The Las Vegas Valley is the Large MS4 in southern Nevada. After consulting with local stakeholders, NDOT selected a monitoring site on the Las Vegas Wash at LW11.5. The Las Vegas Wash is the sole drainage from the entire Las Vegas Valley to Lake Mead and contributes approximately 1.5 percent of the total flows to the lake. Water quality protection in the Las Vegas Wash is crucial because any contaminants will eventually enter Lake Mead and could pollute the drinking water source for the Las Vegas Valley.
This monitoring site is co-located with the Clark County Regional Flood Control District’s upstream wet weather monitoring station. This monitoring site provides information on an area with Nevada’s largest urban population. LW11.5 is located upstream of the waste water discharges. Therefore, LW11.5 only has three flow inputs: urban runoff, shallow groundwater, and storm flows. This reach of the Las Vegas Wash was initially placed on Nevada’s 303(d) List of Impaired Waters for Total Dissolved Solids (TDS), boron, and selenium during the 2008-2010 reporting cycle.
Discharge, gage height, and precipitation data is collected at USGS gaging station 094196783 located approximately 0.2 miles upstream of the Las Vegas Wash monitoring station.
Air temperature and humidity data is collected at the Las Vegas Wash monitoring station.
The water quality standards that apply to this segment of the Las Vegas Wash can be found here:NAC 445A.2156.
Note: This site is designed to collect measurements of storm flow in the Las Vegas Wash. Therefore, when runoff from precipitation events is not flowing in the Las Vegas Wash, the sensors will not be submerged in water and will be measuring the air.