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Effect of backwatering a streamgage weir on the passage performance of adult American Shad (Alosa sapidissima)

July 7, 2021

Streamgage designs often include a full-width artificial hydraulic control (e.g., concrete weir) to aid in the computation of streamflow. While important to water resource managers, these weirs also tend to act as full or partial barriers to fish migration, effectively hindering the health and survival of these populations. In this study, we conducted experiments to quantify the effect of head drop and submergence of a common streamgage weir on the passage performance of an important migratory fish species, the American Shad. Three treatment conditions were selected based on the tailwater surface elevation (ElTW): unsubmerged (ElTW = 1.05 m; head drop = 0.46 m), equal to the weir crest (ElTW = 1.20 m; head drop = 0.31 m), and submerged (ElTW = 1.36 m; head drop = 0.15 m). Fish movements were recorded via passive integrated transponder telemetry techniques. Results revealed that the backwatered Columbus-type weir was not a complete barrier at any of the three treatments, but passage was shown to be significantly impaired when the weir was unsubmerged. Passage efficiency for the unsubmerged, equal, and submerged treatments was 20.2 ± 6.2, 49.2 ± 7.2, and 64.2 ± 7.4%. Backwatering a weir, rather than removal or other major alterations that would affect weir calibration, may be an acceptable retrofit to increase fish passage.

Publication Year 2021
Title Effect of backwatering a streamgage weir on the passage performance of adult American Shad (Alosa sapidissima)
DOI 10.1080/24705357.2021.1945500
Authors Kevin Mulligan, Alexander Haro, John Noreika
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Ecohydraulics
Index ID 70221871
Record Source USGS Publications Warehouse
USGS Organization Eastern Ecological Science Center