The genetic history of most reservoir crappies extends back to a time before the water was impounded and they were living in a river, where extensive migrations were required to find suitable habitat during each of the four seasons. In flatland reservoirs, the need to travel persists, and crappies may move miles between spawning grounds and summer haunts after the water warms into the low to mid-70°F range. During this migration phase, which can last days or weeks, crappies are often tough to locate and tougher to consistently pattern.

Even in summer, flatland reservoirs produce a breed of strawberry bass that amaze, amuse, and baffle most anglers. Call ’em papermouths, speckled bass, or calicos, if you prefer (someone once said that crappies have more aliases than a roomful of criminals). Point is, even crafty old locals who spend copious hours of free time chasing flatland crappies can come up blank during summer.

Ned Kehde, former archivist for the University of Kansas and a longtime In-Fisherman contributor, studies the stupefying ways of flatland crappies year ’round. In summer, he admits to spending most of his time hunting them on mudflats. “Most fishermen focus on channel edges,” he says. “Lots of crappies cruise these drop-offs into 25 or 30 feet of water along the river channel during summer, but I’m finding larger fish on brushpiles in 14 to 20 feet of water in the middle of expansive, uneventful mudflats most years.

“Most crappies in the flatland reservoirs of Kansas evacuate coves sometime in June,” Kehde says. “The water in the shallows becomes too warm. Though flatland reservoirs can have maximum depths ranging from 45 to 55 feet, the best flats are in mid-depth areas.”

The best brushpiles are frequently the ones placed in the middle of nowhere, a long distance from any appreciable structure or depth change. Crappies also find a brushpile balanced along the edge of a minor drop of only 2 to 4 feet very appealing as well—as long as it’s in the middle of an otherwise homogeneous mudflat. But some of the best spots coincide with shoreline points, where the widely spaced contours of a gently sloping mudflat bend out toward the main river channel.

Sometimes we’re lucky enough to stumble onto an old brushpile out there, but (in states where it’s legal) it’s best to place your own, made with hardwood and cinder blocks, buckets of brush filled with cement, or just a pile of limbs bundled together and weighted down with rocks. (Be certain to mark each one with your GPS, while also triangulating its location with shoreline objects or highlights.) “The best brushpiles are made of willow,” Kehde notes, “though cedar or hedge lasts longer. I don’t know why, but crappies seem to prefer willow.”

Crappies often suspend vertically near the tops of brushpiles, but they might also be found suspended anywhere within 20 feet or so of the pile. When they’re up high in clear, calm water, boats spook ’em. Under those conditions, Kehde likes to put a marker near a brushpile and anchor a short cast away. He then pitches jig/plastic combos and swims jigs horizontally over and around the cover. But most days and in most conditions, Kehde prefers to jig vertically with 1/16- to 1/8-ounce jigs tipped with 2- to 21⁄2-inch tubes. “During summer, your presentation should be vertical about 80 percent of the time and horizontal about 20 percent,” he adds.

Rising water in a flatland reservoir sends crappies shallow. Conversely, drawdown forces them to secondary drop-offs. In either case, the mudflat pattern can dissipate, so it tends to follow a stable-condition model. “Still, the mudflat pattern in 14- to 20-foot depths always ends up being the most consistent for bigger crappies over the course of the season,” Kehde affirms. “But, if the reservoir is less than 15 years old, crappies can remain somewhat channel-bound, as if they don’t trust things not to revert back to the way they were before the dam was built. But the real reason crappies in newer reservoirs continue to relate to river and creek channels is the fact that fewer brushpiles have been planted on the flats. Also, as a reservoir ages, the less distinct its channels become.”

Most of the mudflat patterns Kehde talks about take place on the main lake away from the river channel. The most obvious summer patterns in flatland reservoirs involve crappies around brushpiles along the top lip of river and creek channels; but as Kehde insists, these are also the most commonly exploited patterns. Other patterns that persist through summer on flatland reservoirs include areas 10 to 20 feet deep, usually on brushpiles, logs, or submerged timber, in the backs of bays or the very back end of creek arms. These patterns hold until water temperatures at the surface drop below 60°F in fall.

Flowages: A type of reservoir similar to a flatland impoundment is the flowage, a riverine environment found mostly in Wisconsin, Minnesota, and some other upper midwestern states. A flowage is generally narrower than a flatland reservoir, with more current and created with a smaller dam. They’re often located in rolling country with hills and valleys. Flowages are often filled with cover in the form of flooded and fallen timber, cribs, and submerged brush. Flowages also can be ideal for the recruitment of riverine chubs and shiners. The combination of cover and an apparently limitless food source in a flowage can produce an excellent trophy crappie fishery.

Flowages can be tough to pattern during the Postspawn Period, because the fish scatter and have almost unlimited cover options. Crappies settle into summer patterns late, usually sometime in August. In the latitudes where flowages exist, the nights are already beginning to cool, and water temperatures are slowly backing down from summer highs. Crappies begin to school more tightly at this time, in and around the densest cover available on 10- to 15-foot flats adjacent to the river channel. As the nights begin to cool the water in late August, these schools begin to group even more tightly and start to move deeper.

The best spots in flowages from late August through September are often the deepest holes in the old river channel—the same places crappies frequently inhabit during winter. These holes occur in bend areas, and typically range from 18 to 28 feet in depth. When highly active during late summer, crappies may spread back up onto the flat during feeding forays, into the densest cover available in depths of 10 to 15 feet. They may group heavily where combinations of cover come together—for instance, logs mixed with brushpiles and boulders, with a few stumps thrown in for good measure.

It can be difficult to tell what the cover is composed of when using only sonar. An underwater camera can reduce the amount of time spent looking for key spots. It’s typical to fish 10 to 20 areas filled with dense cover before catching a single crappie, but the next spot could hide the mother lode concentrated in a small area of mixed cover. Once discovered, these spots ordinarily remain exemplary for the remainder of the season, and for many seasons to come during late summer and early fall.

Like their cousins in flatland reservoirs, crappies in flowages are most active during periods of stable weather with intermediate barometric pressure, and suspend in or near the tops of the branches of fallen timber and brushpiles. They may retreat into deeper holes and hug bottom after a cold front. But, as late summer gives way to fall, mild cold fronts may actually turn crappies on and precipitate a hot bite.