Banks Lake Entrainment Study at Dry Falls Dam

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Banks Lake Entrainment Study at Dry Falls Dam
USBR

• Washington State Department of Fish and Wildlife
• Large Lakes Research Team
• Danny Didricksen

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Outline

• Relationship between Banks Lake and Lake
  Roosevelt
• 2004 - 2005 entrainment study situation and
  results
• Objectives for 2009 - 2011 study
• Site and situation
• Data collection
• Potential management implications

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Grand Coulee Dam
Feeder canal
Banks Lake
Lake Roosevelt
Image courtesy Google Earth
Banks Lake connectivity to Lake Roosevelt
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2004 - 2005 Study Site Location
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2004 - 2005 Entrainment Study

• Sampling was conducted about
• 5.6 km south of Dry Falls Dam
• from March - October both years
• East and West canals sampled
• with 1.5 x 1.5 x 5.5 m nets that had
• 2.5 cm stretch mesh
• Fish nets were utilized in 3-4 hour blocks for a
  given 18-24 hour period
• Zooplankton nets were deployed for single
  2-minute periods diurnally and nocturnally
  (variable sampling schedule, 2004 only)
• Water velocities and gauge heights were recorded
  in coincidence with all sampling events

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2004 YP COT Comprised 92 of all species
2005 YP COT comprised 91 of all species
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Entrained fish
Discharge flows
Fish captured
Discharge m3/sec
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Current Study
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DRAFT USBR
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WSBF Barge
10 x 10 x 46 trawl net will be lowered/raised
from the I-beam via overhead hoist
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Hydroacoustic array
Images courtesy HTI
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Comparison to 04 - 05

• There will be one net used, and it is much
  larger (10 x 10 x 46)
• Netting location will be just above the spillway
  instead of over 5.5 km below it
• - decreased lag effect between discharge and
  entrainment
• Zooplankton entrainment evaluation will be more
  structured
• Later initial start date
• Netting operations will experience more extreme
  dawdowns (particularly in Aug - Oct of 2011)

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What to expect from the study?

• Continued evaluation of the relationships
  surrounding discharge volumes and numbers of fish
  and zooplanktons being entrained at Dry Falls Dam
• Utilizing entrainment nets for species
  identification and hydroacoustic equipment
  for number/size/etc.-specific entrainment
  susceptibility
• Valuable information regarding reservoir
  operations and the impacts they have on fish that
  will impact future fisheries management decisions
• Initial impacts of the maintenance drawdown in
  2011
• Information to be used in bioenergetics and
  CE-QUAL W2 modeling, CH2M Hill for NEPA evaluation

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Thanks to