Weed Them Out: Big Horn County Weed & Pest removes Russian olives

Big Horn County Weed and Pest Control [BHCWP], in conjunction with an array of local, state, and federal agencies, has begun the removal of the Russian olive trees throughout Big Horn County.
The Russian olive is an invasive species of ornamental tree that was introduced to the central and western United States in the late 1800s, where it has often served as a windbreak. Highly adaptive, the species has since displaced a number of native plants and driven down ecological diversity.
Cliff Winters, BHCWP District Supervisor, explained that they developed and started their remediation plan in 2023 and are now roughly 50% of the way through the first phase of their removal program. Working with nine different land owners, land managers, the South Big Horn Conservation District [SBHCD], Natural Resources Conservation Service [NRCS], state and federal forestry services, and the Bureau of Land Management [BLM], Winters and BHCWP have removed several hundred acres worth of Russian olives from the area, from Dry Creek to the Big Horn River to the Town of Greybull itself. Winters admits that when they received initial funding through the state forestry service, the district controller underestimated the size of the project and how it would ultimately grow.
“It started with Wyoming State Fire and their concern with wildfires, and their ability to stop fires from spreading,” he recounted, describing how the thick brush created by Russian olives posed a threat to wildland firefighters and their ability to safely control and suppress wildfires. “They wanted us to put in firebreaks [to help protect towns like Greybull and Basin] and take the Russian olives out, [and] it kind of grew from there. It literally started because they wanted to save lives.
“As we met with the towns and fire marshals, we discussed what everybody wanted, what land owners, what everybody wanted to do with the project. Each land owner got to choose what they wanted to do on their property.”
With half of the funding secured, plans made and a deadline to commit to action on the horizon, Winters applied for additional grants from the Wyoming Natural Resource Trust Fund and a state pesticide program, which were ultimately awarded. In all, Winters estimates that the cost to remove and remediate the areas targeted to-date is roughly $500,000, which he says, “isn’t that bad, at all.”
Using drone technology, BHCWP first scouts and photographs areas to document the spread of the invasive plants and then, in conjunction with the University of Wyoming’s extension offices in Worland and BLM, determines the order in which sites should be targeted as well as how. Depending upon the terrain and obstacles, BHCWP may use either a spray drone, helicopter drops, or utility tasks vehicles (UTVs) to spread the herbicide AquaSweep over the affected area. Following the application of AquaSweep, there is a rest period to ensure the trees die off before Ambient Green, a fire mitigation contractor, begins pruning and masticating the plants.
Winters said that Ambient Green uses mastication to grind “the entire tree down to the stump,” which is then left for monitoring and follow-up treatment in the event of sprouts. He stressed that BHCWP forwent any and all attempts to remove the trees’ root systems due to their ability to regenerate from even a small root fiber: “What we’ve found is that if you pull the root out and leave even a little bit behind, it will re-sprout. We’ve found that if we leave the stump and treat it annually, we have a greater overall impact and use less herbicide overall.”
After three years of monitoring and additional treatments, BHCWP plans to remediate the areas by reintroducing native trees such as the cottonwood, buffalo berry, gooseberry and willows, which were out-competed by the hardy and aggressive Russian olive. They’ve already found that in removing Russian olives, the native sagebrush population has naturally expanded outward. BHCWP hopes that by removing and remediating these areas and continuing to maintain them, both the natural ecosystems and local hydrology are able to begin healing after decades of damage.
“Russian olives can use up to 200 gallons of water per day per plant,” Winters notes. “Talking hydrology, we’re in a desert, so removing those trees means we’re helping everything. There will be water running in places it hasn’t in years.
“The benefits or aesthetics of an invasive species like the Russian olive doesn’t outweigh the risks involved in planting it. There are native species that provide all the same functions — they draw the same songbirds, provide cover and habitat for deer or pheasants — and are beautiful in their own right.”
Winters added that BHCWP is working with Big Horn County Citizens for Economic Development [BHCED] and SBHCD to develop a desktop guide of native plants and planting tips that will be available to the public. And for those with Russian olives on their property that would like them to be removed, Winters has additional resources available.
“We offer the herbicide for sale,” he said, “[but] if we get enough interest in an area and it would pencil out to actually bring in the crews, I’ll write grants and go after funding to make it happen, but it has to be a fairly large area to make it work.” The most recent parcel of land treated by BHCWP was 263 acres. If it’s one or two trees, Winters said that BHCWP can still assist the public by guiding them toward contractors who specialize in tree removal. “We have several who remove them and we can provide that list to anyone who might be interested in having them removed.”
Despite their hard work, Winters knows the reality is that BHCWP will need to continue playing defense against the Russian olive in the months and years to come. The tree has been naturalized, meaning it will almost always exist and endure, despite opposition and best efforts.
“Until Hot Springs and Washakie Counties are treated, we’ll keep getting re-infested,” he predicts, and so BHCWP will continue monitoring and performing removals, maintenance, and remediation as needed.
For now, they will continue removing trees along the Big Horn River and Dry Creek. Looking ahead, they’ve begun planning a strong offensive against the invasive annual grasses that are overtaking the county’s sagelands.
“Once areas convert over from the perennial grasses, it’s hard to get it back,” Winters explained. “That’s going to be worse for livestock and wildlife. We’ll have wildfires every year and the sagebrush won’t be able to recover. It will be bad.”