Ninety-two miles without a dam
Below the Prairie du Sac dam the Wisconsin River runs free to the Mississippi at Prairie du Chien, 92 miles by the Lower Wisconsin State Riverway Board's count, which it calls one of the longest free-flowing stretches left in the Midwest. This page is about that river, not the impounded Wisconsin above the dam, the Dells or Lake Wisconsin. Black Earth Angling Co., which guides it out of the Sauk City area with jet-powered jon boats, describes a wide river that rarely exceeds 10 feet and is often under 4, with a sand bottom that shifts constantly and 98 species of fish. The Riverway Board cites an older DNR and University of Wisconsin collection of 84 species from 20 families. Either way it is a Mississippi River fish list in a wadeable river, which is why Kyle Zempel's clients see paddlefish, sturgeon and quillbacks between smallmouth.
The gauge this page uses, USGS 05407000 at Muscoda, is about halfway down the Riverway and has recorded since 1913. The hub's other Wisconsin River gauges at Wisconsin Dells, Wisconsin Rapids, Rothschild and Merrill are on the dammed river upstream and describe different water.
November to April: walleye and sauger under the dam
The DNR's Travel Wisconsin write-up for the tailwater is specific enough to fish from. From late November through April the walleye and sauger action concentrates below the Prairie du Sac dam, where a significant movement of fish comes upriver from late fall through spring; most are Lower Wisconsin residents, with a few from the Mississippi. Just below the dam and the brush island is a 22-foot hole that holds pre-spawn walleye, fished by working small jigs tipped with minnows around its edges, and the standard rig is a 1/8 to 1/4 ounce jig with a 2 to 4 inch fathead. When the crowd is thick at the dam, the same page says to drop downstream to current breaks, slack water and shoreline wood next to deep water. A white bass spawning run follows in early April and May, and by late spring the walleye and sauger spread onto sand flats, drop-offs and wood downriver, sauger deeper than walleye.
The DNR has monitored the Prairie du Sac tailwater every year since 1986, and its creel report notes the Lower Wisconsin walleye population is sustained entirely by natural reproduction. The rule below the dam is a walleye minimum of 18 inches and a sauger or hybrid minimum of 15, and in Crawford County, the last miles to the Mississippi, the county listing adds a daily bag of three in total.
June: the Crash
Smallmouth are supposed to be fish of the rocks, and there are almost none here. Tom Davis's Hatch Magazine piece on a June day with Zempel lays out why the river works anyway: crayfish are rare on the sand, but emerald shiners are staggeringly abundant, and the Lower Wisconsin's smallmouth have learned to hunt them in packs, blowing up on schools along a piece of shoreline, under the branches of a downed tree or where a sandbar drops off into current. Zempel named it the Crash, and the fishing is a minnow imitation, a Crease Fly or a Dahlberg Diver, dropped into the froth. Davis's day included northern pike charging off the bank, an 18-inch white bass from the day before, and Zempel's note that the muskies here mostly show up trying to eat a hooked smallmouth.
Black Earth Angling's seasonal summary: spring is pre- and post-spawn smallmouth, post-spawn pike and the white bass run; summer is the Crash; fall is pike and musky and often the biggest bass of the year. Prime dates on the shop's smallmouth calendar are gone by the end of April.
August: sandbars, stable current, topwater
August is the month the river drops and the sandbars rise, and the shop builds a multi-day trip around it for the most consistent topwater window of the season. The Riverway Board's rules for the bars matter if you stay out: sandbar camping is free and camping on the shorelands is not permitted, private land is private, and because water levels change daily with rain anywhere in the watershed, pick a bar with high ground. Its safety line is worth repeating: if you are not prepared to swim it, do not canoe it or wade it, and wear a life preserver. Wet wading is in sandals; the shop's advice is footwear the sand rinses out of, or bare feet.
Bank fishing is allowed throughout the Riverway on state-owned land, and the board asks anglers to be sure they are on it. Launches the DNR names on the upper end include the Sauk City launch, the VFW Park launch and the Mazomanie landing.
The Lower Wisconsin rulebook: bass, catfish, sturgeon
The 2026-2027 hook and line guide puts the Lower Wisconsin in the southern bass zone: largemouth and smallmouth may be kept from May 2, 2026 through March 7, 2027, five in combination at 14 inches, and are catch and release the rest of the year. Hook and line fishing for other species is open all year on the river, with the season extending up tributaries to the first highway bridge. Catfish are closed from the Prairie du Sac dam down to the Highway 12 bridge except from May 2 through November 30, with a bag of 10, and muskellunge upstream of the Highway 12 bridge must be 50 inches.
Two sturgeon rules are new for 2026. Lake sturgeon on the Wisconsin River from the Merrill Flowage dam to the Mississippi are catch and release only from June 6, 2026 through March 7, 2027. Shovelnose sturgeon on the Lower Wisconsin below the Prairie du Sac dam have a season from July 4, 2026 through March 7, 2027 with a bag of 3 and no length limit, the only inland water in the state where they may be kept. Motor trolling is permitted countywide in Sauk, Iowa, Richland, Grant and Crawford counties with three lines per person.
Reading Muscoda
Nobody in the shops publishes a cfs range for this river, so the 4,000 to 9,000 cfs band on this page is the USGS record at Muscoda in the wading months: monthly means of about 6,350 cfs in January, 10,900 in March, 16,900 in April, 12,300 in May, 11,100 in June, 7,700 in July, 6,200 in August, 7,400 in September and 7,500 in October. Below about 9,000 the bars are out and a jet boat is the only motor that makes sense; above it the river the Riverway Board warns about, deceptively placid and rising overnight, is the one you are on. The dam releases at Prairie du Sac and rain anywhere upstream reach Muscoda with a lag, so compare the gauge to yesterday's reading before you choose a bar to sleep on.