(from USGS Nevada) Lake Mead on the Colorado River is one of the most intensely used reservoirs in the western United States, providing recreational watercraft activities and domestic drinking, industrial, and irrigation water for over 22 million users. The quality of this water must be maintained to guarantee a reliable and safe resource for its many uses. Inflow into Lake Mead primarily is from the Colorado River; however, about 3 percent of the inflow is from tributaries on the northern side of the Lake and from Las Vegas Wash on the northwest side of the Lake.

Las Vegas Wash transports treated municipal wastewater effluent, stormwater and urban runoff, and shallow ground-water seepage from the Las Vegas urban area to Las Vegas Bay of Boulder Basin in Lake Mead. Water in Lake Mead eventually evaporates, flows through Hoover Dam, or is intercepted by pump intakes for the municipal water treatment plant at Saddle Island. Efforts are currently underway to improve the quality of water in Las Vegas Wash before it discharges to Lake Mead. Additionally, the Las Vegas Wash Coordination Committee, a multi-agency panel chaired by the Southern Nevada Water Authority, is working to stabilize the Las Vegas Wash Channel, establish wetlands along Las Vegas Wash, perform environmental monitoring, and promote public awareness by disseminating timely monitoring results.

The U.S. Geological Survey (USGS), in cooperation with the Southern Nevada Water Authority (SNWA) and Bureau of Reclamation (BOR), is monitoring water-quality on a "real-time" basis in Lake Mead at two locations, Las Vegas Bay and Sentinel Island.