompson, and Squaw Creeks. Continuous streamflow data were recorded upstream of all diversions on Salmon River and Pole, Iron, Thompson, and Squaw Creeks. In addition, natural summer streamflows were estimated for each study site using regional regression equations.

This report describes Physical Habitat Simulation System modeling results for bull trout, Chinook salmon, and steelhead trout during summer streamflows. Habitat/discharge relations were summarized for adult and spawning life stages at each study site. Adult fish passage and discharge relations were evaluated at specific transects identified as a potential low-streamflow passage barrier at each study site.

Continuous summer water temperature data for selected study sites were summarized and compared with Idaho Water Quality Standards and various water temperature requirements of targeted fish species. Continuous summer water temperature data recorded in 2003 and streamflow relations were evaluated for Fourth of July Creek using the Stream Segment Temperature model that simulates mean and maximum daily water temperatures with changes in streamflow.

Results of these habitat studies can be used to prioritize and direct cost-effective actions to improve fish habitat for ESA-listed anadromous and native fish species in the basin. These actions may include acquiring water during critical low-flow periods by leasing or modifying irrigation delivery systems to minimize out-of-stream diversions.


Data Collection Methods
Analytical Methods for Instream Flow Characterization
Climatic and Hydrologic Conditions During 2004
Results of Study Site Investigations
References Cited
Appendixes A-G. Plan views, weighted useable areas, and passage criteria assessments for bull trout, Chinook salmon, and steelhead trout for study sites in the upper Salmon River Basin, Idaho, 2004

This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.

Download the report (PDF, 6.00 MB)

Companion files

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Send questions or comments about this report to the authors, T.R. Maret, (208) 387-1328, J.E. Hortness, (208) 387-1319, and D.S. Ott, (208) 387-1335.

For more information about USGS activities in Idaho, visit the USGS Idaho Water Science Center home page.

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