Understanding Eradication 

Colorado's Noxious Weed List

Colorado has a prioritized weed list based on the abundance and distribution within the state.  Based on where a species falls on the list and what part of the county a property is in, owners must eradicate List A.  The must eradicate, contain, or suppress List B species.  List C species are recommended for control

List A

Weeds that have limited sites and populations within the state.  These weeds must be eliminated whenever found.

Visit the List A page for identification and control information. The List A species known to be in Jeffco include: 

  • Arundo
  • Cypress spurge
  • Dyer's woad
  • Hairy willowherb
  • Knotweed
  • Myrtle spurge
  • Orange hawkweed
  • Purple loosestrife
  • Yellow flag iris
  • Yellowstar thistle

List B - Eradication

Weeds identified as having varying populations throughout the state. Eradication zones may be established in areas where the weed is uncommon and complete elimination is required. 

Please visit the List B page for identification and control information.

List B - Countywide Eradication

These List B noxious weeds are limited in their distribution and number of infestations within Jeffco. They are required to be eradicated whenever they are found.

  • Absinth wormwood
  • Black henbane
  • Bull thistle
  • Common tansy
  • Dame's rocket
  • Moth mullein
  • Oxeye daisy
  • Perennial pepperweed
  • Plumeless thistle
  • Russian knapweed
  • Salt cedar (aka Tamarisk)

List B - Eradication and Containment Zones

These List B noxious weeds are required to be eradicated in parts of the county and controlled in all other parts of the county.  The maps show the eradication zones within Jeffco.

List B - Control

These List B noxious weeds that must be controlled and suppressed.  These species are found throughout much of Jeffco.

  • Canada thistle
  • Dalmatian toadflax
  • Eurasian watermilfoil
  • Jointed goatgrass
  • Musk thistle
  • Scotch thistle
  • Yellow toadflax