This natural depression is located in the Des Moines Lobe landform region and includes the “thumb” of Iowa most recently covered by glaciers (10-12,000 years ago). The many large oak trees around the lake’s edge often stood in shallow water. To the early settlers it looked as though the ground had sunk after the trees began to grow, and so they named this area Sunken Grove. The Bur Oak Savanna remnants found on the island today date to 1870 when all the old growth oak, hackberry, and cottonwood were harvested.

Pothole Birding

A drive-through road and overlook offer great bird viewing throughout the seasons but especially during spring and fall migration. Song birds can be found along the wetland's shoreline and prairie edge habitat, as well as among the timber along the drive-in road. Waterfowl, Great Blue Herons, American Bittern and other wetland birds are prevalent throughout the marshes.

Location Description

This 250 acre lake/wetland is a great place to visit any time of the year. Listen for frogs calling in the spring.

Driving Directions and other Information

• Sunken Grove is located 2 miles west of Fonda on Hwy 7 and 2 miles north on 110th Ave.
• Shimon Marsh is located 1 mile west of Fonda on Hwy 7 and 2 miles north on 120th Ave.
• Sunken Grove Wildlife Area - 110th Avenue
• GPS location N 42 48.722 W 094 26.698
• Sunken Grove Island - 110th Avenue
• GPS location N 42 48.398 W 094 26.862
• Shimon Marsh - 120th Ave. and 600th Street
• GPS location N 42 37.543 W 09453.690
• 35 acre island managed by Pocahontas County Conservation Board
• 55 acre Voss Prairie Wetland - Pocahontas County Conservation Board
• 250 acre lake, 1,027 acres restored prairie and wetlands- Iowa DNR.
• Prairie and Woodland Plants, Canoeing/Kayaking, Hunting, Picnicing, Wildlife Viewing

Educational Activity:

To be added

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Take a short visit to Sunken Grove/Shimon Marsh Wetland Complex via the video below!