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Water: Nonpoint Source Success Stories

Nevada: Las Vegas Wash

Best Management Practices Drastically Reduce Sediment and Restore Water Quality in Las Vegas Wash

Waterbody | Problem | Project Highlights | Results | Partners & Funding

Waterbody Improved

nv_circleThe Las Vegas Wash drains the 1,600-square-mile Las Vegas Valley, delivering stormwater, urban runoff, and highly treated effluent to Lake Mead, the nation's largest manmade reservoir and the primary water supply for millions of people in Nevada, Arizona, and southern California. These sources caused water quality impairments to the lower wash due to excess sediment and iron transported with that sediment. In 2002, Nevada placed the lower reach of Las Vegas Wash on its 303(d) list of impaired waters, with impairments to aquatic life propagation (excluding fish) due to total suspended solids (TSS). Following the construction of erosion control structures, restoration of wetland areas, and removal of invasive vegetation, average TSS concentrations declined significantly. This allowed the state to remove the lower reach from its 303(d) list in 2004.

 

As of June 2006, the project has involved constructing nine weirs, stabilizing more than 21,000 linear feet of streambank, restoring 33 acres of wetlands, and removing 500,000 pounds of trash and 680 acres of tall whitetop.

While project water quality benefits had begun to be realized before 2002, the lower reach of the wash did not meet the 5-year threshold criteria for TSS and was therefore placed on the 2002 Nevada 303(d) list. Water quality improvements continued, however, with average TSS concentrations declining 50 percent since 2001. Analysis of 1999–2003 water quality data showed that TSS concentrations exceeded the 135 mg/L standard 11 times out of 130 samples collected. This represented an 8.5 percent noncompliance rate, below the maximum 10 percent allowable rate.

With TSS data showing compliance with water quality standards, Nevada removed the lower reach's aquatic life propagation (excluding fish) impairment from its 303(d) list in 2004. The NV DEP will continue to review monitoring data to confirm continued compliance with water quality standards.

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Partners and Funding

The cooperation of 28 members of the LVWCC, representing local, state, and federal agencies, local environmental groups, businesses, and interested citizens, was essential in the creation of a comprehensive management plan for the Las Vegas Wash. Volunteers also played an important role in the project, providing the needed labor for wetland and riparian plantings and invasive vegetation removal. The overall cost to implement the CAMP is projected to be approximately $127 million through 2013.

As of 2006, $33 million has been spent on CAMP implementation. Approximately $600,000 of section 319 funds was used to support construction of erosion control structures, bank revegetation, and public outreach efforts. Participating agencies contributed $1.8 million during the 2005–2006 fiscal year.

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