Weed management in Larimer County is a major function of the Land Stewardship Program under the Department of Natural Resources. The Weed Management Program is responsible for weed management on all county-owned properties, (including parks and open spaces) and, county road rights-of-way. The Weed Management Program assists county residents through education and outreach programs, site visits, recommendations, cost-share and is obligated to carry out enforcement procedures stipulated in the County Weed Management Plan. The program is partially funded through the Larimer County Weed District, which encompasses the eastern one fourth of Larimer County. Activities conducted outside the Weed District are supported through an enterprise program that obtains funds from contracted weed management work with private landowners, federal, state, and local agencies and from state and federal grants.

Weed management can be a challenge in Larimer County with extreme variations in topography and climatic conditions. Subdividing of farms and ranches across the county has led to large scale disturbances of many mountain, shrubland, and plains areas leaving sites open to weed invasion. Introduction of exotic weed species occurs with a steady influx of people from all parts of the country transporting livestock, animal feed, off-road vehicles and other vectors for weed seed movement.

Larimer County weed management procedures follow an integrated management approach utilizing herbicide application, mowing, hand pulling, insect bio-control, and cultural control. It must be recognized that not every tool can be successfully used in every situation and there will be site-specific needs that will require flexibility to achieve most effective weed control. Management decisions are based on results derived from University and USDA-Agriculture Research Service field trials. Please consult the Weed Management Reference Guide for Larimer County for more specific information.

The Larimer County Weed Management Program will strive to minimize the occurrence of weeds and associated negative impacts on native plant communities, agricultural lands and public corridors in Larimer County. In doing so, staff will strive to establish and maintain relationships within the community based on best land stewardship practices. We will achieve this by collaborative research and discourse, making ourselves and our resources accessible to the public and continuing education amongst the general public as well as land stewardship professionals.

Utilizing an integrated weed management approach, the program will make every effort to prevent introduction of new invasive plant species, eradicate isolated or limited populations, and contain and manage weed species that are well established within the county. In doing so the program will:

  • Assist Larimer County residents in managing noxious weeds through site visits, management recommendations and cost-share programs.
  • Promote education and awareness of the presence of new and potential invasive weed species in Larimer County.
  • Stay current with weed management research and innovative management techniques that may increase effectiveness of weed control and/or decrease environmental impacts.
  • Assist Larimer County Agricultural Extension Agents in disseminating information pertaining to identification, impact and management of weeds on agricultural and residential lands.
  • Cooperate with County Resource Specialists for weed management needs relating to restoration projects and agricultural production.
  • Map distributions of various invasive weed species in the county by way of GPS technology, and monitor the spread or decline of infestations over time.
  • Assist in development of weed management plans with federal, state, and local government agencies, and municipalities within Larimer County.
  • Collaborate with federal, state, and local agencies within Larimer County, and statewide as necessary, on weed management projects, field research, and education & outreach programs.
  • Work in concert with the Colorado Department of Agriculture and comply with the Colorado Noxious Weed Act.
  • Implement the Larimer County Noxious Weed Management Plan on county-owned properties and rights-of-way, and enforce it as needed on private lands in unincorporated Larimer County.

The Colorado Noxious Weed Act states that noxious weed management is the responsibility of local governing agencies: incorporated municipalities, counties, and lands owned by state and federal agencies. The Act states that the board of county commissioners of each county in the state shall adopt a noxious weed management plan for all the unincorporated lands within the county. The Larimer County Noxious Weed Management Plan was approved by the Board of County Commissioners on March 6, 2008. Enforcement procedures stipulated by the management plan are the responsibility of the Land Stewardship Manager under the County's Department of Natural Resources. Larimer County, in cooperation with the Colorado Department of Agriculture, Colorado State University Cooperative Extension, and other agencies, actively promotes compliance of the Noxious Weed Act. The County will enforce with the Act's provisions, on noncompliant landowners.

  • The Larimer County Noxious Weed Management Plan was adopted in 2008 to conform to the Colorado State Noxious Weed Act, which was most recently revised on May 3, 2004.
  • The basic change that occurred in the 2004 revision of the State Weed Act was the categorization of noxious weed species into 3 lists: A, B, and C.
    • List A species require mandatory eradication by local governing agencies.
    • List B species are mandated for eradication in some parts of the state, and recommended for suppression or containment in other areas depending on distribution and densities around the state.
    • List C species are widespread and well established.
  • The state also has introduced a Watch List which are species listed to educate and encourage identification and reporting.
  • The Larimer County Noxious Weed Management Plan requires eradication of all List A species and infestations of certain List B species identified as regionally scarce by the state, and containment and suppression measures for List B species identified as significantly troublesome in Larimer County. County outreach programs will emphasize identification and management of 16 List B species but reserves the right to enforce on any state-listed noxious weed if the infestation size and density deems it necessary.
  • The County Weed Management Plan cannot be enforced on private or public property without first applying the same measures to any land or rights-of-way owned or administered by the County that are adjacent to such properties.

The Colorado Noxious Weed Act mandates that every local governing agency manage noxious weeds within their jurisdiction (Colorado Noxious Weed Act). It is the obligation of the Weed District to conduct enforcement procedures in order to prevent the spread of invasive species and deter detrimental effects to the environment and economy of Larimer County. The Weed District will make every effort to assist landowners in compliance prior to carrying out enforcement action. The weeds that will be enforced upon are on the Noxious Weed list for Larimer County and Weeds Mandated for Eradication by the State of Colorado. Enforcement procedures are as follows:

  • When a noxious weed problem is brought to the attention of the Weed District a notice to enforce will be sent by certified mail.
  • A courtesy notice is sent prior to the enforcement notice, at the discretion of the district office, if time allows for subsequent effective management.
  • County weed management personnel will be available for site visits and management recommendations free of charge.
  • Upon receiving the enforcement notice, the land owner has ten days to:
    • Manage the weed in the prescribed manner.
    • Present a weed management plan, or
    • Request a waiver
  • After 10 days, Weed District staff can enter upon the property of non-compliant landowners and conduct appropriate management action (mowing, spraying, etc.)