Aquatic Noxious Weed Program
Invasive weeds threaten the ecological integrity of aquatic environments in Montana. Eurasian watermilfoil, curly-leaf pondweed and flowering rush have become established in the state, and there is a high risk of invasion by other non-native aquatic plants.
These plants are highly competitive and affect fisheries, native plants, waterworks, power generation and irrigation. Increased aquatic plant biomass also impacts water quality and recreational resources.
Invasive aquatic plants are transported by hitching a ride on animals, watercraft and recreational vehicles, as well as scuba, fishing and hunting equipment.
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How can you help?
Before launching and before leaving:
- Inspect boat, trailer, and equipment.
- Remove aquatic plants, animals, and mud.
- Drain water from boat, motor, bilge, live wells, and bait containers.
- Spray/rinse boats and recreational equipment with high pressure, and/or water above 140 degrees, or let recreational equipment dry for at least five days.
- Clean waders and boots.
- Drain water from bait containers.
Hunting & Other Outdoor Activity
- Inspect equipment, decoy lines, anchors, waders and pets.
- Remove weeds/seeds by washing equipment and brushing or cleaning animals.
Montana Aquatic Noxious Weeds
Other Aquatic Plants of Concern in Montana
Guide to Montana's Freshwater Aquatic Plants
Click on the items below to download the complete guide or parts, meant to help with identification of Montana's freshwater aquatic plants.
- Complete Guide (5.21 MB, PDF)
- Table of Contents, Acknowledgements & Introduction (345 KB, PDF)
- Plant-Like Algae (285 KB, PDF)
- Floating Leaved, Rooted Plants (1.01 MB, PDF)
- Submerged Plants (2.44 MB, PDF)
- Free-Floating Plants (285 KB, PDF)
- Shoreline Plants (1.23 MB, PDF)
- Glossary, Index & References (273 KB, PDF)
Montana Pollutant Discharge Elimination System
State requirements regarding discharge permits have changed. Please visit the Montana Department of Environmental Quality website for information.
Aquatic Pesticide License
Application of aquatic herbicides in Montana requires a special-use license. The Montana Department of Agriculture oversees the licensing and training of aquatic pesticide applicators. Applicators who intend to treat waters with state restricted-use aquatic herbicides (xylene or acrolein) must attend a special aquatic training session and pass an Aquatic Pest Control Exam for initial certification. Training and testing is offered once a year by the Department.
The Department conducts aquatic herbicide applicator recertification training sessions periodically. These are listed with other applicator training opportunities on the Pesticides page.
About Pesticide Licensing
Biological Weed Control
Biological weed control is a long-term management technique that involves releasing natural enemies to control non-native species. Typically, insects are imported from continents where the noxious weeds originated. Insect predators are carefully tested to be sure they only attack a specific weed and are safe to release in North America.
The most successful method of weed control is an Integrated Pest Management (IPM) approach. IPM consists of using herbicides, biological weed control agents, grazing, mowing and other mechanical methods.
Acquiring Biological Control Insects
In Montana, several biological control agents have been successfully used to reduce infestations of noxious weeds such as leafy spurge and spotted knapweed. County weed coordinators can provide information on implementing biological control methods, and acquiring insects. See the links below for more information.
Other Contacts for Biological Weed Control
Noxious Weed Mapping
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