Since it is part of the river system, there is no closed season here, with the best place to fish right now near Blackhawk Island at the lake's east end entry point.

Some walleyes spawn in Koshkonong, with many others venturing upstream into little tributaries like the Bark River. Extensive stocking over the past decade from a hatchery facility on Bark River has resulted in multiple year-classes of walleyes, with a number of fish from initial year-classes in the upper-20-inch range.

Tailwaters of the Jefferson Dam above the lake, the Indianford Dam just downstream, and at both the Monterey Dam in Janesville and Beloit Dam are popular places for 'eye chasers to congregate this time of year. Walleyes in Rock River spawn just before walleyes in the Lower Wisconsin River, usually within five days of April 1 each year.

Targeting that slack water/fast water interface is the key to success, with fish often holding in pools no larger than a living room. Drain tubes, creek entries and similar places are good places to probe, as are ambush points like the small pool downstream from the high school in Jefferson across the river from the big rapids.

A meat-and-potatoes approach of the basic jighead and minnow or Lindy Rig with a minnow typically works best here, with gold jigs no heavier than 1/8-ounce.

Contacts: Riverfront Resort, Blackhawk Island, (920) 563-2757; U-Catch Em Bait, Janesville, (608) 754-7976; Dick's Tackle & Bait, Beloit, (608) 362-8712

On any given day it is possible to count over 100 boats from any given point above Voyageur Park, just below the dam, from ice-out until about April 20. A fish refuge is established between the dam and power lines just downstream, with wardens writing many tickets each spring to those who would get a couple inches too close.

Why would any angler subject himself to "bumper boats" in this extreme sense? Because walleyes inhabit that neck of river between the Highway 172 bridge and the dam by the gazillions at mid-April every year, with many fish over 10 pounds. Relatively few of these fish are legally hooked during daylight hours. Those who can orient their watercraft to cast a little slack-water channel and don't mind pulling an "all-nighter" will eventually be rewarded with a whopper.

This fish won't come cheap, however. Just about everybody throws fire-tiger ThunderSticks or jointed No. 13 Rapalas, removing the front treble hook after they've lost a dozen lures or so to the rocks. Last spring I went "crankbait fishing" with my extendable Stowmaster landing net after the sun came up and the bite slacked off. Thirty-three crankbaits worth $5 a pop isn't bad wages for a couple hours' probing near the dam.

Contacts: Bob's Bait, 1-800-447-2312, www.BobsBaitandTackle.net; guide Karl Plog, (920) 336-9860.

Lure selection is the same - fire-tiger ThunderSticks and Rapalas - once fish begin to move inland from staging points at the mouth of Green Bay. This migration will be quick, lasting no more than a day or two. Hit it right like I did in the spring of 2002 and you'll experience a natural high. Imagine catching 22 walleyes in just a couple hours, all weighing from 5 to 11 pounds, while dozens of walleyes continue to bump into your waders on their way upstream!

Last year I was perhaps a day late, catching only one legal fish over 10 pounds, which was released along with at least a dozen more that were inadvertently snagged. Although the bag limit is only one fish daily, foul-hooking is definitely a problem here with no easy answer. Barbless hooks only? Certainly worth considering.

Contacts: Michigan DNR Web site, www.fishline.com; Marinette Inn, 1-800-468-1939; AmericInn, (906) 863-8699.

Walleyes staged in Lake Winnebago - our state's premier walleye factory - get the urge to move many miles upstream to Fremont and beyond just about the same time walleyes are going great guns on the Fox, which is sometime between April 10 and April 20.

Like other rivers, the major upstream push on the Wolf happens at night. But unlike the Fox and to a lesser extent the Menominee, the gauntlet these fish have to run is more linear than wide.

A 5-year-old can cast across this river up around New London. But the Wolf here is surprising deep. A good plan is to set up in an ambush point where the slack water meets the fast water - like an entry point to a marsh - and employ a Wolf River rig or similar presentation that allows the fish to come to you rather than actively casting to them.

The upstream run only lasts a couple days at best. But when fish are done, they take a more leisurely slide back downstream a little higher up in the water column. Those marks halfway to the bottom on your electronics are walleyes until proven otherwise.

Contacts: Critter's Sports, (920) 582-0471; Double B Guide Service, (920) 836-2377.

Target areas near the buoys just in from the main lake in a trolling presentation with crankbaits and spinner-rig crawler harnesses. Keep a jig rod rigged and ready to probe obvious breaks, and pitch either light jigs and plastic tails or small crankbaits when probing around the riffles upstream below the first dam.

May on the St. Croix typically means high and roily water as the Midwest tries to shake winter runoff down the Mississippi. A popular local spot is the Kinnikinnic Narrows between Prescott and Afton, Minn., with the swing bridge at Hudson also worth a look.

The Web site www.InDepthAngling.com is your smartest first stop before planning a trip to either of these rivers when May rolls around. This site keeps a close watch on river levels and other variables, with a river's mood the primary key to fish activity.