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Chinook Salmon, the Fish Screen, and a Vanishing River.

Chinook Salmon, the Fish Screen, and a Vanishing River. Paddy Murphy Idaho Department of Fish and Game Anadromous Screen Program Salmon, Idaho. Lemhi River. L-06 Diversion. L-06 Diversion – Obermeyer Weir. L-06 Diversion – Low water. 3,566 pre-smolts. 622 smolts.

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Chinook Salmon, the Fish Screen, and a Vanishing River.

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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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