IMPOUNDMENT CLASSIFICATION

We use six broad categories to classify reservoirs: canyon, plateau, highland, hill-land, flatland, and lowland (or wetland). These classes are based on regional and geological aspects of North America’s wildly various landforms. Both natural and manmade characteristics determine what class an impoundment fits into. There are, of course, many exceptions. Some small reservoirs and “flowages” are hard to classify. Also, some reservoirs have portions characteristic of different classes, just as rivers and lakes do.

Lowland Impoundments

Lowland impoundments are the shallowest category of reservoir, sometimes with a maximum depth of fewer than 15 feet, usually found in the old creek channel. A small dam blocks a small river, causing a wetland to fill and spread greatly due to the low, flat terrain. In Wisconsin, lowland impoundments called flowages provide multispecies fisheries, as do lowland impoundments on bayous in Louisiana.

Lowland impoundments feature vast flats with cover provided by the flooded timber and thick vegetation that sometimes grows in rich soils. Some such waters have many small, low islands and may contain old pond dams in the basin, offering a bit of structure. Current is minimal and fishing patterns are typically similar to those in natural lakes.

Flatland Impoundments

Many of the nation’s most notable crappie fisheries fall into the flatland classification. Waters like Barkley Lake, Kentucky-Tennessee; Lake Seminole on the Georgia-Florida border; and Santee-Cooper in South Carolina offer a broad, shallow basin extending from a main river channel that meanders through farmland and low hills. Several broad arms define former tributary creeks that may run only during the rainy season.

Because of the shallow, fertile basin, aquatic plants may thrive in clear impoundments, sometimes covering 50 percent or even more of the surface area of the reservoir. Weed-fishing patterns predominate in these waters, though flooded timber, brushy banks, and stumps also offer cover for crappies, particularly in flatland impoundments that are murky and thus have little plant growth. River channel ledges in the 12- to 20-foot range also hold crappies. Bass are abundant, too, and other species including white bass, hybrid stripers, and catfish are also common. These older reservoirs continue to offer excellent fishing.