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Cooler Water Continues to Flow in Lower Snake River;
Fish Ladder Cooling Now Also at Little Goose

by Staff
Columbia Basin Bulletin, August 26, 2015

A Snake River sockeye swims in a tanker truck after it was trapped at Lower Granite Dam this summer. In an effort to help the sockeye stressed out from warming water temperatures and low river flows, crews trapped sockeye and transported them near Boise. Water in Lower Granite Dam's tailwater continues to run several degrees cooler than the 68 degrees Fahrenheit upper temperature limit set by NOAA Fisheries' 2014 biological opinion for Columbia/Snake salmon and steelhead, and the result has been improved passage for sockeye salmon.

Actions by the U.S. Army Corps of Engineers and the interagency Technical Management Team, which oversees river operations for salmon and steelhead listed under the federal Endangered Species Act, are ensuring that the conditions experienced last year are not repeated.

In 2015, endangered Snake River sockeye hit a thermal barrier at the dam and those that had made it that far failed to pass. A trap and haul operation transported some 50 of the sockeye from the dam's raceway to the Eagle Hatchery in Idaho. Some 101 Snake River sockeye made it to Idaho last year and just 44 swam all the way to Redfish Lake on their own.

As of early this morning, the 12-hour average tailwater temperature at the lower Snake River dam was just 65.8 degrees F, a temperature the Corps has generally maintained for a month.

(For daily tailwater temperatures at Lower Granite provided by the U.S. Army Corps of Engineers, see

In addition to cooler weather this year in the lower Snake River, the conditions have been kept cooler by cold water releases from Dworshak Dam on the North Fork of the Clearwater River.

Adjustable selector gates at Dworshak can access deeper, cooler water at various depths, which is released downstream in large quantities to cool the lower Snake River. At a temperature of 45 degrees F, Dworshak water cools the mainstem Clearwater River from 75 degrees to about 52 degrees. Three days after it is released from Dworshak that pulse or "wedge" of cold water reaches Lower Granite Dam.

The Corps also installed a permanent adult fish ladder water cooling system – Adult Fish Ladder Temperature Improvement System – that pulls cold water from deep in the Lower Granite forebay into the fish ladder.

The system is working well, according to a Corps press release. The Corps is seeing fewer adult salmon fall back downstream as they did in the past when encountering thermal barriers in the fish ladder.

A similar device at Little Goose Dam is also operating. It pumps water from a 60 foot depth in the Little Goose reservoir, where there is 63 degree water, into the dam's fish ladder. Surface water highs at the dam are in the 70s, according to the Corps.

"We're applying lessons learned upstream at Lower Granite," said Roger Golladay, the Corps' operations project manager at Little Goose. "We're using a system here this year similar to what Lower Granite used in 2014 and 2015 to cool their adult fish ladder."

The Corps also modified Lower Granite powerhouse and spillway operations to enhance attraction of adult fish to the ladder, the Corps said. Powerhouse operational changes included changing which turbine units were operated. Spillway operational changes included closure of the spillway weir at the request of TMT. These adjustments created a cooler water flow profile downstream of Lower Granite to best attract adult salmonids to the fish ladder entrance.

See Corps information about the Lower Granite Adult Fish Ladder Temperature Improvement System, plus downloadable photos, at the Walla Walla District website

Also see: CBB, June 17, 2016, Corps Moves Forward On Fish Passage Improvements At Lower Granite Dam, Includes Fish Ladder Cooling

Of the 342,479 sockeye salmon that have passed Bonneville Dam in 2016 (as of Thursday), about 1,240 were destined for the Stanley Basin. The total run of sockeye, which includes fish that head up into the Okanagan River in northern Washington, is far fewer than last year when 510,552 passed Bonneville by the same day, but more than the 10-year average of 285,055. Few sockeye are still passing Bonneville, with just one passing Wednesday and two passing Thursday.

As of Thursday, some 811 sockeye had passed Lower Granite Dam, while just 413 had passed at this time last year. The 10-year average is 982.

As the month turns to September next week, the Corps is planning changes to water output at Dworshak Dam, according to Doug Baus, fisheries biologist with the Corps.

"As coordinated in our previous TMT meeting the Corps will draft to 1535 feet by August 31," Baus said in an email. To do that the Corps may need to reduce discharges from the current outflow of 7,000 cubic feet per second down to about 6 kcfs based on current inflow forecasts as soon as Sunday, August 28.

September 1, Unit 3 (220 megawatts) at Dworshak will be removed from service for an overhaul, limiting the powerhouse capacity to about 45 percent of normal, Baus said. Water flowing through two smaller units, plus 110 percent total dissolved gas spill, will maintain flow at 6 kcfs. "All units will operate in undershot mode to achieve water temperature near 45 degrees F," Baus said.

Discharge at Dworshak will go to 4.6 kcfs September 14, and will stay there for at least two days, with discharge water to remain between 44 and 46 degrees F.

Discharge goes to 2.4 kcfs about September 17, for at least two days or until the Dworshak pool is at a 1,520 foot elevation.

Outflow will go to about 1.5 kcfs when the reservoir pool drafts to elevation 1520 feet (forecasted to be about September 20).

Current Dworshak Dam project data is at:

Related Pages:
First Snake River Sockeye Reaches Sawtooth Basin by Staff, Columbia Basin Bulletin, 7/31/15
Corps Report on 2015 Columbia/Snake Warm Water, Fish Die-Off Will Discuss Actions to Avoid Repeat by Staff, Columbia Basin Bulletin, 4/1/16
Post-Mortem 2015 Snake River Sockeye Run; 90 Percent of Fish Dead Before Reaching Ice Harbor Dam by Staff, Columbia Basin Bulletin, 12/4/15
Report Analyzes Impacts, Causes of This Year's Warm Fish-Killing Water in Columbia/Snake by Staff, Columbia Basin Bulletin, 11/6/15
Snake River Sockeye: Lowest Return Since 2007, Captive Broodstock Program Increases Spawners by Staff, Columbia Basin Bulletin, 9/11/15
Smoke, Lower Air Temperatures Keep Lower Snake Cooler by Staff, Columbia Basin Bulletin, 8/28/15
Last Of Dworshak Water for August? 400 Snake River Sockeye Between Lower Granite, Sawtooth Basin by Staff, Columbia Basin Bulletin, 8/14/15
NOAA's Snake River Sockeye Salmon Recovery Plan:25 Years of Actions at $101 Million by Staff, Columbia Basin Bulletin, 6/12/15

Related Sites:
With Cooler Weather, Snake River Sockeye Showing Decent Numbers Reaching Lower Granite, Sawtooths by Staff, Columbia Basin Bulletin 8/12/16
Compared To Last Year, Cooler Temperatures Seem To Be Giving Snake River Sockeye A Break by Staff, Columbia Basin Bulletin 7/5/16
Steps Taken To Cool Warming Lower Snake, Reduce Thermal Blocks During Large Basin Sockeye Return by Staff, Columbia Basin Bulletin 7/1/16
Columbia Basin Salmon/Hydro Managers Gear Up For Another Hot Summer: Will Sockeye Get Slammed Again? by Staff, Columbia Basin Bulletin 6/24/16
Recent High Sockeye Returns To Columbia River Expected To Decline In Next Few Years by Staff, Columbia Basin Bulletin, September 4, 2015

Cooler Water Continues to Flow in Lower Snake River; Fish Ladder Cooling Now Also at Little Goose
Columbia Basin Bulletin, August 26, 2015

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