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Spring Chinook moving through Wanapum Dam’s modified fish ladders; trap/haul at Priest Rapids

Posted on Friday, May 02, 2014 (PST)

Modified fish ladders at central Washington’s damaged Wanapum Dam on the mid-Columbia River appear to be doing the trick for adult spring Chinook salmon headed upstream on their spawning journey.

As of April 23, 31 adult spring Chinook adult salmon and 270 steelhead have been counted exiting the reconfigured fish ladders at Wanapum, where a 65-foot-long crack in a spillway pier had forced the drawdown of the reservoir backed up behind the dam. Because of the drawdown – as much as 26 feet in elevation – pumps had to be added to feed the fish ladders with water, and temporary slides be constructed to allow the fish to safely exit the ladders into the reservoir above. The crack was discovered in late February.

Grant County Public Utility District, which owns the dam, continues to facilitate the trapping and hauling of fish at Priest Rapids Dam while the Wanapum ladder modifications are being evaluated under operating conditions.

As of April 27, 74 spring Chinook and 27 steelhead have been captured at Priest Rapids Dam, located downstream on the mid-Columbia, and transported for release upstream of Wanapum Dam.

The spring Chinook salmon surge up the Columbia-Snake river system continued this week with the peak count so far this year – 17,409 adult fish --recorded at Bonneville Dam’s fish ladders on Wednesday. That brought the 2014 count through April 30 to 78,662, which is well ahead of Bonneville’s 10-year average through that date, 45,734, and 2 ½ times last year’s total through April 30, 29,094.

The season’s high count last year was 7,301 on May 3. Chinook counted passing over Bonneville are categorized as spring Chinook through June 15; as summer chinook from June 16 through the end of July and then fall chinook from Aug. 1 until the end of the year.

The 2013 upriver spring Chinook return, as estimated entering the mouth of the Columbia River mouth totaled 123,100 adults, according to a joint staff report prepared by the Oregon and Washington departments of fish and wildlife. The 2014 forecast for upriver spring Chinook is 227,000 adults to the Columbia River mouth, which would be the 5th highest return since 1980 and 129 percent of the average return observed over the past decade (2004–2013).

The average date on which an estimated 50 percent of the year’s upriver spring Chinook salmon run will have passed Bonneville Dam is May 7, ranging from April 27 to May 12, according to Oregon and Washington officials.

Bonneville, about 146 river miles upstream from the Pacific, is the first dam the spring Chinook encounter on their trip toward tributary spawning grounds and hatcheries in Idaho, Oregon and Washington. Upper Columbia spring chinook and Snake River spring/summer Chinook, particularly their naturally produced components, are protected under the Endangered Species Act.

So far (through Wednesday) a total of 9,979 adult spring Chinook have been counted at McNary Dam in southeast Washington. It is the fourth hydro project the fish pass and the last before approaching the Columbia’s confluence with the Snake River.

A total of 5,571 spring chinook had been counted at the lower Snake’s Ice Harbor Dam through Wednesday while 378 had continued up the Columbia to Grant’s Priest Rapids Dam.

Juvenile salmon and steelhead passage is now under way at Wanapum and Priest Rapids dams, according to Grant PUD. Juvenile passage at Wanapum Dam will be accommodated through the dam’s fish bypass unit, spillways and advanced turbines, which all remain functional under the current reservoir elevation. At Priest Rapids Dam, the newly-installed Priest Rapids Fish Bypass is operational in time for the downstream migration.

Construction on the new Priest Rapids Fish Bypass began in 2011, and is built upon the success of the Wanapum Dam fish bypass approximately 19 miles upstream. The bypass design converts three existing spillways into fish slides at Priest Rapids Dam to provide downstream passage for migrating fish in addition to the spillways and turbines.

The three chutes are each more than 200 feet long and over 40 feet wide. Collectively, the fish bypass chutes are capable of passing 27,000 cubic feet per second of water and juvenile fish survival is anticipated to be 99 percent.

The bypass provides for a better use of water resources by reducing total water spilled for juvenile salmon from 110,000 cfs to 27,000 cfs. This efficiency allows for an increase in power generation while also improving fish passage. At a cost of $28 million, the project is anticipated to pay for itself in five to seven years with the increased potential for electric generation.

Beginning this week, Grant PUD will begin transporting and releasing approximately 3,400 tagged juvenile steelhead and yearling chinook salmon approximately 38 miles above Wanapum Dam via helicopter as studies on juvenile fish passage commence. These studies are a component of Grant PUD’s license requirements, specifically the NOAA Fisheries’ biological opinion and the Priest Rapids Salmon and Steelhead Settlement Agreement from 2008.

The studies will evaluate the survival and behavior of juveniles moving through the new Priest Rapids Dam Fish Bypass as well as fish passage throughout the Priest Rapids Project.

Results from the studies will inform Grant PUD and other agencies of potential impacts on juvenile salmon and steelhead during the low-river conditions. Results will also provide route-specific behavior and survival information through the Wanapum and Priest Rapids dam fish bypasses, spillways and turbines.

The Wanapum reservoir shoreline will remain closed during the current low-reservoir elevations to protect culturally-sensitive areas and for public safety. Grant PUD expects that the shoreline closure will remain in effect at least through the July 4th weekend.

All of the 11 irrigators with surface-water withdrawals on the Wanapum reservoir have successfully acquired permits to modify their irrigation systems. Under the current reservoir elevation, Wanapum Dam continues to generate electricity at about 50 to 60 percent of its capacity and is passing spring runoff flows in coordination with other dam operators on the river.

For additional information, visit:

Also see:

-- CBB, April 25, 2014, “Preliminary Estimates Of Potential Costs For Repairs At Wanupum Dam Pegged At $61 Million”

-- CBB, April 18, 2014, “Extended Fish Ladders, Trap/Haul: ESA-Listed Spring Chinook Moving Upstream Of Cracked Wanapum Dam”

-- CBB, April 11, 2014, “Wanapum Dam: Tribes Urge Feds To Be ‘Proactive’ In Requiring Monitoring, Evaluation Of Fish Passage”

-- CBB, April 4, 2014, “Fish Passage Fixes At Wanapum Dam To Be Completed April 15; Trap/Truck First Weeks Of Spring Run”

-- CBB, March 14, 2014, “Wanapum Dam Crack: With Spring Chinook On the Way Upstream Fish Passage High Priority”

-- CBB, March 7, 2014, “Crack In Wanapum Dam:Reservoir Drawn Down 26 Feet, Officials Assess Options, Fish Passage Strategies”

Columbia Basin Bulletin The Columbia Basin Bulletin e-mail newsletter is produced by Intermountain Communications of Bend, Oregon and supported with Bonneville Power Administration fish and wildlife funds through the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program. Articles republished by The Dalles Chronicle with permission.


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