An 242-acre area on the east side of Big Spirit Lake, containing a large marsh feeding into the lake, plus restored prairie uplands north of the marsh and shoreline trees along the lake.

From Iowa Highway 9, on the east side of the bridge over East Okoboji Lake, take Co. Highway M-56 winding north about 4 miles to the Hales Slough entrance road sign. Turn west and follow entrance road to parking area between lake and marsh. Also, continue about 1/4 mi. north on M-56 to a roadside parking area along the restored grasslands.

Marshy habitat dominated by emergent vegetation hosts many kinds of nesting and migratory waterfowl, American Bitterns. Restored prairie uplands offer good habitat for many grassland species. This is a public hunting area.