The Las Vegas Wash carries more than 200 million gallons of water per day, connecting the Las Vegas Valley with Lake Mead, our community’s primary source of drinking water. The Wash is fed by reclaimed water, urban runoff, shallow groundwater, and stormwater. Wetlands at the Wash serve as “nature’s kidneys,” cleaning the water running through them by filtering out harmful contaminants.
The lower, approximately four-mile stretch of the Wash (between Lake Las Vegas and the confluence with the Colorado River), experiences high rates of erosion and channel degradation when Lake Mead’s water surface is low. If current rates of erosion are left unchecked, the Lower Wash channel will continue to degrade resulting in increased water quality issues in Lake Mead. The Southern Nevada Water Authority has been designated as the lead agency to coordinate and manage the enhancement of the Wash and has identified several erosion control structures, channel bed and bank stabilization, and revegetation efforts that need to be installed in the Lower Wash to provide long term stabilization.
The schedule for the Lower Wash will require a phased approach, preliminary and final design of project components will initially focus on access roads, followed by grade control structures (weirs), stabilization and revegetation components, in sequential order from upstream to downstream. Final construction of all grade control structures, and revegetation efforts are planned to be completed by January 2030.
To help the Las Vegas Wash degradation and erosion, GES performed the following services on the following projects.
Las Vegas Wash North Channel – The project included improvements to approximately 2,600 linear feet of drainage channel. The improvements included lining the existing earthen channel with concrete to create a trapezoidal channel, and construction of an unpaved access road adjacent to the new channel. The site is bounded to the north by Gowan Road, to the east by the Community College of Southern Nevada – Cheyenne Campus, to the west by residential and commercial developments, and to the south by Cheyenne Avenue. GES provided a geotechnical evaluation to provide general subsurface information and recommendations to aid in the design and construction of the proposed improvements to the existing wash. The scope of this study included a review of referenced geologic literature and maps, subsurface explorations, soil sampling, laboratory testing of selected soil samples, engineering evaluations, and preparation of this report.
Las Vegas Wash Channelization – GES performed two full scale aquifer pump tests, preparing a dewatering plan and specification, and updating/finalizing the drafted geotechnical investigation report.
Las Vegas Wash Monitoring Well Installation – GES installed three temporary monitoring wells to a depth of 35 feet each for a total well footage of 105 lineal feet and presented a summary report with the data retrieved from the groundwater samples taken from the site. GES also sampled surface water flowing with the Las Vegas Wash from two locations. The samples were then sent to the lab to perform chemical analysis. Lastly, GES drilled 3 additional borings, two (2) to forty feet and one (1) to 35 feet. Soils samples were obtained using ring samplers and lab tests were performed.
Las Vegas Wash Groundwater Testing and Analysis – Based on the Clark County Water Reclamation District’s revised dewatering evaluation report and project specifications GES was contracted to update the initial geotechnical evaluation report to reflect the changes to the project and add recommendations for construction of the new containment structure and access road pavement section. GES also prepared 100 % document geotechnical plan review letter after the project plan revisions were finalized.