Flowages and River Runs

John Kolbeck, guide and avid crappie angler from Wisconsin, likes to fish flowages, which are basically small hill-land or flatland reservoirs that usually have small dams and substantial current. Often dams are located at both ends, and flow is especially strong in spring, when snowmelt and rain send runoff through these narrow riverine environments.

Flowage crappies in northern habitats seek backwaters and large bays well away from the main flow of the river during winter. Crappies seem reluctant to leave these backwater areas until the surface is completely ice-free. When the ice is gone, with surface temperatures approaching 50°F, they begin moving out to current breaks in the main channel of a flowage.

“After ice-out, crappies move behind islands in the lower, downstream end of the flowage,” Kolbeck says. “Around the end of April, as water temperatures climb into the mid-40°F range, they begin migrating upstream to the dam, where some stay into early summer. They move against the current by using a trail of classic breaks along the way, such as eddies, fallen trees, and stumpfields. They hold there for a short time in May, on their way to and from the dam. But the largest prespawn concentrations occur behind the dam, where they’re full of eggs when we catch ’em.”

Like all other species of fish that migrate into current, crappies always take the path of least resistance. Steelhead, salmon, smallmouth bass, walleyes—all fish faced with a major upstream migration—utilize inside bends, woodcover, concrete abutments, flood plains, undercut banks, deep holes, and the side of the river farthest from the main channel during upstream migrations. Where possible, they string these current breaks and reduced-current areas together to form a trail, one they use year after year when the time comes to move. Of all these species, however, crappies are positioned farthest from the main current. While a trout may use the outside edges of branches dangling in the main flow, and smallmouths the heavier branches in the midsection of a fallen tree, crappies often huddle right where the trunk intersects the bank. And it should be remembered when chasing migrating river fish that friction with the bank and stream bottom reduces flow. Current is often slowest near bottom, the reason river crappies are often found there.

“Most crappies hold below the dam until water temperatures reach almost 60°F,” Kolbeck continues. “Several weeks later, some are still holding below the dam. Throughout May, the uneven bottom areas below dams hold the highest concentrations of crappies, which tend to lie right on bottom, out of the current behind structure. Once the water warms to about 60°F, the current is typically reduced from what it was a few weeks earlier, and crappies may no longer avoid the main flow, which is not that strong in most flowages to begin with. Some may position in front of a bar—on the upstream side—in 1 to 2 feet of water. In fact, we catch smallmouth bass in the same areas. This pattern holds into the low-60°F range. In years when crappies don’t spawn due to extreme conditions or a series of severe cold fronts, they can be caught well into June, still stacked by the dam,” Kolbeck says.