The Technical Management Team reviewed 2003 operations at Columbia and Snake River dams and declared the year largely to be a success.
Each year in November, TMT reviews in season operating decisions it made during the previous fiscal year, Oct. 1 through Sept. 30. This year it found significant successes in using water from Dworshak Dam to cool Snake River water into mid-September, two weeks beyond operations called for by the NOAA Fisheries 2000 biological opinion.
In addition, it was noted at the meeting that changes in the U.S. Army Corps of Engineers' flood control operations this spring resulted in additional water available from Dworshak reservoir that could be used when it was needed the most.
On the other side of the ledger, while survival of spring migrants exceeded BiOp targets, survival of summer migrating fall chinook and steelhead that were left in the river through lower Snake River dams did not, nor did upper and mid-Columbia River steelhead.
However, system survival did meet BiOp targets. System survival includes juveniles barged through the Snake and Columbia River systems and adjusts barged fish survival by an assumed delayed mortality value.
"We used the tools available to us and used good judgment this year," said Donna Silverberg, facilitator throughout the year for TMT. "We're getting better and smarter in making decisions."
In April, TMT asked for a change in flood control operations at Dworshak Dam in order to save more water in the reservoir so it could be used later to gain higher flows in the lower Snake River. That left the reservoir's elevation higher than normal on the critical end of March flood control date. The operation called for a shift that resulted in more stored water in the Dworshak reservoir while releasing more water from Grand Coulee Dam. An initial low water supply forecast of 67 to 69 percent of normal facilitated the change, although, with unexpected late rain and snow, the basin ended the year with an 87 percent of normal water supply.
The change in flood control allowed the Corps to hold 15 feet of storage to be used for lower Snake River flow augmentation, and it allowed TMT to extend high summer flows from Dworshak beyond the Aug. 31 planning date of the BiOp to Sept. 15 in order to aid with Dworshak's cool water late migrating juveniles and returning adult fall chinook.
"The April operation was great," said Chris Ross of NOAA Fisheries. "It put a lot of water on the fish."
However, shifting flood control operations isn't always something the Corps can do, said the Corps' Cindy Henriksen. "We're always willing to look at it, but the concern is that we'd then see a big rain event during the April period," she said. "If so, we probably would have had to release more water earlier. We have to watch closely when doing this."
"This was a hot year with low water," said Dave Statler of the Nez Perce Tribes. "Under these conditions it was a challenge to keep the lower river cool with the only tool available to us
Dworshak. We did as well as we could and used the water to the best advantage."
Other issues, conditions and statistics discussed by TMT include (not all are related to operations under the control of TMT):
- The U.S. Army Corps of Engineers was able to provide a pulse of water (950,000 acre feet) from Libby Dam for sturgeon operations on the Kootenai River despite a lower than average water supply in the area (78 percent of normal).
- The January 2003 water supply forecast at The Dalles, January through July, was 80.5 million acre feet, 75 percent of average and promised to be nearly as low as the water supply experienced during the 2001 drought year. But late winter and spring precipitation brought the water supply up to 87.7 maf, which is 82 percent of average. However, that period was followed by a dry summer that recorded the third lowest precipitation of the previous 60 years.
- Kyle Martin of the Columbia River Inter-Tribal Fish Commission said the year included a warm winter and a very dry summer. Summer precipitation numbers are: June was 50 percent of normal; July was 20 percent of normal; August was 56 percent of normal; and September was 83 percent of normal.
Martin predicts near normal precipitation and colder winter temperatures for 2004. The water supply, he predicted, would be near normal at 104 maf, or 97 percent of normal. Another forecast put the water supply at 110 maf, or 102 percent of normal. John Wellschlager of the Bonneville Power Administration warned that predictions this early in the season are subject to wide error bounds.
- The survival probability with the Removable Spillway Weir at Lower Granite Dam is 98 percent, plus or minus 2.3 percent, according to Henriksen, while survival with spill as the dam is 93 percent, plus or minus 6 percent. She said the Corps would like another year to evaluate the RSW after moving the Behavioral Guidance Structure at the dam to the north.
- The Corps transported 56 percent of spring chinook in 2003, 65 percent in 2002 and 99 percent during the 2001 drought year. It transported 76 percent of steelhead in 2003, 75 percent in 2002 and 99 percent in 2001.
- Libby reservoir was down 20 feet at the end of summer this year, despite a request by the state of Montana to draft the reservoir 10 feet less. With better water conditions and full Canadian reservoirs, the Bonneville Power Administration and the Corps are often able to come to an agreement with Canada for a swap of water that allows less drafting of the Libby reservoir during the summer.
- Although flows at Lower Granite Dam exceeded BiOp targets during the spring, they were lower at 30,000 cubic feet per second than the target in the summer, which is 50 kcfs.
- Flows at McNary Dam met the spring 220 kcfs target, but averaged only 135 kcfs in the summer, far below the 200 kcfs required by the BiOp.
- Ken Tiffan of the U.S. Geological Survey, presented information on behalf of Billy Conner of the U.S. Fish and Wildlife Service regarding the effects of summer flow augmentation this year on survival of subyearling chinook.
Among the nuggets of information he provided were:
- Cooler temperatures during rearing resulted in the lowest growth rate of the study years 1998-2003.
- A spike in flows at the end of May and early June resulted in the quickest passage of the juveniles in the years studied.
- The first cohort of tagged fish had the lowest survival, the first year of the study period that has happened. Generally the first cohort has had the highest survival rate. Tiffan said that could be due to the unusual amount of woody debris in the river at the same time.
- Without flow augmentation from Dworshak Dam during the summer, temperatures would have spiked to 25 degrees Centigrade in the lower Snake River. "Flow augmentation this year had a big effect in bringing temperatures down," he said. "Survival would have been 7-8 percent lower without the flow augmentation for three weeks after July 29."
Many of the presentations are available on the TMT web site. Click on meetings and Nov. 5 Annual Review agenda.
Related Sites:
Technical Management Team: www.nwd-wc.usace.army.mil/TMT/index.html
by CBB Staff
River Operators Assess 2003 Dam/Reservoir Operations for Fish
Columbia Basin Bulletin, November 7, 2003
See what you can learn
learn more on topics covered in the film
see the video
read the script
learn the songs
discussion forum
