Migration Nearly Over,by CBB Staff
A sign that spring and summer fish passage operations is ending at federal Snake and Columbia River dams is the final decision to discontinue operating the Lower Granite Dam reservoir at its minimum operating pool level.
According to NOAA Fisheries 2000 biological opinion, the U.S. Army Corps of Engineers must operate the dam at MOP through the summer and early fall until the dam's pool cools after the several months of heating caused by summer sun. Operating at MOP ensures quicker passage through Snake River reservoirs and makes it easier to collect juvenile salmon for transportation on barges and trucks.
Having met that requirement at the dam, the Bonneville Power Administration asked the U.S. Army Corps of Engineers at this week's Technical Management Team meeting to raise the water level at the dam in order to increase the dam's ability to generate power.
"Since the BiOp has been met, we've checked off that box and want to operate the pool at its full range," said Scott Bettin of BPA. "The reason is for economics. The higher the reservoir elevation, the higher the head" and the greater the generation. He added that at the current low flows the additional four feet of head would add several megawatts per hour to the dam's energy output. At that rate, production increases would add up to about $60,000 over the next 21 days. That's until the end of October when MOP operations would automatically be discontinued.
NOAA Fisheries agreed that the criteria had been met -- the reservoir's water is now at about 65 degrees -- "so our issue has been satisfied," said the agency's Paul Wagner. "I don't feel strongly that we should maintain MOP."
However, other fisheries managers, represented by Dave Wills of the U.S. Fish and Wildlife Service, said they preferred to pass the remaining juvenile salmon still in the river before discontinuing MOP operations. Currently, the daily count of the sub-yearling chinook salmon passing through Lower Granite Dam is 400 to 500 fish.
"There are still a significant number of sub-yearling chinook in the river, mostly from the Clearwater River," Wills said. "The Nez Perce (not represented at this week's TMT meeting) want to move those down river. So, we'd like to maintain MOP to the end of transport."
Jim Litchfield, representing Montana at TMT, noted that the remaining fish are larger and stronger than earlier fish, so travel time through the pools is less of a factor on their survival.
Speaking for Greg Haller of the Nez Perce Tribes, Wagner said that, given a choice, the tribes prefer remaining at MOP because it may provide some incremental benefit for the remaining migrants. He also noted that the remaining fish represent 1 percent of the migration, although they account for a large contribution to total survival.
TMT decided to operate the Lower Granite pool at its full operating range, but to notify dam operators to operate within the pool's lower 1 foot when and if possible.
Technical Management Team: www.nwd-wc.usace.army.mil/TMT/index.html
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