$2.6M project to reduce erosion on Las Vegas Wash to begin in January
WATER QUALITY
The Southern Nevada Water Authority will begin work on a $2.6 million project in January to fix a series of “aquatic speed bumps” that reduce erosion along the Las Vegas Wash.
The bumps — called weirs — slow the flow of water as it runs over them and require regular maintenance.
They’ve been overtaken by vegetation, with plants growing on the weirs that can cause cracks along concrete and ultimately affect water quality.
The wash takes the valley’s excess water and returns it to Lake Mead. It carries more than 200 million gallons daily, according to the Southern Nevada Water Authority.
There are 21 weirs along the 12-mile wash, which carries the treated water through the 2,900-acre Clark County Wetlands Park and then two culverts underneath Lake Las Vegas on the way to Lake Mead.
A few of the weirs are solid concrete structures, but most are made of rip-rap, a layer of rock and recycled concrete from parking lots of imploded casinos like the Stardust, El Rancho and Landmark. It is on top of the riprap where vegetation grows.
Sediment builds on the rock, making water weave around rather than go in one direction, said Jason Eckberg, an environmental biologist for Southern Nevada Water Authority.
Beginning in January, Las Vegas Paving Corp. will complete the project.
“It’s not ‘set it and forget it,’ ” said Bronson Mack, a spokesperson for the Southern Nevada Water Authority. “It’s set it, and then care for it.”
Since construction of the weirs started in 1998, the amount of sediment in the water heading to Lake Mead from the wash has been reduced by about 70%, Eckberg said.
“Everything that gets eroded away goes into Lake Mead and then that affects water quality,”
Mack said. “Preventing erosion here is protecting water quality.”
About 90% of the water flowing through the wash is treated wastewater, Eckberg said. The rest is primarily shallow groundwater and urban runoff from storms.
A top priority is removing phragmites australis — an invasive species of flowering plant that can grow up to 20 feet tall — forming dense stands and displacing wildlife habitat, according to the U.S. Department of Agriculture.
The project will also remove large trees, like willows and cottonwood, from areas around the weirs. As roots from those trees grow, they move rocks, Eckberg said.
Some softer vegetation, like cattails and reeds, will also be removed because of sediment build up.
Eckberg said the project additionally called for bank reinforcement to prevent erosion near the Nature Center, a 30,000-squarefoot exhibit, classroom and auditorium facility at the Clark County Wetlands Park.
The area has cultural significance because Native American settlers used to make storage pits there to keep food in a more controlled environment, especially during the summer, Mack said.
The structures have been rebuilt and are in the Clark County History Museum. ilana.williams@gmgvegas. com / 702-948-7836 / @ilana_willi
The bumps — called weirs — slow the flow of water as it runs over them and require regular maintenance.
They’ve been overtaken by vegetation, with plants growing on the weirs that can cause cracks along concrete and ultimately affect water quality.
The wash takes the valley’s excess water and returns it to Lake Mead. It carries more than 200 million gallons daily, according to the Southern Nevada Water Authority.
There are 21 weirs along the 12-mile wash, which carries the treated water through the 2,900-acre Clark County Wetlands Park and then two culverts underneath Lake Las Vegas on the way to Lake Mead.
A few of the weirs are solid concrete structures, but most are made of rip-rap, a layer of rock and recycled concrete from parking lots of imploded casinos like the Stardust, El Rancho and Landmark. It is on top of the riprap where vegetation grows.
Sediment builds on the rock, making water weave around rather than go in one direction, said Jason Eckberg, an environmental biologist for Southern Nevada Water Authority.
Beginning in January, Las Vegas Paving Corp. will complete the project.
“It’s not ‘set it and forget it,’ ” said Bronson Mack, a spokesperson for the Southern Nevada Water Authority. “It’s set it, and then care for it.”
Since construction of the weirs started in 1998, the amount of sediment in the water heading to Lake Mead from the wash has been reduced by about 70%, Eckberg said.
“Everything that gets eroded away goes into Lake Mead and then that affects water quality,”
Mack said. “Preventing erosion here is protecting water quality.”
About 90% of the water flowing through the wash is treated wastewater, Eckberg said. The rest is primarily shallow groundwater and urban runoff from storms.
A top priority is removing phragmites australis — an invasive species of flowering plant that can grow up to 20 feet tall — forming dense stands and displacing wildlife habitat, according to the U.S. Department of Agriculture.
The project will also remove large trees, like willows and cottonwood, from areas around the weirs. As roots from those trees grow, they move rocks, Eckberg said.
Some softer vegetation, like cattails and reeds, will also be removed because of sediment build up.
Eckberg said the project additionally called for bank reinforcement to prevent erosion near the Nature Center, a 30,000-squarefoot exhibit, classroom and auditorium facility at the Clark County Wetlands Park.
The area has cultural significance because Native American settlers used to make storage pits there to keep food in a more controlled environment, especially during the summer, Mack said.
The structures have been rebuilt and are in the Clark County History Museum. ilana.williams@gmgvegas. com / 702-948-7836 / @ilana_willi