Hill-Land Impoundments

Hill-land impoundments provide the classic reservoir shape, with many small fingers branching from a main basin that surrounds a major river channel. These impoundments are deeper than flatland impoundments but not as wide, because hills on either side of the river constrict them. Creek arms are narrower and deeper, with extensive submerged timber, though this form of cover has been declining over the many decades since most of these reservoirs were built.

Water color ranges from fairly clear with a greenish tinge to stained. The color may vary seasonally, with spring rains making the water murky and summer plant growth fostering clear water in creek arms. The upper end of the reservoir tends to be murkier where the main river enters, with silt gradually falling out as water approaches the deep basin near the dam. Crappies often undertake seasonal shifts in location, particularly during the Prespawn and Postspawn Periods, and prior to the Coldwater Period.

Highland Impoundments

Dams on highland impoundments usually are constructed in steep, narrow ravines. This category of reservoir is therefore narrow but very deep, where high bluff walls border long, narrow, deep-creek channels. The basin itself is also narrow and extends from higher elevations down to the dam. The deep basin offers few or no islands, but tributary creek arms may include islands and underwater humps. Most crappie fishing in spring occurs in the upper end of creek arms as fish move from deep structure to spawning areas.

Clear water with little cover can be a challenge for anglers. Crappies may live in available shallow cover or hold in water deeper than most anglers are accustomed to fish. Preyfish are not abundant, which limits crappie numbers. Dawn, twilight, and night-fishing are popular on these waters, because crappies roam shallower and seem to feed more actively in low-light conditions.

Canyon Impoundments

Huge concrete dams across steep, narrow canyons form canyon impoundments, the dominant type in the Southwest and West. These waters are the most capacious and deepest reservoirs, often over 200 feet. They’re also ultraclear, a result of the sand and rock that form the basin. These substrates yield little plant life, so cover is in the form of sparse stick-ups, boulders, and sheer canyon walls with occasional rock slides. Canyon impoundments are narrow and very long, with long tributary arms.

These oligotrophic impoundments typically feature a deep, oxygenated hypolimnion that supports stocked rainbow trout. Warmwater species like crappies usually inhabit shallow bays and tributary arms, but also may roam the open water to feed.