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July 27 — Despite the release of 1.5 million acre-feet of water from headwater reservoirs in Canada, sockeye salmon carcasses riddled with fungus or bacteria litter some reaches of the Columbia River system, a result mainly of water that is too warm.
“Every little bit helps,” Ritchie Graves, Columbia hydropower branch chief for the National Oceanic and Atmospheric Administration, said of the release of water from Canada.
Even with the additional Canadian water—and millions of additional acre-feet drawn from federal projects around the basin, which is the size of France—Graves said that somewhere between about 50 percent to 80 percent of the fish died in the lower Columbia this year.
“We are doing our best with extreme circumstances,” he told Bloomberg BNA July 24.
Sockeye salmon and several other species are listed as threatened or endangered under the Endangered Species Act.
Federal water managers are faced with low flows caused by historically low mountain snowpacks.
“On top of the low flows, we had probably the worst heat wave we've ever seen in May in the Northwest,” Graves said. “The consequence of that is most of the river systems in the Northwest, including the main-stem Columbia, were running five or six degrees warmer than they normally do in June. Even once they cleared the hydro-system, they still have to migrate through extremely warm tributaries, which are as hot or hotter than the main-stem.”
Sockeye returning from the sea to spawn upstream numbered about 500,000 fish for all runs in the basin, which Graves said was excellent. So the arduous river conditions makes for what he said “is really a disappointing year.”
He anticipated that more than 80 percent of the fish will die before getting to their home pools.
Dams dot the length of the once free-flowing river and their pools soak up heat from the high-desert sun. Federal water managers such as the U.S. Army Corps of Engineers' Steve Barton, chief of the Columbia Basin Water Management Division, are tapping water from behind dams throughout the system to augment flow and cool down the rivers.
The system is in a dry-year strategy, Barton told Bloomberg BNA July 24. That strategy is based on the 2014 Federal Columbia River Power System Biological Opinion issued by NOAA Fisheries. It provides for the release of water under certain conditions such as when river temperatures are too hot for the 13 salmon and steelhead listed species in the basin.
“We've been hanging by our fingernails in terms of keeping the temperature at or below 68 degrees at Lower Granite Dam,” Barton said. “And some of the tributaries are quite warm in the Snake River basin. There are a few in the 70s even as of today,” he said July 24 when temperatures had finally moderated after weeks of unremitting heat.
Flows on the lower reaches of the Columbia river are expected to be roughly 71 percent of normal through August, he said. But managers anticipate that will be adequate to provide for both hydropower turbines and migrating salmon. It isn't so much the low flow, as the hot water temperatures that kills the fish.
Under terms of the Columbia River Treaty with Canada, the U.S. invoked dry-year triggers under the treaty and a side agreement to draft 1.5 million acre-feet from projects such as Mica Dam, one of four dams in the far northern headwaters of the river in British Columbia. Seasonal precipitation there was near normal, Barton said.
Combined with drafts contemplated by the treaty to ensure water for downstream hydropower, Canada contributed more than half of the estimated 8 million acre-feet of flow augmentation.
The hydropower augmentation “this year happens to have other benefits,” Barton said. “It's coming at a time that is putting water on the backs of those fish.”
On the U.S. side of the border, Libby and Hungry Horse dams in Western Montana are being drawn down an additional 10 feet, Barton said. Grand Coulee Dam in north central Washington is being drafted two feet. Cold water from the Dworshak Dam, which is more than 700 feet tall on the north fork of Idaho's Clearwater River, is being used to provide flow augmentation and temperature control downstream to the lower Snake River.
Barton said the corps has been able to meet depth requirements along all 400 navigable miles of the river. “But conditions we'd normally see in mid-September, we are now seeing in July.”
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