2014 Las Vegas Wash Time-of-Travel Study

Project ID: 2262
Principal Investigator: Kevin Kelly
Research Topic: Ecosystem Needs
Funded Fiscal Years: 2015
Keywords: las vegas wash, erosion, wetlands, water quality, dye tracing, time-of-travel

Research Question

How has the morphometry of Las Vegas Wash (NV) changed since Reclamation carried out studies during the 1980s?

Need and Benefit

The Wash was formerly an ephemeral stream prior to its use as a wastewater outlet. It now carries approximately 200 million gallons of water per day into Lake Mead. Reclamation has performed extensive studies over 30 years documentating the impact the Wash has on the water quality and limnology of Lake Mead. Since 2000, a Capital Improvements Plan was initiated to construct erosion control structures (weirs) on the Wash between the three upstream wastewater treatment plants and Lake Las Vegas. Construction is on-going with the last weirs expected to be completed in 2017. As a result, the morphometry of the Wash is expected to have changed significantly.

In 2012, Janet Kirsch (LC Regional Office) proposed a Research Jam idea of doing another time-of-travel dye tracing study on the Wash. The objective of this study is to determine the change in the time-of-travel in the Wash based on the techniques used in the previous studies using a plug of Rhodamine WT as a tracer dye. This task is being planned to take place during November, 2014, which is during the same time frame previous dye studies were performed.

Information from this work will support of a number of other related Reclamation projects including water quality, demonstration wetlands, groundwater discharge modeling, and erosion control.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Las Vegas Time of Travel Study (final, PDF, 2.1MB)
By Becky Blasius
Publication completed on September 30, 2016

This study estimated travel time for the Las Vegas Wash (Wash) and compared the results with previous travel time measurements. Travel times were measured using a fluorescent Rhodamine WT 20 dye. Dye concentration was collected at 10 sampling sites using multiprobe dataloggers with Rhodamine sensors. The raw data were corrected for background measurements of Rhodamine concentration and analyzed to determine travel times and velocities. The average travel time for water through the Wash between Vegas Valley Drive and Site S8 located near the Las Vegas Marina boat launch was 14.23 hours. For the reach between the confluence of the Wash with discharges from the Clark County Water Reclamation District's (CCWRD) Central and Advanced Wastewater Treatment Facilities and the Northshore Road bridge, the travel time was approximately 9.6 hours. The average velocity of water in the Wash was one mile per hour. Compared with travel times from previous studies, the travel time observed in this study is an intermediate value between the travel time observed in 1980 and the time observed in 1986, indicating that construction of weirs and vegetation establishment over the last 15 years has slowed the average velocity of water in the Wash and increased the travel time.

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Last Updated: 6/22/20