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Chinook Salmon Conservation: Lemhi River Case Study

Explore the conservation efforts for Chinook salmon in Idaho's Lemhi River, including fish screening, river flow management, and population monitoring. Learn about challenges, solutions, and progress made since 2000.

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Chinook Salmon Conservation: Lemhi River Case Study

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  1. Chinook Salmon, the Fish Screen, and a Vanishing River. Paddy Murphy Idaho Department of Fish and Game Anadromous Screen Program Salmon, Idaho

  2. Lemhi River

  3. L-06 Diversion

  4. L-06 Diversion – Obermeyer Weir

  5. L-06 Diversion – Low water

  6. 3,566 pre-smolts 622 smolts

  7. Lemhi Conservation Plan • Since 2000, Habitat Conservation Measures; At L-06 • 35 cfs will be maintained not less than 80% of the time from April 15 to June 30, • And 25 cfs will be maintained not more than 20% of the time from April 15 to June 30. One of the most contentious issues between NOAA and Irrigators.

  8. Spring Flow Crisis 2004-5 –Extraordinary Circumstances Litigation nightmare: • By Idaho Water Law, water master must deliver water by priority dates. • De-watering river = ESA take. • Everyone’s nervous: Irrigator’s, OSC, IDFG, NOAA fisheries, USFWS. • Third-party lawsuits.

  9. ISS Screw Trap • Capture and PIT tag out-migrating juvenile chinook salmon. • Estimate the population of juvenile salmon in the Lemhi River. • Calculate Travel Time to the Ocean. • Calculate Survival to the Ocean. • Calculate Survival Rates of Returning Adults.

  10. Entire mainstem screened. 78 fish screens. 35 fish screens above trap. 43 fish screens below trap.

  11. 5 fish screens below L-06

  12. L-03 Diversion

  13. L-03 Fish Screen Design flow 34.0 cfs

  14. Objectives • Document the relationship between smolt entrainment and flows in critical reaches of the Lemhi River. • Document the utilization of fish screen bypasses by Chinook salmon pre-smolts and smolts.

  15. Interrogated = 4%

  16. Interrogated = 27%

  17. Interrogated = 26%

  18. Interrogated = 9%

  19. L-03 PIT-tag Interrogations • In low run-off years, > than 25% of spring Chinook smolts were entrained at L-03. • 28% of interrogated smolts were interrogated at 2 PIT-tag readers, 5% at 3 readers. • In 2004, 50% (311) of all PIT-tagged smolts (622) were observed at LGD. • In 2004, 64% (118) of L-03 interrogated smolts were observed at LGD.

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