Lowland and flatland impoundments are common in the northern and central Midwest. The deepest water is typically 18 to 40 feet near the dam. The rest of the reservoir is often one huge 10- to 15-foot flat divided by a meandering creek or river channel. It could be flooded wood, farm, or pasture land. The only structure is the channel and a few nondescript humps. Main attractions include the riprap by the dam, scattered rock piles usually left by farmers, and perhaps a flooded woodlot that may be no more than a stump field.

Although walleyes seldom grow huge, a 10 pounder is possible, and overlooked 3- to 4-pound fish are fairly typical. The prime spawning habitat can be upstream in the main river, especially in reservoirs not cleared of timber. Much depends on the river, however. If it has ample current, is relatively free of silt, and offers optimum spawning substrate (pea gravel), some walleyes spawn there. If so, they stage near the river mouth in 6 to 10 feet of water at the beginning of prespawn. Here crankbaits, blades, and jigs with plastic grubs or shad bodies excel.

Walleyes may migrate quite a distance upstream in some of these reservoirs. Gary Towns of the Michigan Department of Natural Resources works on several productive flatland impoundments. “Even though the reservoirs are mostly cleared of timber, walleyes here are river spawners,” he says. “Fish migrate up to the next dam, and where no dam exists, we have no idea how far they go, but it’s a ways. These are May fisheries. Postspawn is prime time in the upper third and into the middle of the reservoir.”

In flatland impoundments with slow, muddy feeder rivers, most walleyes spawn on riprap by the dam, but the genetics of fish stocked in the lake may also produce lake spawners. These fish stage in relatively deep water adjacent to the dam and river channel. The best presentation usually is vertical jigging with minnows.

Spawning takes place in March in most flowages, when water temperatures are between 42°F and 48°F. Immediately after spawning, walleyes at either end of the reservoir begin migrating toward the midsections. These movements are a microcosm of what happens in every other reservoir type. Fish may not move as far, but they definitely move.

Walleyes in the upstream and downstream ends migrate into the midsection of the reservoir, often quickly (within two weeks), depending on weather. Productive patterns include trolling the flats (use in-line boards and cranks or spinner harnesses with crawlers) to find scattered fish, but generally it’s best to focus on three key spots: (1) rock piles or hard-bottomed humps and points in the main lake; (2) outside bends in the main river channel; and (3) rock or gravel bars, piles, or humps in otherwise muddy bays. A good rule is to work any rocky areas.

Drift and troll with bait rigs to find fish quickly in channel bends. Anchor or work from the bow, casting jigs or jigging spoons to rock piles, points, and humps. Some of these reservoirs, such as the flowages in Wisconsin, can be quite long. During postspawn, look for intervening logjams, humps, rock piles, and channel bends along the main channel between the same two key spawning sites—upriver and by the dam.

As with all other reservoir types, paying close attention to trends in weather and water conditions produces results. If water temperatures are between 42°F and 50°F for any length of time, fish will be spawning. Knowing when this occurs is a major key. The more time that elapses after the temperature reaches 42°F to 50°F, the more distance between walleyes and their spawning habitat.

Migrations back to summer habitat are predictable, so you can follow them from one point or flat to the next. If cold fronts and high water intervene, walleye migration slows considerably. High water warms slowly and cold fronts may stop migration for several days, even a week. Plan accordingly and begin your search closer to spawning habitat.