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Rogue dam removal enters final stage
Irrigators face steep electricity bill for water pumps
Tam Moore For the Capital Press April 23, 2009
GRANTS PASS, Ore. - With a successful pump test last week, and a coffer dam blocking part of the Rogue River nearly to height, the multi-year project to replace an aging irrigation diversion dam with pumps enters its final phase this month.
The cooperative venture between Grants Pass Irrigation District, Oregon's Watershed Enhancement Board and the U.S. Bureau of Reclamation will result in pumped river water filling irrigation ditches sometime between May 7 and 15. With irrigation district manager Dan Shepard watching, Slayden Construction Group's electrical subcontractors fired up the pumps last week for the first of what will be several test periods.
"It's going very well," said Reclamation project manager Bob Hamilton by phone from his Boise office. "They are finding bugs, which you would expect in something like this, and they are fixing them."
He said Slayden, a general contractor from Salem, is a bit behind schedule on the complex installation of 12 electrical pumps, but ahead on construction of the coffer dam that will allow destruction of the northern section of Savage Rapids Dam. The project, including Reclamation engineering and environmental studies, is expected to cost $39.3 million. Congress appropriated the lion's share of direct construction costs.
Savage Rapids, a low head dam built by the irrigation district in 1921, diverts water for 9,000 irrigators around Grants Pass, and for small farms and vineyards upstream in the Evans Creek Valley of nearby Jackson County. Fish passage at the dam has prompted controversy and repeated engineering solutions for more than three decades. A federal lawsuit, driven by Endangered Species Act listing of Rogue River coho salmon as threatened with extinction, drove the settlement that resulted in going forward with dam replacement.
Initially, Reclamation planners looked at getting the pumps in place, and allowing one season of operation before tearing out the dam. When the project was modified leading to the first contract award in the summer of 2006, the timeline was shortened to get the dam removed by this December.
"This is all about coho. Coho are driving this," Shepard said last week as he stood next to the big pipeline above the Rogue that carried the first pumped water to a north-side ditch about 130 feet above river level.
It's the migration schedule of Rogue River salmon and steelhead that spell out when Slayden can and can't be in the water. This week's completion of the north side coffer dam is based on no more than 21 days of holding up late run winter steelhead awaiting passage to upstream spawning grounds.
As soon as the coffer dam is in place, two gates now handling downstream water passage at a velocity too swift for fish will be shut. Water will again flow into the aging fish ladder on the south side. That will open the way for upstream migration, and for later downstream passage of juvenile salmon that spent the winter upstream. During summer months the contractor will demolish the northern part of the dam protected by the big dike created from river rock and mud.
"We'll do it all over again" after the close of irrigation season, Shepard said.
Hamilton said a key fish feature for the new pumping station is a National Marine Fisheries Service standard that intake velocity can be no more than 4/10 of a cubic foot per second at any location on the fixed intake fish screen. During last week's pump tests, intake water movement was barely visible along the 123-foot structure that sits out in the river like a long boat dock. It's about 100 feet from the intake screen to the wet well where the 12 pumps suck water upward to the three irrigation district canals.
The total diversion is about 150 cfs. Under previous operations another 800 cfs was diverted to power pumps lifting water to the Tokay/Evans Canal. It went back into the river after spinning the machinery.
Going to electric pumps from the water-turbine power of the old dam will be spendy for district patrons. The meter started ticking on the district's tab when tests began April 14. Shepard estimates at current rates, this season's power bill will be between $220,000 and $230,000. Basic rates for district patrons average $81 an acre for 2009. It's figured at $161 for the first acre and $80 for each additional acre, which entitles an irrigator to 6 acre feet of water during the season. There are just under 8,500 acres served by the district.
In addition to the current power bill, patrons must pay off a pair of 15-year loans that replaced two of the hydraulic turbines that failed after the decision to replace the dam was made.
Freelance writer Tam Moore is based in Medford, Ore. E-mail: email@example.com.
Page Updated: Thursday May 07, 2009 09:14 AM Pacific
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