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Invasive Plants & Weed Management on Open Space
Open space

Invasive Plants & Weed Management on Open Space

Parks & Open Space is responsible for weed management on open space areas, certain agricultural leased lands, and designated county maintained roads.

Parks & Open Space will not be conducting any aerial herbicide applications until the weed management policy has been updated and a decision on whether to resume applications has been made.

Staff is working on updating policies and procedures and the process will provide opportunities for public input this fall. The Boulder County Commissioners are the final decision makers on adopting policy changes. Opportunities for online and in-person input on this important land management topic will be announced here and on social media. Sign up for news alerts

Herbicide & Roadside Mowing

Herbicide & Roadside Mowing


Management Practices


Report Weeds

Daily Planned Herbicide Applications

Herbicides currently applied to open space areas that are open to the public are reported below.

View Past Activity

Daily Planned Roadside Mowing

Mowing currently being performed along county maintained roads are reported below.

View Past Activity

Additional Information

Please call the weeds hotline at 303-441-3940 for daily updates.

If you have any concerns or would like to learn more about the herbicides being applied, please contact the National Pesticide Information Center.


The invasive plant and weed management program is responsible for weed control on:

  • 25,000 acres of land designated as natural areas.
  • 7,000 acres of agricultural leased land that serves as wildlife habitat.
  • 685 miles of county maintained road right-of-way.


The Boulder County Noxious Weed Management Plan requires eradication of all List A species, as mandated by the state, and containment and suppression measures for 13 of the List B species identified as significantly troublesome in Boulder County. Of the 18 List A species, 10 are currently known to exist in Colorado, and nine of those are known to exist in Boulder County.

Staff utilizes an integrated pest management approach to controlling weeds that include mowing, hand pulling, insect bio-control, cultural control (tilling weeds and planting desirable vegetation), and herbicide application. Herbicides are only used in targeted areas.

When controlling noxious weeds on open space properties, staff are careful to use the least damaging and most effective weed control strategies available. Staff always consider the local ecology to maintain and support the rich ecosystems of open space lands.


  • Minimize the occurrence of weeds and associated negative impacts on native plant communities, agricultural lands, and public corridors.
  • Utilize an integrated weed management approach in order to prevent the introduction of new invasive plant species, eradicate isolated or limited populations, and contain and manage weed species that are well established within the county.
  • Stay current with weed management research and innovative management techniques that may increase effectiveness of weed control and/or decrease environmental impacts.
  • Promote education and awareness of new and potential invasive weed species.

What You Can Do

  • Identification and do not plant them in your garden. If they already grow in your garden, remove them.
  • Report a Concern on private property.
  • Parks, Environment, Gardening & Agriculture Volunteer Opportunities
  • Educate friends and neighbors who have these plants growing on their properties. Their plants will likely spread to your property.
  • Minimize spread of weeds on open space by staying on the trails, feeding horses weed free hay, and cleaning weed seeds from your hiking boots or bicycle tires before recreating on open space property.
  • Attend a Weed Identification and Management Workshop through CSU Extension.

Report Weeds

On Private Property

The Community Planning & Permitting Department is responsible for enforcing compliance with noxious weed regulations in unincorporated Boulder County.

Report a Concern

On Open Space

If you see noxious weeds on open space, please let us know.

Report Weeds on Open Space

Contact Us

Parks & Open Space