Surface passage improvements for fish now in place at all federal dams on the Lower Columbia and Snake rivers boosted the safe migration of juvenile salmon and steelhead, one of several key advances outlined in a new federal assessment of progress in protecting Columbia and Snake fish.
The passage improvements such as spillway weirs, also called fish slides, help speed young fish downstream past dams by keeping them near the water surface, where they naturally migrate. Installation of a spillway weir at Little Goose Dam on the Snake River last year means all eight federal Snake and Lower Columbia dams now provide surface passage for fish. Tests at Little Goose found that 99.4 percent of yearling chinook, 99.8 percent of steelhead and 95.2 percent of sub-yearling chinook passed the dam safely.
"Almost all of the fish are coming through the dam safely now and we're on track to meet passage standards at all of the other projects," said Witt Anderson, Director of Programs, Northwest Division, U.S. Army Corps of Engineers.
The results come from a new report describing the second year of progress by the Corps of Engineers, U.S. Bureau of Reclamation and Bonneville Power Administration in implementing NOAA-Fisheries' biological opinion for the Federal Columbia River Power System. The biological opinion outlines protections for fish affected by federal dams, promoting positive trends in salmon survival and returns. For instance, in-river survival of juvenile Snake River steelhead migrating to the ocean in 2009 reached its highest level in 12 years, a sign the fish are benefiting from improved surface passage.
Among other results in the new report:
- Federal agencies in 2009 restored water to salmon and steelhead streams that otherwise dwindle or run dry at the same time fish are returning to spawn. The 190 cubic feet per second of flow restored to streams in the Columbia River Basin last year exceeds the average amount of water consumed by Portland and nearby cities. The agencies since 2005 have protected and restored stream flows totaling more than three times the average water use of Seattle and Portland combined.
- The agencies fine-tuned spring and summer spill patterns at each dam to best help juvenile fish headed downstream. A video description is available at http://www.youtube.com/watch?v=zS_NGj79y2I
- Efforts to redistribute a large colony of Caspian terns in the Columbia River estuary helped reduce their predation on juvenile salmon and steelhead from about 15 million fish in 1999 to 6.4 million in 2009. However, double-crested cormorant predation on these fish is a growing concern, and agencies are accelerating efforts to address the issue. Together cormorants and terns consumed 17.5 million juvenile salmon and steelhead in 2009, about 15 percent of all those that reached the estuary.
- The agencies in 2009 reopened nearly 265 miles of spawning and other salmon and steelhead habitat that had been blocked by impassible culverts, diversions or other obstacles. Since 2005 the agencies have restored access to a total of 845 miles of habitat.
- "Fish are returning in numbers we haven't seen in decades and to places they haven't been for decades," said Lorri Bodi, acting vice president for Environment, Fish and Wildlife at the Bonneville Power Administration. "It's good evidence of the way states, tribes and federal agencies are working together on behalf of fish and communities."
- The biological opinion specifies performance standards for safe passage of juvenile fish past each federal dam. Tests so far indicate that results are on track to meet those standards through a combination of spill, surface passage improvements that increase the benefits of spill and other actions.
2009 FCRPS BiOp Progress Report
Video describing the biological opinion's commitment to spill
Improved Returns Demonstrate Columbia Salmon Protection
KBKW, December 27, 2010
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