Spill and GBT Meeting with Oregon DEQ December 2006

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.

Separator Sampling

Fish Sampling

Caudal Fin Bubbles

Summary of signs of GBT ( )

Updated Risk Assessment Salmonids Other species

2006 Spill Implementation How did spill in 2006 compare to past years?

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

2001

2005 Spring

Dissolved Oxygen

Are we asking for additional spill??? No – based on preliminary analysis

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 –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.

Conclusions 1.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. 2.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. 3.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. 4. In season management of total dissolved gas can include a criteria for 120% anywhere.