Sunday, Aug. 27, 2017 | 2 a.m.
Like the rugged slopes of Mount Charleston or the crimson crags of Red Rock, the Las Vegas Wash is one of Southern Nevada’s original inhabitants.
For millions of years, the wash has acted as a natural release valve, funneling floodwaters away from the valley.
Thanks to a conservation campaign and a modern trail system, the wash is in its best shape in decades.
“More people ... now have a very personal experience with the Wetlands Park because it is quite literally their backyard,” said Debbie Van Dooremolen, an environmental biologist for the Southern Nevada Water Authority.
But it’s more than just a ribbon of green in the dry desert. The wash and the wetlands through which it flows serve a vital role in the community.
History
As recently as the 1980s, the amount of dirt flowing through the wash was enough for state water regulators to list the channel as an “impaired water source.” Due to ongoing conservation efforts, water quality has rebounded.
Flowing water from storms and springs in the area gradually carved out the channel, but for most of its history, the wash only occasionally carried water. It was an ephemeral stream, only flowing after natural events, and even then only briefly. The arrival of humans in the valley, first Native Americans thousands of years ago and then Spanish explorers in the 1800s, sparked the beginning of a shift in the role of the wash. With the railroad-based population boom, construction of the Hoover Dam and the birth of the gaming industry, water usage spiked and the wash swelled with it.
“All of a sudden, we had perennial flows that turned it into a stream,” said the SNWA’s Van Dooremolen. “It’s more like Las Vegas River, but we call it Las Vegas Wash because that’s what we always had.”
The more water that flowed through the channel, the faster the current, which began to cause erosion that affected water quality. The wash and surrounding wetlands grew even bigger over the decades, with fast-moving flows scouring out river banks and saturating the water with dirt and sediment that eventually made its way into Lake Mead. In 1998, the problem became so dire that community leaders formed the Las Vegas Wash Coordinating Committee (LVWCC) to address it.
What does it do?
The kidneys
The wash and the wetlands are commonly called the “kidneys” of the local environment; they naturally flush out organisms and solids that might be harmful to the health of both humans and the ecosystem.
Simply put, the wash helps treat our water. It and the wetlands are home to hundreds of different plants, many of which “trap” the sediment and toxins flowing in the water.
Dump a handful of dirt in a clean glass of water. That’s basically what erosion does to water quality, says Van Dooremolen. Wherever the water flows, the dirt is deposited. In our case, that’s Lake Mead, the main source of water for the city. Other contaminants include water from residential and industrial sources, which gather pesticides, oil and bacteria on roads and eventually find their way to the wash.
Where is it?
Man-made flood channels snake their way all over the city, but the bulk of the natural wash consists of a 12-mile stretch between where the wash enters the wetlands near Vegas Valley Drive and where it ends at Las Vegas Bay.
You can visit the wash at Wetlands Park at 7050 Wetlands Park Lane. The nature center and exhibit hall are open from 9 a.m. to 4 p.m. daily. The trails are open from dawn to dusk.
The future
Fast facts
• The wash spanned 2,000 acres at its height during the 1950s and through the 1980s. In the 1990s, after significant erosion, it was down to 200 acres.
• The wash also constitutes 2 percent of Lake Mead (with 97 percent coming from the Colorado River and 1 percent combined from the Muddy River and Virgin River).
• Major water sources for the wash include 85 percent highly treated wastewater (treated sewage); 15 percent urban runoff (from yards, businesses, etc.) and shallow groundwater; and stormwater when it rains and floods.
As the wash and wetlands have grown, so has the public’s awareness of related issues. Housing developments now abut much of the wetlands’ 2,900 acres of protected land, and the area sees a lot of visitor traffic. After all construction and replanting projects are completed, the main goal will shift to long-term maintenance. “We need to protect that investment in the channel,” Van Dooremolen said. “Ten years from now, we’ll still be out there getting things done.” Conservation efforts by the LVWCC, backed by the SNWA, have been working to prevent erosion, rebuild habitats and improve water quality in the wash since 1999. The key features are:
• Slowing erosion: 19 out of 21 planned weirs — man-made structures that slow rushing water — have been constructed along the wash. One is under construction, with another out for bid.
• Replanting: The committee organizes public replanting events every year with the aim of strengthening the wash ecosystem. Vegetation acts as a sort of armor for the soil, leading to less erosion and more opportunity for wildlife such as fish and birds to flourish. So far, about 500 acres have been replanted.
• Planning for climate change: Climate models predict increased rainfall for the Southwest because of ongoing climate change, which may or may not end up affecting the wash, Dooremolen says. “When you’re talking about potential increases in large storm events, that could mean we’ll be facing some erosion issues again,” she said. “That could mean we’re dealing with significant weir repairs, and we’ll maybe have to go back in and replant vegetation that gets scoured out.”
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