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.

Updated Boulder County Integrated Weed Management Plan

Boulder County is updating its current weed management plans and policies. Currently, the county is operating with two plans: the Boulder County Noxious Weed Management Plan and the Boulder County Parks & Open Space Weed Management Policies and Procedures. These two documents will be combined into a single Integrated Weed Management Plan.

Plan Approved

The Boulder County Commissioners voted 2-1 on May 23 to adopt the county’s Integrated Weed Management Plan after an extensive planning process and input from the public. The final plan with the amendments agreed upon during the public hearing process will be presented at a future Business Meeting and posted on this webpage once adopted.

The plan applies to private property in unincorporated Boulder County and Boulder County-owned lands. Under the approved plan, herbicides will only be used on less than 2% of county-owned natural land. The plan also prohibits the use of glyphosate (Roundup) and helicopters for aerial application. The county will pilot alternative weed management tools including goat browsing, steam treatments, novel soil amendments, and a volunteer Weed Warrior program.

Draft Integrated Weed Management Plan Version 3.0
Note: this version does not include the changes made by the commissioners.

Previous Draft Plans

Throughout the public engagement phase the county has received a large volume of public input through testimony at public meetings, survey responses, and comments through the online comment form. Much of this input expressed concerns about herbicide use. County staff appreciates the interest, passion, and time dedicated to this process by so many members of the public, and this input was key in shaping the different versions of the plan that were considered.

Additional Resources

  • Integrated Weed Management FAQs: Staff’s responses to frequent comments made throughout the engagement process.
  • List A Weed Species Maps: Maps showing the locations of List A noxious weed species in Boulder County.
  • Relevant Research Studies: A list of scientific studies related to noxious weeds.
  • Story Map: Provides some important planning context and case studies of lands where integrated weed management has already been implemented.
  • Pitkin County Success Story: In four years, a 6-acre expanse transitioned from 26 percent native vegetation and heavily infested with cheatgrass to 81 percent native plants and barely any cheatgrass.

Previous Events

  • May 23, 9 a.m. – Board of County Commissioners
    The commissioners voted 2-1 to approve the Integrated Weed Management plan with changes. Changes will be incorporated to the plan and brought back to commissioners to be signed at a business meeting. Public comments were not accepted at the meeting.
    Watch the Meeting
  • April 16, 3 p.m. – Board of County Commissioners
    Staff presented the Draft Plan Version 3.0. and the commissioners held a public hearing. The commissioners requested additional information to be provided for the May 23 meeting. The hearing adjourned at 8:35 p.m.
    Watch the Meeting
  • March 28 – Parks & Open Space Advisory Committee
    The committee voted 6-2 to recommend that the Board of County Commissioners approval the plan as presented by staff with the following amendments:
    1) Add glyphosate to the list of herbicides no longer used.
    2) Direct staff to create a multi-modal notification system and subscription notification system to notify residents of aerial spraying.
    Watch the Meeting
  • March 12 – Panel Discussion on the State of Science for Integrated Weed Management
    Boulder County held a held a paneled discussion on the state of science for integrated weed management.
    Watch the Webinar
  • Feb. 22 – Parks & Open Space Advisory Committee
    Staff from Jefferson County, Larimer County, and Rocky Mountain National Park presented their agency’s weed management practices. Staff presented a summary of proposed changes to the draft plan. Public comments were accepted at the meeting.
    Watch the Meeting
  • Jan. 25 – Parks & Open Space Advisory Committee
    Numerous public comments were made and the committee heard a presentation on goat grazing for weed management.
    Watch the Meeting
  • Dec. 5 – Parks & Open Space Advisory Committee Study Session
    Study session for in-depth Q&A between committee members and staff.
    Watch the Meeting
  • Oct. 26 – Parks & Open Space Advisory Committee
    Staff provided updates to the management plan.
    Watch the Meeting.
  • Oct. 13 – Weed Management Tour
  • Oct. 11 – Open House and Community Discussion
  • Oct. 2 – Draft plan, Story Map, and Survey Released
  • Sept. 28 – Parks & Open Space Advisory Committee
    Staff provided updates on the management plan.
    Watch the Meeting
  • Aug. 24 – Parks & Open Space Advisory Committee
    Lisa Blecker, Colorado State University Administrator, Pesticide Regulatory Education Program, gave a presentation on the Pesticide Labeling, Safety, and Approval Process.
    Watch the Presentation
  • Aug. 22 – Weed Management Tour
  • July 27 – Parks & Open Space Advisory Committee Site Visit
  • July 25 – Weed Management Tour
  • June 22 – Parks & Open Space Advisory Committee
    Scott Nissen, Professor Emeritus at Colorado State University, gave a presentation on the Behavior of Cheatgrass.
    Watch the Presentation

Written Public Comments

Written public comments were accepted Feb. 15 through May 23. Comments were reviewed by staff, Parks & Open Space Advisory Committee members, and the Board of County Commissioners.

View submitted comments

Community Survey

A community survey was open from Oct. 2–19, 2023. The survey received 1,076 responses, including 555 open-ended responses. Questions were designed to solicit thoughts on weeds as threat to ecosystem health and their contribution to wild fire risk, and opinions about alternative weed management programs, ranging from no herbicide use to herbicides as the primary tool. Respondents were asked to refer to the initial draft plan and companion story map for more information and examples.
Community Survey Results

Herbicide and Roadside Mowing

Parks & Open Space will not be conducting any aerial herbicide applications until the Integrated Weed Management Plan has been finalized.

Daily Planned Herbicide Applications

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

View Past Activity

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

Daily Planned Roadside Mowing

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

View Past Activity

Management Practices

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

  • 34,000 acres of land designated as natural areas.
  • 120 miles of trail.
  • 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.


Cheatgrass (downy brome) reduces native plant diversity, impacting resources for wildlife including native pollinators and increasing the risk for negative outcomes during wildfires.

On June 22, Scott Nissen, Professor Emeritus at Colorado State University, gave a presentation to the Boulder County Parks & Open Space Advisory Committee on the behavior of cheatgrass and the associated impacts to open space and natural areas.

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