Session A4- Lower Yellowstone River fish passage and entrainment prevention

The Lower Yellowstone Irrigation Project near Glendive, MT, has supplied irrigation water for approximately 54,000 acres of fertile land for over 100 years. The diversion dam presents a passage barrier to the endangered Pallid sturgeon (and other native species) while the unscreened intake allows fish to become entrained in the canal system. An ongoing joint effort between the U.S. Army Corps of Engineers and the U.S. Department of the Interior, Bureau of Reclamation aims to address both the passage and entrainment issues. Entrainment prevention is being addressed through the use of screened intakes on a new headworks structure that is currently under construction. The hydrologic variability of this relatively free-flowing large river and frequent severe ice floes bring unique challenges to the design of fish screens. Numerous fish passage options have been evaluated including bypass channels and a rock ramp. In addition to one- and two-dimensional numerical modeling, 1:20 scale physical models of the rock ramp have been employed to evaluate fish passage criteria. Bypass channel options have been evaluated using one-dimensional numerical modeling. The focus of this presentation is the comparison of results from numerical and physical modeling for multiple alternatives based on depth and velocity criteria