Notes
Slide Show
Outline
1
Spill and GBT Meeting with Oregon DEQ
  • December 2006
2
GBT Impacts in Controlled Spill Program
  • Original criteria selected in 1995 based on best available knowledge.
  • Controlled Spill – managed to TDG of 120% tailrace and 115% forebay.
  • Data collected over full range TDG due to uncontrolled and over-generation spill.
  • Biological data suggests original assumptions were appropriate.
3
Separator Sampling
4
Fish Sampling
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Caudal Fin Bubbles
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7
Summary of signs
of GBT (1995-2005)
8
Updated Risk Assessment
  • Salmonids
  • Other species


9
2006 Spill Implementation
  • How did spill in 2006 compare to past years?
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Forebay Monitors
  • Recognized as problem in 2000 BIOP
  • Location of face of project presents issues for representative monitoring due to localized temperature and biological processes
  • Reviewed data three time periods without spill
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2001
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2005 Spring
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Dissolved Oxygen
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"Are we asking for additional..."
  • Are we asking for additional spill???


  • No – based on preliminary analysis
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Options for Future Monitoring
  • Establish criteria of 120% anywhere in river.
    • This will not increase spill levels over what was anticipated in 1995 or 2000 BIOP.
    • TDG downstream will dissipate as considered when establishing the criteria in 1995.
    • Easy to manage and most cost effective option.
    • Consistent with Biological data.
  • Consider managing for oxygen gas – remove oxygen from equation.  New monitors allow for better estimation.  Deleterious effects of oxygen not as much of a concern due to metabolism.



20
Conclusions
  • The amount of spill varies from project to project; with a few key projects having the greatest limitation on spill (Lower Monumental, The Dalles, Bonneville and Little Goose) based on the downstream forebay monitor readings.
  • The reason why the spill was significantly less at some projects is most significantly related to the management of spill to downstream forebay TDG levels.
  • The use of downstream forebay monitors for measuring dissolved gas relative to spill needs to be addressed.  Downstream forebay monitors, as presently configured, are not indicative of the readings in a well-mixed water column due to the local influence of temperature, barometric pressure and biological processes.
  •  In season management of total dissolved gas can include a criteria for 120% anywhere.