Research on the Yampa River seeks to slow spread of highly invasive plant

Eleanor C. Hasenbeck/Steamboat Pilot & Today
Landowners and managers take a close look at leafy spurge while walking through a dense patch of it during an awareness raising tour held in June near Craig.
Sasha Nelson/staff

At a glance

Organizations collaborating to manage leafy spurge on the Yampa River include:

  • Moffat and Routt County Board of County Commissioners
  • Moffat and Routt County Weed Programs
  • Bureau of Land Management
  • Dinosaur National Monument
  • Colorado Parks and Wildlife
  • University of Wyoming
  • Community Agricultural Alliance
  • The Nature Conservancy
  • Natural Resources Conservation Service Colorado First Conservation District
  • Friends of the Yampa
  • Yampa/White/Green Roundtable
  • Landowners in Routt and Moffat County

HAYDEN — Since the 1960s, leafy spurge has been spreading downstream on the Yampa River west of Hayden.

The noxious weed, with its clusters of yellow flowers, is toxic to deer, elk, and cattle in high quantities. The plant out-competes native species and crops, choking out other plants on the riverbank and reducing the economic value of the hay meadows it creeps into.

A new research project out of the University of Wyoming will explore how best to manage the weed and slow its spread on the Yampa.

The project, led by Daniela Tekiela, a Wyoming professor and invasive plant extension specialist, aims to identify where exactly leafy surge is growing on the river and to find the best ways to stop its spread. The information could help manage the infestation in the Yampa Valley, but it could also stop the spread of the weed in other parts of the nation, too.

An $89,000 grant from the Yampa/White/Green River Basin Roundtable along with matching funds from the Yampa River Leafy Spurge Project has funded the three-year research project.

Leafy spurge has infested almost 2,000,000 acres of agricultural lands in Montana and North Dakota, according to the Yampa River Leafy Spurge Project. In Wyoming, Tekiela said, leafy spurge has invaded to the point that managers don’t have hopes of reducing the amount of leafy spurge growing.

“That’s really not a place you want to be,” Tekiela said. “What’s really interesting in the Yampa River area is that currently leafy spurge is really only restricted to that riparian corridor there, so that kind of wet, vegetated area along the riverway.”

This is typical of an early invasion, he said.

Once it advances, leafy spurge invades pasture and rangeland. Once there, it outcompetes alfalfa and other crops and can lead to a decline in the economic value of agricultural land. Insects, deer, and elk also avoid areas where leafy spurge is growing, because they don’t like to eat it.

“On the Yampa River, we don’t have that,” he said. “So, we have the opportunity to reduce the population to a point where hopefully it never happens.”

For this reason, Yampa River Leafy Spurge Project member Ben Beall encourages ranchers and other producers to get involved with the project, which meets every other month at the Carpenter Ranch.

Leafy spurge grows on the banks of the Yampa River.

“It’s their land where the infestations are,” Beall said. “We’re working with them to get permission for access and things like that.”

The research project has two components.

First, researchers will work to find the best way to manage the plant on the riverbanks.

Fighting an invasive plant in the riparian areas along the river’s banks presents several challenges. Concerns for water quality mean managers must be careful using herbicide on the weeds. As the water rises, it can carry seeds downstream, spreading the infestation.

“You get a bunch of seeds sitting on the soil surface,” Tekiela said. “You get a flooding event. It lifts those seeds off, moves them downstream and starts to deposit them. They started to notice that happening more and more in Dinosaur National Monument, and that was kind of the rationale for trying to do something about this because it seems like there’s this critical threshold that’s been reached where the spreads really taking off.”

A map showing outbreaks of leafy spurge along the middle and lower Yampa Rivers.

The name of the game in leafy spurge management is stopping the seed from spreading. The researchers will test different ways of managing this spread, including targeted sheep and goat grazing, herbicide use where it is safe to do so and the use of biocontrol.

Biocontrol uses a predator of leafy spurge, the aptly named leafy spurge beetle, to try to consume the plant. The beetles target the leafy spurge without damaging other plants. However, Tekiela said the beetles tend to be more successful on dry, upland sites, as the beetle burrows into the root of the plant during one stage of its life cycle. If the root is in wet soil, such as the banks of the Yampa, the beetles don’t always survive.

The Yampa River Leafy Spurge Project has already released some beetles into infested sites, but no monitoring has been done to see how many of the bugs lived, said Beall.

“We know that some of them have survived, and if we can get them to survive, we could harvest our own beetles and release them in other plots,” Beall said. He also hopes to get kids and the community as a whole involved in monitoring beetle release sites.

Tekiela’s team will test if any combination of grazing, herbicide, and biocontrol proves more fruitful in slowing the spread of seeds than the others.

“We’ll monitor different treatments of different timings of grazing with different herbicides and see if any combination of those will reduce the amount of seeds being produced by leafy spurge,” Tekiela said

Second, Tekiela’s team and leafy spurge project volunteers will work to learn exactly where the plant is infesting the river.

“The more challenging thing is knowing where to focus your efforts because the reality is we don’t have enough money, enough people or enough hours in the day to be able to manage all of the leafy spurge, even on the Yampa River, within a single year, and it’s hard to know exactly where it is,” Tekiela said.

Tekiela’s team wants to learn if satellites and other remote sensing equipment can help learn exactly where the leafy spurge is infesting the land. This will be used to build a database of where the weed is growing along the riverbank.

Tekiela will combine this data with data collected from other leafy spurge infestations across the nation to try to build a model that can predict where leafy spurge will spread next based on information about precipitation, soil types and other factors.

Beall said the public can help by reporting infestations of leafy spurge to the Yampa River Leafy Spurge Project or their county weed program.

To learn more about the Yampa River Leafy Spurge Project, including how to identify the plant, visit You can report infestations there or by contacting the Routt County Weed Program at 970-870-5246 or the Moffat County Weed Program at 970-824-9180.

To reach Eleanor Hasenbeck, call 970-871-4210, email or follow her on Twitter @elHasenbeck.

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