Why Map Weeds?

Mapping is an essential component to any successful vegetation management project. Like a doctor doing a diagnosis before prescribing treatment, mapping weeds prior to control and revegetation efforts is critical to knowing what kinds of noxious weeds you have, where, and in what abundance. Mapping will not only help you plan your weed control strategy, but allow you to evaluate the effectiveness of your control methods. Mapping also helps land managers track the spread of noxious weeds and measure changes in weed abundance. Weed maps allow land owners and land managers to see the big picture of a noxious weed infestation. Whether the big picture is on the scale of a backyard, a valley, a county, or a state, knowing the full extent of what you are dealing with is the key to being effective in your weed control efforts.

Weed Mapping 101

There are numerous techniques for mapping noxious weed infestations. What technique you use depends on the size of the area you are managing, the amount of time you have for mapping, equipment availability and your comfort level with GPS and computer mapping techniques. If you are a small acreage landowner (under 5 acres), simply using a blank piece of paper and hand drawing your property lines and weed infestations may suffice. However, if you own a larger parcel, a farm or ranch, or are responsible for many acres of public land, you will probably need to use more advanced GPS mapping techniques.

The Missoula County Weed District utilizes the Montana Noxious Weed Survey and Mapping System, which identifies weed infestations through the species, the size of the infestation, and the percent of the ground covered by a species (coverclass). Extension Bulletin 148: Mapping Noxious Weeds in Montana and MONTGUIDE : Montana Noxious Weed Survey and Mapping System are good introductions to this mapping system. Copies of both publications are available at the Missoula County Weed District office.

If you are interested in helping us expand our inventory of known noxious weed infestations in Missoula County, look at our weed maps and use the Weed Observation Form to report any infestations we don't have in our system.

More advanced training in weed mapping is obtainable through the Missoula County Weed District. We offer mapping courses and are available for consultation on your mapping project. We have a number of Garmin and Trimble GPS units that can be checked out to use on your mapping project and we can assist you in processing and interpreting the data you collect.

Contact Jed if you are interested in mapping training or want to check out a GPS unit.

GPS Loaner Program

The Missoula County Weed District has two Garmin etrex GPS units available for the public to use on weed mapping projects. The Garmin etrex is a recreational grade GPS that is easy to operate and efficient for collecting weed points on small to medium scale weed mapping projects. We also have Trimble GeoExplorer3 GPS units available on a more limited basis for large scale weed mapping projects. We will train you on the operation of the GPS and basic weed mapping techniques, download and process your weed data when you return the GPS unit and provide you with a map of your weeds. Contact This email address is being protected from spambots. You need JavaScript enabled to view it., 258-4220,  if you want to take advantage of this opportunity.

Weed Maps
These maps show the presence or absence of noxious weeds in Missoula County by section. If you know of a weed infestation in a part of the county that is not reflected in these maps, please report it so we can update our system.

Dalmatian Toadflax
Leafy Spurge
Spotted Knapweed
Sulfur Cinquefoil


Montana Digital Atlas at the Montana Natural Resource Information System (NRIS)

Montana Natural Resource Information System: Maps and GIS data for the State of Montana.

Missoula County Property Information System

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