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Pahsimeroi River Subbasin

Pahsimeroi River Subbasin (Idaho) The Pahsimeroi River (HUC 17060202) is a tributary to the Salmon River, entering it at RM 304, and has a drainage area of about 825 square miles. In 2010, seven projects were completed in this subbasin that improved access for juvenile rearing and removed fish barriers for access to habitat upstream.

ESA-listed fish species present in the river include SR spring/summer Chinook salmon (threatened), SR steelhead trout (threatened), SR sockeye salmon (endangered), and Columbia River bull trout (threatened).

Pahsimeroi River Subbasin Juvenile Barrier: This project removed a check structure at Big Springs 3 diversion and replaced it with three rock-faced, sheet-pile A-weirs with improved fish passage. The new structures will provide improved juvenile access to Big Springs Creek from the BS-3 diversion upstream to the BS-4 diversion, approximately 4.2 miles.

Reclamation's Pacific Northwest Regional Office designed the structure. IDFG provided input into the type of design needed and wanted. IDFG coordinated with landowners and provided all environmental clearances and construction permits. Reclamation Salmon Field Office provided construction oversight

Pahsimeroi River Subbasin Juvenile Barrier - Before

(Before) Big Springs 3 Diversion Enhancement Project: The old check board diversion structure was a barrier to juvenile fish movement.

Pahsimeroi River Subbasin Juvenile Barrier

(After) Big Springs 3 Diversion Enhancement Project Photograph: The new diversion structure has three rock-faced, sheet pile A-weirs in series. Rock covers the sheet pile on both sides, and allows juvenile fish passage at all flows. Additional large rock placed in the center of the channel within the A-weir breaks up the velocity through the structures.

Last updated: 11/9/11