Fisheries managers began trapping endangered Snake River
sockeye salmon from Lower Granite Dam Monday and transporting the fish to Eagle
Hatchery in Idaho as river managers struggled to keep the river cool. As of
Wednesday this week, just five fish had been captured and transported.
On Monday, managers trapped one sockeye and four on Tuesday,
as most of the returning Snake River sockeye, expected to be one of the largest
runs in recent history, are failing to show up at Lower Granite.
After exceeding the temperature threshold last week, the
U.S. Army Corps of Engineers has been struggling to keep water in the tailwater
at Lower Granite Dam below the 68 degree Fahrenheit threshold, which was set by
a NOAA Fisheries biological opinion in order to maintain cooler water
temperatures in the lower Snake River while adult chinook salmon and sockeye
Sockeye are listed as endangered under the U.S. Endangered
The temperature in the dam’s tailwater rose above 68 degrees
for the first time this year July 6 when it went to 68.04 degrees. It continued
to rise to 69.77 degrees July 8, but the Corps was able to drop the water
temperature to below the threshold by the weekend by increasing flows from
Dworshak Dam on the North Fork of the Clearwater River, a tributary of the
(See CBB, July 10, 2015, “Lower Granite Tailwater Temps Go
Above 68 Degrees; Returning Snake River Sockeye Stalling Through System,” http://www.cbbulletin.com/434488.aspx)
Water released from Dworshak Dam is about 42 degrees. The
dam provides a boost of cool water for projects in the lower Snake River and is
the only tool river managers have left to cool water in that section of the
The warm water is slowing the sockeye migration. While 810
sockeye passed Ice Harbor Dam on the Snake River, which is 145 percent of the
10-year average, only733 of the fish passed Lower Monumental Dam, 499 made it
past Little Goose Dam and just 34 have made it to Lower Granite Dam, the most
upstream of the four lower Snake River dams, said Paul Wagner of NOAA Fisheries
at this week’s regional Technical Management Team meeting.
“Clearly the fish are stressed and in rough condition,” he
said. The BiOp, he added, has an emergency provision that allows fisheries
managers to begin the transport program. Trapping of the fish is four hours
Idaho had requested the trap and hall operation for the
sockeye and NOAA Fisheries issued a letter of concurrence responding to that
request, Wagner said.
“This action had broad co-manager support and we determined
this action was consistent with provisions of the Section 10(a)(1)(A) permit
that NMFS had issued to Idaho Department of Fish and Game for operation of
their Snake River Sockeye Salmon Hatchery Program and the NMFS FCRPS BiOp,” he
“The emergency determination was made to allow operation of
the Lower Granite adult trap at temperatures that exceeded the Fish Passage
Plan's temperature criterion of 70 degrees F,” Wagner continued. “RPA action 9 of the FCRPS BiOp allows
operation of fish facilities outside of normal specifications due to unexpected
events. The extreme temperatures that
occurred at such an early date this season exceeded expectations.”
Pumps had been installed at Lower Granite Dam to draw water
from deep in the forebay to cool water at the adult trap. The pumps helped to lower temperatures, but
still, at times, exceeded 70 degrees.
Additional modifications are planned to provide even deeper, cooler
water that will be in place in for the 2016 migration season.
Lower in the Columbia River, the sockeye are stalling as
well and some are dying at Bonneville and The Dalles dams. Still, the sockeye
have done well this year, with 486,000 passing Bonneville Dam. Most of those
fish are headed up the Columbia River to the Okanagan River, Wagner said, but
they’ve stalled at Wells Dam because the Okanagan River is so hot.
The sockeye that are in the lower river are pulling in at
cool spots, such as Drano Lake on the Washington side of the Columbia River.
According to Steve Hall of the Corps’ Walla Walla District, the
temperature in the Lower Granite tailwater early Wednesday morning was 65
degrees, but he expected the temperature to go up later this week as air
temperatures are expected to again rise above 90 degrees Fahrenheit and sunny
skies will increase solar radiation.
He suggested to TMT managers to release more water from
Dworshak Dam beginning Wednesday evening, increasing flows from the dam’s 7,500
cubic feet per second up to full powerhouse flows, which are around 9.4 kcfs to
9.6 kcfs, in order to get the sockeye past the dam as soon as possible.
The water would reach Lower Granite Dam in 72 hours, just in
time, he thinks, to keep the water cool enough to maintain the temperature
buffer (66.5 degrees to 68 degrees) salmon managers desire.
In an attempt to also cool the pool just downstream of Lower
Granite to Little Goose Dam, the Corps turned off the removable spillway weir
at Lower Granite and is using power house number one, which is next to the fish
ladder at the dam. That, he said, will keep the colder water closest to where
the fish enter the ladder and it will put colder water down through the dam.
Hall explained that Dworshak water is very cold and
naturally stratifies. The water at five to ten meters, he said, is very cold.
Bringing water over the RSW brings water to the surface and it heats up in the
sun. As a result, the RSW has a detrimental effect on the water temperature
downstream, while putting water through the powerhouse cools the water
There is a price for using water now for the sockeye, but
its best to help with “struggling sockeye passage,” Hall said.
Computer models by the Corps show that if flows from
Dworshak remain at the current 7.5 kcfs through July, then a constant 7.5 kcfs
would be available in August (see the model run at http://www.nwd-wc.usace.army.mil/tmt/agendas/2015/0715_DWR_ops071515_SCH.pdf).
If flows rise to full powerhouse (about 9.6 kcfs) through
July, then just a little more than 6 kcfs would be available through August. At
50 percent maximum spill (about 11.6 kcfs), then about 5.3 kcfs would be
available through August. At gas cap spill of over 13 kcfs, about 4.3 kcfs
would be available through August.
For more information on Snake River sockeye see:
-- CBB, June 12, 2015, “NOAA Fisheries Releases Snake River
Sockeye Salmon Recovery Plan: 25 Years Of Actions At $101 Million” http://www.cbbulletin.com/434233.aspx
-- CBB, Jan. 16, 2015, “Snake River Sockeye Life-Cycle:
Returns Enhanced By Lipid-Rich Ocean During Smolts’ First Year” http://www.cbbulletin.com/432932.aspx