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. 

Noxious Weed Advisory Board

Municipalities such as Castle Rock may have one of their boards or commissions, such as our Parks and Recreation Commission, meet as a Weed Advisory Board. The Parks and Recreation Commission was presented with this option 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 PlanFinal Management Plan cover

Town staff, led by the Parks and Recreation Department, has drafted a Noxious Weed Management Plan. This plan includes an overview of the Colorado Noxious Weed Act, management options / approaches, implementation of the plan, public education, ongoing program evaluation and species identification and management guide. Since weed management codes apply to both public and private lands, the Town solicited and incorporated public input on the draft plan. The final management plan was presented and approved by the Weed Advisory Board in its final format on May 19, 2021 and by Town Council on June 1, 2021. This plan was approved by Town Council on second reading on July 6, 2021. 

View (PDF) a copy of the final 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 were presented and approved by Town Council on first reading on June 1, 2021. Council approved the updates to the Municipal Code on second reading on July 6, 2021.

View a copy of Ordinance 2021-012 (PDF)


The Colorado Weed Management Association website features helpful introductory videos providing education, identification and management tips for select weed species found in our area.

Douglas County will be hosting a free Noxious Weed and Wildfire Prevention Workshop. Join land, vegetation and wildfire experts to learn how to identify and eradicate invasive noxious plants during this free in-person and online workshop. Additional information about this workshop can be found at

Noxious Weed and Wildfire Prevention Workshop

April 16, 2022
8 a.m.-noon
PS Miller Building, Hearing Room
100 Third St.

Download the event flyer

Report a Concern

The Colorado Noxious Weed Act is applicable to all private and public properties, therefore It is the duty of every owner of land within the Town to manage all weeds growing on their property in accordance with the Town’s Noxious Weed Management Plan. For any other weeds not designated under the Noxious Weed Management Plan, every owner of land shall cut, or cause to be cut, all weeds growing thereon, in such a manner that all cut portions are reduced in length to six (6) inches or less, with the following exception: that owners of parcels of ground within the corporate limits which contain more than five (5) acres in one (1) contiguous parcel shall be required to cut weeds only from those portions of said parcel which are within one hundred (100) feet of a structure or paved street. In the event that all weeds are not reduced to a length of six (6) inches or less, then it shall be required that all cut weeds be removed from the property to some place where refuse is ordinarily disposed.

If you notice noxious weeds within the Town of Castle Rock, you may submit a report online to The Town Code Enforcement Division. Go to to report an issue.