Posing both fire and flooding threats, invasive tamarisk being removed along Virgin River in Mesquite

ST. GEORGE — Workers contracted by the Bureau of Land Management began clearing large clumps of tamarisk growing along the Virgin River in Mesquite on Friday as part of a fire fuels reduction effort. The invasive species is not only a fire danger but also a concern for flooding and is considered one of the causes of the damage wrought by the 2005 Santa Clara River flood.

Excavators contracted by the BLM are outfitted with special masticating heads to clear tamarisk by the Virgin River, Mesquite, Nevada, April 14, 2021 | Photo by Ammon Teare, St. George News

Frank Rice, fuels technician for the Southern Nevada District of the Bureau of Land Management, told St. George News that the work in Mesquite would continue for several days.

“The goal is to reduce the fire danger by lowering the profile of the tamarisk,” Rice said. “It’s very flammable, and it’s so thick that it poses a significant fire danger so close to the town. It would also help restore native species.”

Rice said the excavators and crews working to clear the tamarisk in Mesquite had been contracted through Giles Construction of Tooele. The crews were clearing tamarisk at six sites, totaling 50 acres of clearing.

Tamarisk, or salt cedar, is a deciduous tree known for its affinity for water and the pink flowers it puts out between March and September. It can grow to almost 30 feet in height, with trunks as wide as 15 feet.

Native to the Middle East, as well as other arid parts of Europe and Asia, tamarisk flourishes in hot, sandy conditions along rivers and streams. First introduced to the United States as early as the 1800s, the trees were even planted in the millions by the federal government to reduce erosion during the Dust Bowl.

A close-up view of a tamarisk branch, St. George, Utah, April 15, 2021 | Photo by Ammon Teare, St. George News

With the benefit of hindsight, this mass planting, along with its natural spread, has led to salt cedar becoming one of the most prevalent and harmful invasive species along waterways in the Western United States.

Steve Meismer, local coordinator for the Virgin River Program, said that tamarisk is highly flammable, even when healthy and green. Another threat imposed by tamarisk overgrowth is an increased risk of flooding.

“In the 2005 flood of the Santa Clara River, there were 23 homes lost,” Meismer said. “The homes weren’t lost because of flooding. They were lost because of erosion. The river basically ate the ground out from below the houses, and the reason that happened is you had tamarisk that had grown across the Santa Clara River.”

In that event, the narrow channel of the Santa Clara River at the time was clogged by the rigid stalks of tamarisk, Meismer said, and when flood waters rushed down they were diverted underneath nearby homes.

After that catastrophe, local municipalities were much more willing to invest in treatment plans. Tamarisk remains almost omnipresent around water sources, but it has been cut back significantly and may be declining slowly thanks to restoration efforts.

A view of the Virgin River basin with a canal in the foreground and abundant tamarisk growing along the banks, Mesquite, Nevada, April 14, 2021 | Photo by Ammon Teare, St. George News

Salt cedar is named for its ability to excrete salts concentrated in its leaves that eventually accumulates in the topsoil. The resulting salty soil is intolerable for many native plants and may contribute to accelerated erosion over time.

In contrast, native species like willow and cottonwood are much better suited for slowing floodwaters, anchoring riverbanks and making the area around rivers more suitable for a variety of plant and animal species. However, restoring native trees and river systems is more difficult than just taking out tamarisk, Meismer said.

“We could take out tamarisk any day of the week,” Meismer said. “But we want to be able to not leave a void in the environment for too long on the chance that something else that we don’t want may take advantage of it.”

According to a press release from the BLM, the project in Mesquite will be completed in three phases. The first phase, currently underway, will consist of 1-2 weeks of clearing. In about a year, specialists from the National Park Service will treat the cleared area with herbicides targeted at killing tamarisk sprouts.

Finally, seedlings of native trees grown near Lake Mead will be planted and then monitored for a number of years after that.

The willow flycatcher, location and date not specified | Photo courtesy of Utah Division of Wildlife Natural Resources, St. George News

The Virgin River Program has not undertaken any large-scale efforts to remove tamarisk in Southern Utah in the past couple years, Meismer said. This is mostly due to limited funding, not only to cover the costs of removal but also subsequent herbicide treatments and replanting.

Another challenge for removing tamarisk is the potential harm to endangered and threatened species that may nest in tamarisk thickets. Meismer said they are particularly concerned about the southwestern willow flycatcher, a small bird native to the Southwest that’s been federally designated as endangered since 1995.

In areas where the flycatcher has been observed, crews are particularly careful, Meismer said, and removal may be done by hand only to avoid disturbing any nests.

Copyright St. George News, SaintGeorgeUtah.com LLC, 2021, all rights reserved.

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