Design of a semi-permeable fish control structure used for hydrologic restoration

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Experimental analysis is performed in this study to determine the appropriate size of material for a semi-permeable fish control structure that the U.S. Bureau of Reclamation is proposing along the Colorado River between Beal Lake and Topock Marsh. This type of control structure will allow sufficient water to pass through and meet the demands of the downstream pumping system that is used for hydrologic restoration, while at the same time, preventing nonnative predatory fish larvae and eggs from passing through the structure. This study is unique in that most previous studies have focused on prevent large organisms from passing through the control structures. Experiments were performed in the UNLV Hydraulics Laboratory to determine whether fish larvae or eggs will pass through the structure. Fish egg surrogates that have a diameter of approximately 0.8 to 1.0 mm were used in the laboratory. Preliminary results suggest that 0.375 inch material is able to filter 100% of a fish egg surrogate, and 0.5 inch material is able to filter approximately 95% of the fish egg surrogate. This size material is sufficient to meet downstream hydraulic demands. Future studies will focus on the overall design of a composite filter with various gradation of material and the investigation of the potential clogging of the filter will be investigated in field tests.


Beal Lake; Colorado River; Filters; Fish control structures; Groundwater hydrology; Invasive species; Topock Marsh; Wetlands


Environmental Health and Protection | Environmental Sciences | Fresh Water Studies


Presented at the American Geophysical Union, 2000 Fall Meeting, San Francisco, California, December 15-19.


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