Spring Spill Begins on Lower Snake Riverby CBB Staff
Columbia Basin Bulletin - April 2, 2004
Water will begin spilling over Lower Granite Dam on the lower Snake River tomorrow and the remaining three Snake River dams will follow suit in two-day increments during the next week.
The request was made this week by salmon managers at the Technical Management Team meeting for spill to begin April 3 and for the dams to go to minimum operating pools plus one foot in the same sequence.
Cindy Henriksen of the U.S. Army Corps of Engineers said spill of 12,000 cubic feet per second through the removable spillway weir at Lower Granite Dam will begin at 6 p.m. April 3. Spill at Little Goose Dam will begin April 5, at Lower Monumental Dam on April 7 and at Ice Harbor Dam on April 9.
However, TMT fish managers will check the status of migrating juveniles on Monday to determine if changes need to be made to spill start times.
Kyle Martin, Columbia River Inter-Tribal Fish Commission, said spill should have begun in mid-March and all projects should be operated at MOP, not MOP plus one foot. He said those requirements are included in CRITFC's River Operations Plan.
TMT is reserving a discussion about providing flow augmentation until its next meeting Thursday, April 8. It will also discuss at that time the beginning spring spill at lower Columbia River dams.
The availability of water for additional flow this year is getting more uncertain as water supply forecasts continue to sag. Henriksen said the March final water supply forecast by the River Forecast Center dropped to 87 percent of normal at both Lower Granite Dam and The Dalles Dam, and that those figures dropped further later in March to 85 percent at Lower Granite and 86 percent at The Dalles.
Spill begins this time each year as required by the NOAA Fisheries 2000 Biological Opinion of the federal power system dams in order to aid passage of spring juvenile salmon and steelhead migrants past those dams. At the same time, reservoir levels at the dams are set at MOP to increase the velocity of flow through the reservoirs. This year, as was also the case last year, TMT set reservoir levels at MOP plus one foot in the reservoirs to increase water depth for towboat operators who say that shoals forming due to a lack of dredging in the pools are causing hazards and they need more depth for safe passage. Only in Lower Monumental's reservoir, where the shoaling hazards don't exist, will MOP be maintained.
Technical Management Team: www.nwd-wc.usace.army.mil/TMT/index.html
Water Supply Forecast: www.nwrfc.noaa.gov/water_supply/ws_fcst.cgi
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