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T-00361: Small Stream Fish Ladders

Background: Unobstructed fish passage is key to the protection and restoration of migrating fish and their habitats. Roadways and other man-made obstructions block many fish passageways throughout the country. Fish ladders and fishways have been developed for large hydroelectric dams in the Pacific Northwest to allow salmon to migrate. But such ladders have not been developed for smallbodied fishes, such as minnows. In the Great Plains, roads intersect streams at least once per every square mile of land area, which imposes a threat on the fish population that would migrate at those crossings. Re-design of culverts to eliminate waterfalls is expensive, yet the need is extensive. Small stream fish ladders offer a relatively inexpensive and effective alternative.

Description: SDSU researchers have designed and implemented small stream fish ladders for culverts at road crossings. Experimental data have shown drastic improvement on the passage rate of small-bodied fish after installation of such ladders in chosen culvert road crossings. The addition of these fish ladders to culvert road crossings would allow for migrating fish to travel without any structural changes to existing culverts.

Advantages: This technology offers a relatively inexpensive and effective solution to the existing threat to small-bodied fish in Great Plains streams. The prototype device has been tested in the laboratory and the field and showed promising and reliable results. It is customizable and easy to install. The device is durable and requires minimal maintenance after installation. The result of the addition and usage of these ladders could greatly benefit migrating aquatic life of a region without a disruption of current roadways and culverts.