The state's hottest walleye water might be Upper Red in the northwest part of the state, where limits have been commonplace since ice left the lake May 15.

So many walleyes have been caught it's possible the summer angling take from the big lake will reach 100,000 — the same number of walleyes harvested from Upper Red last winter.

Anglers will have even more to cheer about Saturday, when the Department of Natural Resources changes the lake's protected walleye slot from 17-26 inches, to 20-26 inches. The lake's walleye limit will remain four, with one allowed over 26 inches.

Upper Red's great fishing can be traced to the cool days and cold nights that have prevailed this spring and early summer. Both have helped keep the lake's water temperature relatively low. As a result, walleyes have stayed fairly congregated and shallow.

Usually by this time of June, these fish have dispersed more widely into the lake.

"Also, we've had a lot of east and southeast winds, which have allowed anglers to get onto the water to fish,'' said Henry Drewes, DNR regional fisheries supervisor in Bemidji.

Strong west and northwest winds often keep Upper Red anglers off the lake, because most access the lake from its eastern shoreline.

Upper Red's walleye harvest estimate, based on DNR creel surveys, was 27,000 through Memorial Day.

"That's our fifth-highest May harvest in the eight years since we reopened the lake to fishing,'' Drewes said. "It would have been a lot higher, but this year we lost most of opening weekend fishing to the ice.''

The walleye catch rate in May on Upper Red was a torrid 2.23 per hour per angler. The harvest rate was .74 walleye per hour.

"That's twice what Mille Lacs is on a good year,'' Drewes said, "and twice what Lake of the Woods is in a good year.''

Enough walleyes in the 17-20 inch range exist in Upper Red to withstand harvest in those sizes, Drewes said.

"The fish will disperse throughout the lake, which helps protect them, and fishing pressure also falls off some in June,'' Drewes said. "If we had the 20-26 inch protected slot in effect during the first few weeks of the season, they could take a disproportionate hit. But not now.''

Dennis Anderson • danderson@startribune.com