Mapping Montana Wetlands

Montana’s statewide Wetland and Riparian Mapping Framework provides a digital map layer of wetlands, deepwater habitats and riparian areas across the state. The layer is part of the  Montana Spatial Data Infrastructure , co-stewarded by the University of Montana, the Montana State Library, and the Montana Department of Environmental Quality. 

The following story map introduces standard wetland mapping nomenclature used in Montana’s statewide wetland and riparian mapping layer and offers brief descriptions of habitat and function for each wetland type present in Montana. 

There is no universally accepted definition for wetlands, with established definitions varying based on their intended use. The term generally refers to land supporting vegetation and soils that reflect permanent or periodic saturation or inundation. The most widely recognized definitions refer to three characteristics of wetlands: hydrology, hydric soils and hydrophytic vegetation. The National Wetlands Inventory (NWI) and Montana Statewide Wetland and Riparian Mapping Layer follow the US Fish and Wildlife Service (FWS) definition below:

"Wetlands are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water... Wetlands must have one or more of the following three attributes: (1) at least periodically, the land supports primarily hydrophytes; (2) the substrate is predominantly undrained hydric soil; and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season of each year" [1].

For more information on NWI Wetland Mapping, follow this  link .

Wetland classification systems are used to group wetlands based on features such as vegetation, water source, function, or landscape position. A standardized classification system provides consistent units to inform use, management, and planning decisions.

Montana's Statewide Wetland and Riparian Mapping Framework adapts the standard NWI wetland classification system to map form using a system of alphanumeric codes. The codes are structured hierarchically, from System and Subsystem at the broadest levels to Classes, Subclasses, and Water Regime at finer scales [2].

Scroll down to see examples of characteristic Montana wetlands and their corresponding NWI wetland codes.

Wetland codes: PEM1A, PEM1C, PEM1F 

Prairie potholes occur in Montana within intermontane glaciated valleys and in the northeastern great plains [4, 5].

Wetland codes: R3UBH, R3USA, R3USC, Rp1FO, Rp1SS, Rp1EM

A free-flowing, fifth order tributary of the Columbia River, The Blackfoot River spans 212 river-kilometers (132 river-miles) from its headwaters along the continental divide near Rogers Pass, Montana to the confluence with the Clark Fork River just east of Missoula, Montana [10].

Wetland Codes: R2UBH, R2USA, R2USC, Rp1FO, Rp1SS, Rp1EM

The Milk River and the Powder River are two of Montana's characteristic lower perennial rivers.

Wetland codes: PEM1Bb, PEM1Eb, PEM1Fb, PSS1Bb, PSS1Eb, PSS1Fb

Beaver influenced wetlands occur adjacent to ponds, small lakes, streams, and rivers throughout the state of Montana [12].

Wetland codes: L1UBH, L2ABG

Bowman Lake is the third largest lake in Glacier National Park with a surface area of 7 square kilometers (2.7 square miles) and a depth of 77 meters (253 feet).

Wetland codes: PEM1C, PEM1F

Emergent marshes are widespread throughout Montana from foothill to upper montane elevations [16].

Wetland codes: PEM1D, PEM1B, PSS1D, PSS1B 

Rocky mountain subalpine-montane fens occur sporadically throughout western Montana.

Click individual features below to read habitat and function descriptions for each wetland type in Montana. For more information on the Statewide Wetland and Riparian Mapping Framework, visit our website.