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Economic and dam related articles

New Weir Helps Fish at Little Goose Dam

by Staff
The News Tribune, April 13, 2009

STARBUCK -- Migrating juvenile salmon and steelhead are using a newly opened spillway weir in-stalled at Little Goose Lock and Dam, according to the Army Corps of Engineers.

The weir, which opened April 3, was installed as part of an effort by the Corps to improve fish survival.

"Millions of juvenile salmon and steelhead mi-grate down the Snake and Columbia rivers each spring," project manager Jack Sands said in a statement.

"This weir marks a pretty big milestone among those improvements. Surface passage facilities are now in place at all Corps dams on the lower Snake River."

A spillway weir structure is fitted into a dam's spillbay, raising the spillway opening to create a surface-oriented passage for out-migrating fish.

Juvenile salmon and steelhead can safely pass over a raised spillway crest more efficiently than with conventional spill while reducing migration delays at the dam, the Corps said.

The spillway weir will be tested during the 2009 fish passage season to evaluate how many fish are using the spillway weir, as well as the juvenile passage survival.

(bluefish notes: Juvenile survival by spillway passage at Little Goose is already estimated at 100% survival. Other spillway weirs have been installed on the Lower Snake River dams but adult return data has yet to reveal any survival benefits. Surprisingly, no experiments were ever designed.)


Hi Scott,

From your email I couldn't tell if you had gotten our memo to you responding to your questions that we sent last September. If not, the link is below -

www.fpc.org/documents/memos/146-08.pdf

In the memo we noted that none of the studies we reviewed included an adult survival component "While juvenile survival may have improved at this project, it is unknown if this specific operation has had an effect on survival to adulthood since no specific studies have been conducted." So you are correct that there is no adult return evidence.

I also have attached the final report from the 2007 studies that were conducted at Little Goose Dam in case you didn't already have it.

Let me know if this helps -

Margaret J. Filardo, Ph.D.
Fish Passage Center
1827 NE 44th Ave Suite 240
Portland, OR 97213


Staff
New Weir Helps Fish at Little Goose Dam
The News Tribune, April 13, 2009

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