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Ecology and salmon related articles

High Numbers of Chinook Spawners Hitting Hanford Reach

by CBB Staff
Columbia Basin Bulletin - October 11, 2002

Salmon born four years ago in the Vernita Bar area of the Columbia River's Hanford Reach are returning to their spawning gravels in near-record numbers.

Beginning Sunday, Oct. 13, fishery managers and hydropower system operators will control river flows to protect this critical spawning area.

Scott Bettin, Bonneville Power Administration fish biologist, said 78,000 fall chinook are expected to spawn this year in the reach between McNary and Priest Rapids dams. Such a return would nearly double last year's tally of 44,000 and become the second-highest return in 40 years of counting.

"A combination of actions taken by dam operators, along with favorable ocean conditions, is yielding excellent results," Bettin said, "We can also point to work done by the parties to the Vernita Bar agreement as a win for salmon."

Vernita Bar is a large gravel bar in the Columbia River four miles downstream from Priest Rapids Dam. There, and in three other places in the reach, salmon dig nests (redds) in the gravel to lay their eggs. When fish biologists find the first redds in early October the Vernita Bar flows are activated, adjusting water flow from Grand Coulee, Chief Joseph and five public utility district dams upstream of the reach.

The Vernita Bar agreement is unique in that the hydropower system normally requires more water during the day and less at night. The agreement reverses the process to help ensure higher survival of the Hanford Reach chinook.

From mid-October to the weekend before Thanksgiving, river levels below Priest Rapids Dam are reduced during the day. Lower water encourages salmon, which spawn during the day, to dig their redds lower on the riverbanks. At night flows are increased to allow more water to go downstream. The objective is to ensure that eggs are deposited in areas that will remain submerged until they hatch. Redds made higher on the river banks could dry out when water levels decrease. As the spawning season continues, fish biologists determine the amount of river flow needed over Vernita Bar to protect the redds. The winter protection level will be set on Nov. 24 and maintained until spring.

"The Hanford Reach is a great story and demonstrates that when fishery managers and power operators work together, success can be achieved," said Paul Wagner, fishery biologist with the National Oceanic and Atmospheric Administration. "Much of the success is built on scientific data and management measures that have been put in place to help achieve the potential of this resource."

Between April 15 and June 15, river levels are again managed, through the Hanford Stranding Agreement, to keep redds under water while salmon fry hatch and to help prevent the fry from becoming stranded on riverbanks.

BPA and the U.S. Bureau of Reclamation along with Grant, Douglas and Chelan county public utility districts, which operate dams in the mid-Columbia River, control the river flows. The National Oceanic and Atmospheric Administration, the states of Washington and Oregon, and the Yakama, Umatilla and Colville tribes are all involved in the Vernita Bar agreement. These agreements are among efforts to help restore salmon populations to the Columbia River Basin.

"After 16 years of managing this program, the returning adult salmon numbers speak well for the program and our progress toward salmon recovery," Bettin said. "The chinook are spawning in safe places, and the hydro system maintains some flexibility. The system works."

The Vernita Bar agreement was used three years ago as a template for operations to protect chum salmon redds below Bonneville Dam in November and December. "And, again," Bettin said, "we've had successful results, increasing the numbers of these fish that are protected under the Endangered Species Act."

Bulletin Staff
High Numbers of Chinook Spawners Hitting Hanford Reach
Columbia Basin Bulletin October 11, 2002

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