Protecting the High Country in Southwestern Colorado

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The rugged San Juan Mountains in southwestern Colorado are well known for their soaring peaks, stunning vistas, and hiking, hunting and wildlife viewing opportunities. The area is also a place where invasion of non-native plants threaten wildlife, watershed, and scenic values. 

Ron Mabry, Ouray County Weed Manager, and Rod Cook, La Plata County Weed Manager, agree that weeds like oxeye daisy and yellow toadflax have the potential to change the San Juan Mountains forever. Mabry and Cook joined forces in 2007 to encourage other county, state and federal partners to work together as a team to control oxeye daisy and other invasive plants. Their efforts led to the formation of a large-scale cooperative weed management area in southwest Colorado. 

The San Juan Mountains Cooperative Weed Management Area (CWMA) officially organized in 2014, joining nine counties and multiple agency partners in an effort to manage invasive plants within 5.5 million acres. The purpose of the CWMA is to work cooperatively to inventory, monitor, control, and prevent the spread of noxious/invasive weeds across jurisdictional boundaries.

“The CWMA is a living, growing and changing entity with multiple partners committed to controlling invasive plants in the beautiful San Juan’s,” Mabry says. Both Cook and Mabry agree that by working together the group increased their opportunity to secure grants and can more efficiently put funds on-the-ground. 

Oxeye daisy (Leucanthemum vulgare) was first reported in the San Juan Mountains in about 1995 along Highway 550. Caye Geer, a cabin owner on Electra Lake, said the weed was seeded on the highway right-of-way as part of a wildflower mix. 

“I noticed the daisy in the mid-90s and thought how pretty it was. So I dug some up and planted it near our cabin, and others did the same,” explains Geer. “It didn’t take long for us to realize that oxeye daisy was very invasive and spread quickly. I also noticed that the plant was having an impact on native orchids and wildflowers.” 

Geer and others in the area formed a committee to tackle oxeye daisy and other invasive plants near Electra Lake. Although their local effort continues to be effective, oxeye daisy has spread to infest about 3,000 acres in the Animas River watershed. Movement by vehicles along infested roadsides, contaminated seed, and intentional planting as an ornamental continue to be the main avenues for spreading oxeye daisy to non-infested areas.

In the high mountain environment of southwestern Colorado, oxeye daisy has several bloom cycles and produces seed into late fall. This long bloom period and high seed viability increases the plant’s ability to spread quickly, especially on disturbed sites. Ben Bain, GIS specialist for La Plata County, measured the rate of spread in some areas at about 50 percent per year. [See Oxeye Daisy Biology and Management on page 6]. 

“Our focus in 2015 was to remove oxeye daisy along roadsides and newly established infestations,” explains Cook. “This will reduce spread and help protect areas that are mostly weed-free.” Herbicide applications were also made to small isolated infestations of other invasive plants such as Canada thistle (Cirsium arvense), musk thistle (Carduus nutans), and yellow toadflax (Linaria vulgaris). 

The CWMA successfully treated 109 miles of secondary non-paved roads, 24 miles of Highway 550, and about 28 miles of Narrow Gauge Railroad from Rockwood to Silverton with Milestone® herbicide at 5 fluid ounces per acre (fl oz/A). “So far the results the season of treatment look very promising,” says Cook. 

A unique aspect of the San Juan CWMA is training armed forces veterans to inventory and control invasive plants (See Cook explains, “One of the biggest issues in this area is that there aren’t enough commercial applicators to meet our needs. Our grant included funding to train military veterans in a new career as professional commercial applicators.” The two veterans trained and hired by the CWMA in 2015 spent the summer working on oxeye daisy infestations in the high country of the San Juan Mountains. The U.S. Forest Service and Upper San Juan Weed and Pest District donated trucks, and Rod Cook donated spray equipment to the project.


Public education and outreach is an important component of the CWMA. The LaPlata Conservation District (LPCD) has been an active partner in the CWMA, coordinating grant funds and helping educate the public about invasive plants. 

“The most important role of our organization is to educate the community about the impact of noxious weeds,” says Tom Hartnett, LPCD president. “A lot of people think plants like oxeye daisy are pretty and dig them up to plant in their lawns. It is important for them to understand the impact of these weeds on elk, other wildlife, and native plants; and how quickly they spread.”

Another partner the CWMA hopes to involve is the Mountain Studies Institute (MSI) in Silverton, Colorado. MSI is an independent, not-for-profit, mountain research and education center concentrating on environmental issues facing the San Juan Mountains. “It would be great to have research data on the impact of oxeye daisy on our high-elevation native plants and wildlife,” says Cook.

Funding for the oxeye daisy project included a $40,000 grant from the Colorado Department of Agriculture. The La Plata Conservation district also received additional funds for noxious weed control. They include a $25,000 grant to cost share weed control projects with landowners in the district, and a $14,000 grant to address local weed issues bordering public lands. Cook and others in the CWMA agree that grant funds are important, but maintaining or increasing county funding is critical for long-term support of sustainable invasive plant management projects. 

Partnerships formed through the CWMA are critical to managing the large project area. “We appreciate the commitment from La Plata County for facilitating and managing crews, writing grants and mapping weed infestations,” says Mabry. “It takes a team effort to make this work.” Early detection and treatment of oxeye daisy and other invading plants, and long-term sustainable funding are critical to protecting native plant communities in the San Juan Mountains “We can never get back the diversity of native plants and wildlife if we don’t protect these areas from invasive plants now,” says Cook. 

Partners and Cooperators

  • County Weed Districts (La Plata, Ouray, San Juan, San Miguel, Archuleta, Hinsdale, Dolores, Gunnison, and Montezuma Counties)

  • Conservation Districts (Shavano, San Miguel and La Plata)

  • Rio Grande Resource Conservation and Development Council

  • Colorado Department of Agriculture

  • Colorado Department of Transportation

  • Colorado Parks & Wildlife

  • Colorado Native Plant Society

  • US Forest Service

  • Bureau of Land Management

  • Natural Resource Conservation Service

  • Mesa Verde National Park

  • Glacier Club

  • Purgatory Metro District

  • Durango and Silverton Narrow Gauge Railroad

  • Numerous private individuals

Published April 2016; trademark updated June 2019.

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