Little Goose Dam Adjustable Spillway Weir arrives

Story and Photos by Gina Baltrusch The next generation of spillway weirs arrived at Little Goose Lock and Dam Oct. 30, 2017.The adjustable spillway weir (ASW), functions similarly to the fixed-height fish weirs installed at other Corps dams on the […]

Story and Photos by Gina Baltrusch

The next generation of spillway weirs arrived at Little Goose Lock and Dam Oct. 30. The adjustable spillway weir (ASW), functions similarly to the fixed-height fish weirs installed at other Corps dams on the lower-Snake and lower-Columbia rivers, allowing juvenile salmon and steelhead to pass the dam near the water surface under lower accelerations and lower pressures, providing a more-efficient and less-stressful dam passage route. As with each weir that has been developed since the first prototype was installed at Lower Granite Lock and Dam, design improvements continue to be made.  The ASW features a mechanical hoist, enabling incremental height adjustments to the weir crest to better manage water flows for out-migrating juvenile salmon during spring run-off or summer flows, or possible night operations without the use of a large crane. An overlapping water-stop panel slides in a track to move up and down with the crest component.  The ASW will replace the existing, non-adjustable, top spillway weir (TSW) currently installed in spillway bay number 1.

The next generation of spillway weirs arrived at Little Goose Lock and Dam Oct. 30, 2017.The adjustable spillway weir (ASW), functions similarly to the fixed-height fish weirs installed at other Corps dams on the lower-Snake and lower-Columbia rivers, allowing juvenile salmon and steelhead to pass the dam near the water surface under lower accelerations and lower pressures, providing a more-efficient and less-stressful dam passage route. As with each weir that has been developed since the first prototype was installed at Lower Granite Lock and Dam, design improvements continue to be made. The ASW features a mechanical hoist, enabling incremental height adjustments to the weir crest to better manage water flows for out-migrating juvenile salmon during spring run-off or summer flows, or possible night operations without the use of a large crane. An overlapping water-stop panel slides in a track to move up and down with the crest component. The ASW will replace the existing, non-adjustable, top spillway weir (TSW) currently installed in spillway bay number 1.

The next generation of spillway weirs arrived at Little Goose Lock and Dam Oct. 30. The adjustable spillway weir (ASW), functions similarly to the fixed-height fish weirs installed at other Corps dams on the lower-Snake and lower-Columbia rivers, allowing juvenile salmon and steelhead to pass the dam near the water surface under lower accelerations and lower pressures, providing a more-efficient and less-stressful dam passage route. As with each weir that has been developed since the first prototype was installed at Lower Granite Lock and Dam, design improvements continue to be made.  The ASW features a mechanical hoist, enabling incremental height adjustments to the weir crest to better manage water flows for out-migrating juvenile salmon during spring run-off or summer flows, or possible night operations without the use of a large crane. An overlapping water-stop panel slides in a track to move up and down with the crest component.  The ASW will replace the existing, non-adjustable, top spillway weir (TSW) currently installed in spillway bay number 1. (U.S. Army Corps of Engineers Illustration)

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