Noxious Weeds

Noxious weeds are non-native plants that displace or out-compete native plants for soil moisture and degrade natural habitat. Many noxious weeds are undesirable to cattle and wildlife, and can even be toxic. It is important to manage noxious weeds in our area through identification, prevention and control of infestations.  

Noxious weeds can be introduced through seeding, as ornamental escapes or can establish in disturbed areas (roadsides, overgrazed pastures, construction areas) as well as riparian corridors and wetlands. To control or prevent infestations and educate landowners, the state-wide Colorado Noxious Weed Act (35-5.5 CRS) (PDF) was established to identify a noxious weed list and prioritized management goals. The state’s noxious weeds are grouped into three different lists - A, B and C. This helps determine whether it should be eradicated, contained or controlled.

View a current list (PDF) of noxious weeds

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Noxious Weed Act

In an effort to control or prevent noxious weed infestations, the State adopted the Colorado Noxious Weed Act as included in Title 35 of the Colorado Revised Statutes. The law requires all Colorado residents, including local land managers, control noxious weeds using integrated methods to manage those noxious weeds. 

Find additional information on the statewide Noxious Weed Program administered by the Colorado Department of Agriculture.

According to the Colorado Noxious Weed Act, municipalities have certain responsibilities that include:

  • Establishment of a local advisory board
  • Adoption and administration of a noxious weed management plan
  • Treat public lands, including rights-of-way, to impede the spread of noxious weeds

Current Town Practices

The Town’s Parks Division actively manages noxious weeds found in parks and open spaces within Castle Rock boundaries. Staff uses an integrated process consisting of mowing, spraying, pulling, utilization of native landscaping and biological controls. In the past, the Town has also asked volunteers to assist with weed management, and has also released weevils in Town parks and open spaces to feed on knapweed. 

Next steps in the noxious weed plan

Noxious Weed Advisory Board

Municipalities such as Castle Rock, may have one of their boards or commissions, such as our Parks & Recreation Commission, meet as a Weed Advisory Board. The Parks and Recreation Commission was presented with this option at the January monthly meeting and Town Council provided approval by resolution on Feb. 2, 2021 (PDF) to revise the existing commission duties to include the formation of an advisory board.

Responsibilities of the Weed Advisory Board include:

  1. Develop recommended integrated weed management criteria and plans for managing priority noxious weeds 
  2. Declare noxious weeds and any state noxious weeds designated by rule to be subject to integrated management
  3. Prepare and recommend to Town Council a weed management plan
  4. Review the management plan at regular intervals but at a minimum once every three years

Noxious Weed Management PlanNoxious Weed Management Plan draft front cover

Town staff, led by the Parks & Recreation Department, has drafted a Noxious Weed Management Plan for future consideration by a Weed Advisory Board and Town Council. This plan will include an overview of the Colorado Noxious Weed Act, management options / approaches, implementation of the plan, public education and ongoing program evaluation. 

View (PDF) a copy of the draft Noxious Weed Management Plan

Town Municipal Code Update

According to the Noxious Weed Act, municipal code provisions must address noxious weed management specifically, however, many municipal codes are limited to a height ordinance which serves a fire prevention purpose rather than a noxious weed control function. Currently, section 8.12 of the Town’s Municipal Code limits growth of weed height to 12 inches or less. It is the responsibility of the property owner to manage weed height on their respective property. At this time, the Municipal Code does not specifically address noxious weeds located on properties within Town boundaries, nor does it specifically reference the Colorado Noxious Weed Act. Proposed code changes regarding the Colorado Noxious Weed Act will be presented to Town Council for consideration later this year.

Public Feedback

Since the noxious weed management plan applies not only to Town property, but also private property, the Noxious Weed Advisory Board collected online feedback. During the public comment period, four comments were submitted by residents and included two suggestions for improving the plan. These suggestions included the addition of photos to help identify certain weeds in Castle Rock and establishing a reporting mechanism specific to noxious weeds through the Town’s existing “Report-a-Concern” option. Additionally, the public comments identified a Town-owned site that has weeds requiring attention – Town staff is currently evaluating this site and following up accordingly. View a full summary of the public comments (XLSX).


Collected feedback will be presented at the April 21 Parks and Recreation Commission meeting and a proposed Noxious Weed Management Plan will be finalized for presentation at the May 4 Town Council meeting.


Mark your calendars to join staff from Douglas County virtually on Saturday, April 24, from 9 a.m. to noon for the livestreamed Noxious Weed Education Workshop. Watch for participation details to be posted on the Douglas County website.