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La Plata County, CO Invasive Plant Rules: Prohibited Species (2026)

Significant Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Governing section
Land Use Code Sec. 70-17, subsection III.B
Named trees and shrubs
Ash, cottonwood, tamarisk, Siberian elm, Russian olive
Weed lists
State noxious weed lists, county plan, board designations
Cottonwood exception
Side or rear borders with open space or natural areas
Import ban
Sec. 58-36 bars importing or cultivating noxious weeds
Plan renewal
Board approves weed management plan every three years or sooner

Summary

In unincorporated La Plata County, Colorado, Section 70-17.III.B prohibits planting state and county noxious weeds plus ash, cottonwood, tamarisk, Siberian elm and Russian olive. Cottonwood has one narrow exception along open space borders, and Section 58-36 bars importing or cultivating noxious weeds.

These county ordinances apply to unincorporated areas of La Plata County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

B. The installation, planting, or placement of the following are prohibited on any property: 1. Plants listed on the Colorado Department of Agriculture Noxious Weed lists; 2. Plants listed in the La Plata County Weed Management and Enforcement Plan referenced in Chapter 58 of the county’s code and adopted and updated by the board pursuant to section 58-35; 3. Plants designated by the board pursuant to sections 58-33 and 58-34 of the county’s code; 4. Ash (Fraxinus, all species); 5. Cottonwood (all species, including Populus deltoides, P. fremontii, and P. nigra), unless being used to continue the native appearance along the borders of side or rear lot or parcel lines with open space or natural areas; 6. Tamarisk (Tamarix, all species); 7. Siberian elm (Ulmus); and 8. Russian olive (Elaeagnus angustifolia, all cultivars).

Full Breakdown

Section 70-17.III.B bars a fixed list of plants from being installed, planted or placed on any property under the section in unincorporated La Plata County, Colorado. The list has eight items. Items 1 through 3 track lists that change: plants on the Colorado Department of Agriculture Noxious Weed lists, plants listed in the La Plata County Weed Management and Enforcement Plan referenced in Chapter 58 and adopted and updated by the Board of County Commissioners under section 58-35, and plants the board designates under sections 58-33 and 58-34. Items 4 through 8 name species outright: ash (Fraxinus, all species), cottonwood (all species, including Populus deltoides, P. fremontii, and P. nigra), tamarisk (Tamarix, all species), Siberian elm (Ulmus) and Russian olive (Elaeagnus angustifolia, all cultivars).

Cottonwood carries one printed exception: it is allowed when used to continue the native appearance along the borders of side or rear lot or parcel lines with open space or natural areas. Subsection III.A separately prohibits invasive species as part of a new development or redevelopment project.

Chapter 58 backs the list. Section 58-33 lets the board elevate a state B list or C list noxious weed found in the county to the A or B list, and section 58-34 lets it designate additional undesirable plants after a public hearing with 30 days prior notice to the public. Section 58-36 prohibits importing seeds, propagative plant parts or live plants and cultivating any noxious weed within the county, and says a person doing so is fully prosecutable under C.R.S. § 35-5.5-104.5. Under section 58-35 the weed office maintains the management plan and the priority weed list and makes them available to the general public, and the plan must be renewed and approved by the board not less than once every three years. A landscaping plan must include a legend giving the species, quantity, size and description of existing and proposed plants, so a listed species shows up on review.

Violations & Fines

Planting a listed species is a violation of the Land Use Code under Section 80-3. The director, code enforcement officer or building official can issue a notice to correct violation by certified mail, and an uncorrected violation can become a violation determination appealable to the Board of County Commissioners within ten (10) days. Section 58-36 makes importing or cultivating a noxious weed prosecutable under C.R.S. § 35-5.5-104.5, and Section 80-6 lets penalties run for each day.

Frequently Asked Questions

Which trees are banned from landscaping in unincorporated La Plata County?
Section 70-17.III.B prohibits ash (Fraxinus, all species), cottonwood (all species, including Populus deltoides, P. fremontii and P. nigra), tamarisk (Tamarix, all species), Siberian elm (Ulmus) and Russian olive (Elaeagnus angustifolia, all cultivars). Cottonwood has one exception for continuing the native appearance along side or rear borders with open space.
Where do I find the list of prohibited weeds?
Three lists apply: the Colorado Department of Agriculture Noxious Weed lists, the La Plata County Weed Management and Enforcement Plan, and any plants the Board of County Commissioners designates under sections 58-33 and 58-34. Under section 58-35 the weed office maintains the plan and the priority weed list and makes them available to the public.
Can the county add plants to the list?
Yes. Section 58-33 lets the board elevate a state B or C list noxious weed to the A or B list after consulting the advisory commission. Section 58-34 lets it designate additional undesirable plants for eradication or management after a public hearing with 30 days prior notice to the public.
Is it illegal to bring noxious weed seed into the county?
Section 58-36 prohibits importing seeds, propagative plant parts or live plants and cultivating any noxious weed within the county. A person who does so is fully prosecutable under C.R.S. § 35-5.5-104.5. That is a separate hook from the landscaping prohibition in Section 70-17.III.B.

Sources & Official References

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