What’s Different in Flathead County?
- Local priority weeds based on real infestations
- Additional species managed at the county level
- Landowner responsibilities and compliance requirements
Flathead County uses the Montana State Noxious Weed List, but also identifies additional species and priorities specific to this region.
Top Noxious Weeds in Flathead County
Based on local monitoring and management data, the following weeds are the most widespread or impactful in Flathead County.
Most Common & Widespread
- Canada Thistle
- Spotted Knapweed
- Oxeye Daisy
- Orange Hawkweed
These species account for the majority of infestations and should be prioritized for control.
Locally Significant Weeds
- Tansy Ragwort (high priority)
- Common Tansy
- Leafy Spurge
- Houndstongue
- St. Johnswort
- Sulfur Cinquefoil
Early Detection — Report Immediately
- Eurasian Watermilfoil
- Flowering Rush
- Saltcedar
These species are rare in Flathead County but pose serious risks if they spread. Contact the Weed Department if identified.
Featured Priority: Tansy Ragwort
- High priority for eradication
- Actively monitored and mapped
- Managed in coordination with state, federal, and private partners
Flathead County uses a “search and destroy” approach to prevent the spread of this species.
Additional Weeds Managed by Flathead County
Priority 2A (County-Specific)
- Baby’s Breath
- Russian Thistle
- Tumble Mustard
- White Campion
- Absinth Wormwood
- Noble Yarrow
- Kochia
Unwanted Species
- Creeping Bellflower
- Scentless Chamomile
Where Weeds Spread Most
- Roadways and rights-of-way
- Trails and recreation areas
- Gravel pits and disturbed soil
- Construction and development sites
Disturbed ground and high-traffic areas are the most common entry points for new infestations.
Landowner Responsibilities
- Prevent weeds from spreading or going to seed
- Implement a weed management plan
- Respond to notices of infestation
Managing noxious weeds is required under Montana law.
Compliance & Enforcement
- Property inspections may occur
- Written notices may be issued
- Weed management plans may be required
If no action is taken, the County may treat the infestation and bill the landowner.
Weed Management Support
- Weed identification assistance
- Management planning guidance
- Educational materials
- Sprayer rentals
Report a Noxious Weed
If you suspect a noxious weed infestation, contact the Flathead County Weed Department:
Phone: (406) 758-2161
Email:
Statewide Information
For full weed classifications and statewide listings, visit the Montana State-Declared Noxious Weeds page.