Prairie Pothole Region

I recently heard about someone driving across eastern North Dakota and wondering when North Dakota got all its lakes. We are in a wet spell, and there are a few lakes in eastern North Dakota, but the vast majority of those bodies of water are prairie potholes.

At the end of the last ice age, as the glacier retreated northward, they left the landscape with variable amounts of glacial till as well as large blocks of ice. When all that ice melted away, the landscape was pocked with small closed depressions filled with water. Here in North Dakota, these potholes or cattail sloughs generally lie between the Red River Valley and the Missouri River.

These wetlands are just a part of what is known as the Prairie Pothole Region, which is a band of native prairie on glaciated landscapes that runs from northern Iowa then northwestward through south western Minnesota, eastern portions of North and South Dakota, and the southern portions of Manitoba, Saskatchewan, and southeast Alberta. Although not a particularly large geographic area, it is gargantuan in terms of importance to waterfowl and shorebirds. The region supports something like one-half of the North American migratory waterfowl.

These potholes are typically shallow basins with emergent vegetation such as cattails and bulrushes. They support myriads of invertebrates which are important food items for waterfowl and other migratory birds. The wetlands also support a wide variety of animals ranging from marsh wrens to crayfish to mink. They are also important to the hydrology of the region.

Because most of these potholes have no inlet or outlet, they receive the bulk of their water from the spring snow melt. Many dry out by autumn. These temporary wetlands are particularly important to waterfowl.

More than half of the wetlands in the Prairie Pothole Region have been drained, most for conversion to farmland. As most every North Dakotan knows, wetland drainage has been a hot and controversial issue, in part because the remaining wetlands in the Prairie Pothole Region are arguably the most important area for waterfowl in North America.

Chuck Lura

Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Minot State University-Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.