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Idaho Power Begins Fall Chinook Flow Regime; Lower Granite Counts Show Good Spawner Numbers
Posted on Friday, October 14, 2011 (PST)

Idaho Power began its annual Fall Chinook Program early this week by reducing outflow from Hells Canyon Dam on the Snake River to 14,000 cubic feet per second to provide steady flows for chinook salmon during their spawning season.

 

The reduced flow is scheduled to last until Dec. 5.

 

The program is part of Idaho Power’s commitment to protect and preserve the environment and also part of the requirements of the company’s federal license to operate hydroelectric facilities on the Snake River. The IPC owns the Hells Canyon Complex of three dams on the lower Snake.

 

Prior to this past weekend, the flow out of Hells Canyon was around 23 kcfs. During September and early October, Idaho Power lowered the level of Brownlee Reservoir, upstream from Hells Canyon Dam, to make room for inflows that exceed what is being released. Brownlee, the primary “storage” reservoir in the complex, was at 2,014 feet above sea level at the beginning of the Fall Chinook Program -- 63 feet below full.

 

It will begin refilling as inflows from the upper Snake River exceed the amount of water being released downstream. Average inflow to Brownlee Oct. 7-9 was 21.71 kcfs.

 

Release levels will be evaluated going forward to accommodate higher-than-average releases from federal Bureau of Reclamation dams on the upper Snake River, as well as wet fall weather.

 

Idaho Power began its Fall Chinook Program in 1990; the following year, 47 salmon redds, or nests, were counted in the Snake River below Hells Canyon Dam. In 2010, a total of 2,944 redds were identified – the highest number since counts began.

 

Better operations to help salmon populations migrate up and downriver have been a contributor to improving Snake River fall chinook numbers, as have beefed up hatchery programs, including one funded by IPC that involves releasing juvenile into the river just below Hells Canyon. There is not fish passage at the dams, which block access to historic spawning habitat upstream.

 

There should be plenty spawners this year. A total of 23,070 adult fall chinook salmon had been counted through Thursday passing over Lower Granite’s fish ladders on their way toward Hells Canyon Dam, Idaho’s Clearwater River and elsewhere. Lower Granite, a federally owned hydro project, is located about 140 river miles downstream from Hells Canyon Dam and is the eighth dam the fish clear during their spawning journey.

 

This year’s adult count already ranks as the second highest since counts began with completion of Lower Granite construction in 1975. The record total was 41,815 in 2010, which was more than double the previous high of 16,628 in 2008.

 

And there’s still quite a few spawners climbing over Lower Granite. Daily counts from Oct. 4-10 ranged from 134 to 282. Thursday’s count was 188.

 

This year’s fall chinook jack count at Lower Granite is also already the second highest on record. The total through Thursday was 17,647 which is second only to a total of 41,286 in 2009. Jacks are precocious males that return to freshwater after only one year in the Pacific Ocean.

 

The daily jack count at Lower Granite also remain relatively high, ranging from 234 to 590 Oct. 4-10. The count Thursday was 251.

 

Another good news run is that of coho. A total of 2,945 adult coho had passed Lower Granite through Thursday, making it the fourth largest on record already with more than 100 fish still passing the dam every day. The record total was 4,629.

 

Coho salmon had gone extinction in the lower Snake system. None were counted passing Lower Granite from 1987 through 1996.

 

The Nez Perce Tribe’s Clearwater Coho Restoration program, begun in 1994, is responsible for reviving coho populations, which now return to the Clearwater drainage to spawn. The Clearwater feeds into the Snake not far above the top of Lower Granite’s reservoir.

 

For updated Snake River flow and Brownlee elevation and boat ramp information, please visit http://www.idahopower.com/OurEnvironment/WaterInformation/default.cfm.

 

Additional information about Idaho Power’s Fall Chinook Program is available at http://www.idahopower.com/OurEnvironment/FishAquatic/Chinook/default.cfm

 

Information on reservoir levels on the Upper Snake River can be found at the U.S. Bureau of Reclamation’s website, http://www.usbr.gov/pn/hydromet/burtea.cfm

 

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