Friday, June 24, 2016
Columbia Basin fish and water managers are planning for operations at Dworshak Dam on the Lower Snake River to regulate water temperatures for the benefit of migrating sockeye salmon this summer.
It was the dominant topic at Wednesday’s meeting of the Technical Management Team, an interagency panel that guides hydro operations throughout the basin.
And, it has been a topic on the minds of all Columbia River federal and state fisheries managers, as well as basin hydroelectric managers this year as they met in a forum in May. The forum was organized by the Northwest Power and Conservation Council to share data and set up what the Council is calling an “early warning system.”
The focus is on how warm water can harm sockeye spawners and the best way to keep temperatures below a 67 degree Fahrenheit threshold in waters between Dworshak and Lower Granite dams to aid that passage.
TMT and other managers want to stay ahead of the game by keeping Snake River temperatures as low as possible, rather than trying to re-cool water after it gets warm.
As it stands, the plan from TMT this week is to maintain temperatures at 67 degrees or lower using flow augmentation from Dworshak Dam beginning June 29.
The lower Snake River has had the fortune of maintaining relatively cool water temperatures recently, but a warming trend is expected to begin July 1. The 12-hour average temperature in the Lower Granite Dam tailwater yesterday was 61.26 degrees F. That’s expected to rise to about 64 degrees by June 27.
Flow augmentation from Dworshak Dam in order to maintain the 67 degree target or less gets underway once the river reaches 65 degrees.
There was some discussion at TMT about setting the target at 66 degrees or less, but it would involve starting flow augmentation earlier and that could use Dworshak’s valuable stored cold water earlier, leaving less water for later in the summer.
Oregon TMT representative Erick Van Dyke said there should be a greater emphasis on paying attention to water temperatures throughout the entire lower Snake River, rather than concentrating on temperatures in the reach between Dworshak Dam on the North Fork of the Clearwater River and Lower Granite Dam on the Snake River. Most Snake River sockeye in 2015 died before they reached Ice Harbor Dam, the lowest dam on the river.
There is growing evidence that summer sockeye are the most vulnerable to harm from warm water, compared with other salmon runs.
“Last year we saw some pretty clear indications that sockeye were affected by thermal blockages in the river,” one TMT member remarked. “Of all the fish we try to benefit in the river system, sockeye end up being in the worst condition in this section of river.”
In 2015, low flow conditions, coupled with extremely high air temperatures and warm water in the major tributaries in the lower Snake and Columbia rivers from mid-June to mid-July, resulted in the highest mainstem temperatures recorded in the Columbia River.
At 68 degrees F sockeye salmon begin to die and most of the fish passed Bonneville Dam in 2015 after the water temperature had hit 73 degrees F.
The Northwest Power and Conservation Council heard a “lessons learned” report at their meeting in April from Ritchie Graves, chief of the Columbia Hydropower Branch at NOAA Fisheries.
“There was a lot of in-season discussion about survival and getting fish past the Snake River projects,” Graves told the Council. “But, we probably talked too long. We needed to act more decisively.”
Graves and Idaho Department of Fish and Game’s Russ Keifer presented a draft of the report to the Northwest Power and Conservation Council that examined why few Snake River sockeye made it to Lower Granite Dam and even fewer found their way to spawning grounds.
For background, see CBB, April 15, 2016, “NW Power/Conservation Council Hears ‘Lessons Learned’ Report On High Mortality For 2015 Sockeye Run,” http://www.cbbulletin.com/436491.aspx
In fact, 99 percent of Snake River sockeye that were counted crossing Bonneville Dam died before they reached the upper Salmon River’s Sawtooth Valley where the salmon, listed as endangered under the federal Endangered Species Act, spawn. Just 56 adult sockeye salmon made it on their own to the Sawtooth Valley and another 51 were transported from a trap at Lower Granite Dam to the Eagle Hatchery in Idaho.
And only 3 percent to 4.5 percent of the fish heading up the Columbia River and into the Okanagan River ever made it to the spawning grounds. Some 10 percent to 15 percent made it to the Wenatchee River to spawn, the passage report said.
More recently, the Council has been heading up an effort to improve data-sharing and accelerate decision-making when hot weather heats water beyond what biologists believe is the upper thermal limit for salmonids, and sockeye are the most sensitive to higher temperatures.
The idea is, in essence, to create an early-warning system.
In May, more than 30 representatives of fish and dam management agencies talked by conference call about how to ready the region for another summer like 2015. The conference was inconclusive, but, according to Council information, topics emerged for future talks that include (http://www.nwcouncil.org/news/blog/sockeye-warm-water-update-june-2016/):
--Consider setting a water temperature trigger for emergency actions below the lethal limit of 68 degrees so that fish aren’t on the edge of catastrophe before options are discussed.
--Improve coordination and communication through existing committees that oversee river conditions and advise on fish-passage actions, such as the Fish Passage Advisory Committee and TMT.
--Document the locations of cool-water refuges where migrating adult salmon and steelhead can reside temporarily when water temperatures are high.
--Positon mobile laboratories along river corridors to be able to respond quickly to assess dead fish and determine causes of death and the effects of temperature.
--Close fisheries and reduce irrigation withdrawals in tributaries when conditions are lethal in order to protect fish and keep cool water in streams.
--Over the long haul, overlay climate-change models with the location of fish kills to improve the ability to forecast where and how often low flows and high temperatures might affect fish, then develop place-specific mitigation plans.
--Conduct additional temperature monitoring in rivers and in fish ladders.
One action that worked in 2015 was NOAA’s timely permitting process along with efficient actions by the Idaho Department of Fish and Game and the Nez Perce Tribes. The actions allowed Snake River fisheries managers to begin trap and haul operations at Lower Granite Dam when it appeared that sockeye had hit a thermal limit at the dam and would not enter the fish ladder.
Since then, the U.S. Army Corps of Engineers has installed a permanent adult fish ladder water cooling system that will pull cold water from deep in the Lower Granite forebay into the fish ladder.
(See Corps information on the project at http://www.nww.usace.army.mil/Missions/Fish-Programs/Lower-Granite-Fish-Ladder-Temperature-Improvement/ and CBB, June 17, 2016, “Corps Moves Forward On Fish Passage Improvements At Lower Granite Dam, Includes Fish Ladder Cooling,” http://www.cbbulletin.com/436933.aspx)
At the same time, adult migration will be monitored at both Lower Granite and Lower Monumental dams. Adult health will be monitored at the Lower Granite trap and if a passage emergency is declared, Snake River sockeye will be transported from the dam to Idaho.
The group will meet again, probably in December.