The Issues
Over the past 30 years, erosion has destabilized the Wash channel and caused increased sedimentation in Lake Mead. The Comprehensive Adaptive Management Plan developed by the Las Vegas Wash Coordination Committee (LVWCC) identifies stabilizing the Wash as one of three key initial steps needed for long-term management of the Las Vegas Wash. As a result, the LVWCC has developed the Las Vegas Wash Capital Improvements Plan, which will help to stabilize the channel over the years.
Demonstration Weir
One way to deal with erosion is by placing erosion control structures (which are also known as grade control structures or weirs) throughout the Wash. In total, 22 structures are planned for the Wash. As of January 2008, 11 weirs are in place, and construction will soon be completed on the twelfth. As we succeed in stabilizing sections of the channel, we develop additional riparian and wetland habitat. The erosion control structures help slow the water, creating a pond behind the structures in which wetland plants can establish. Weir construction activities also clear acres of invasive plants such as tamarisk from the banks of the Wash. These cleared areas are then revegetated with native wetland, riparian, and upland species.
Downstream of Rainbow Gardens Weir
Achieving Equilibrium
Addressing conditions such as: increasing and variable daily flows, highly erodable soils, water quality concerns, the need to protect wildlife habitat, and other environmental concerns present formidable challenges to controlling erosion in the Wash. However, efforts are currently under way to promote channel stabilization by decreasing channel bed downcutting, reducing stream bank erosion, armoring the channel with vegetation, balancing sediment transport and enhancing the ecosystem.
TABLE 1 GENERAL LAS VEGAS WASH DESIGN GOALS | |
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Present Conditions
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Stable Conditions
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