MILWAUKEE COUNTY

Nature Conservancy protects wetland water supply

Don Behm

Milwaukee Journal Sentinel

Debbie Maurer (left) of Lake County Forest Preserves and Stephanie Judge of The Nature Conservancy look over a 58-acre property The Nature Conservancy purchased in Kenosha County, just west of the Chiwaukee Prairie natural area.

A conservation group long active in preserving the uncommon cluster of prairie ridges and wetland swales along the Lake Michigan coast in Kenosha County is extending its reach inland to protect sources of water that help sustain rare native plants in the shoreland swales.

The Nature Conservancy recently purchased a 58.6-acre property east of state Highway 32 and north of the state line to prevent development and loss of this vital water-holding open space, said Nick Miller, the conservancy's science director in Wisconsin. Restoration of former wetlands that had been drained for agriculture will boost its rain absorbing capacity, he said.

The property is west of Chiwaukee Prairie, a state natural area encompassing the beach ridge and swale corridor that bumps up against a bluff in the Village of Pleasant Prairie. A rail line between the City of Kenosha and Chicago sits on the edge of the bluff, which marks the farthest inland advance of the lake thousands of years ago.

Development of much of the upland area immediately west of the rail line with houses, businesses, streets and parking lots would reduce the volume of groundwater flowing toward the lake and threaten to dry up globally significant wetlands within the beach swales, Miller said.

A study by the Southeastern Wisconsin Regional Planning Commission and U.S. Geological Survey found that groundwater levels in the wetlands could drop 2 to 4 feet depending on the extent of development west of the rail line, Miller said.

Rain and snow falling on open space west of Chiwaukee Prairie seeps into the soil and becomes groundwater that flows east before resurfacing in the shallow swales, said John Skalbeck, a professor of geosciences at the University of Wisconsin-Parkside. He participated in the USGS study.

While the surfaces of the ridges are dry grasslands, there is often standing water in the swales, Skalbeck said.

The Nature Conservancy last month paid $700,000 for the water-holding 58.6 acres west of the rail line and north of 126th St., according to state and county real estate records. In 2014, the group purchased a separate 30.8-acre parcel west of the rail line near 116th St. to preserve that open space for its role in feeding water to the wetlands.

The group has purchased more than 330 acres of ridges and swales east of the rail line since 1965 in what is now the Chiwaukee Prairie natural area. In 2015, the group donated 150 acres to the state Department of Natural Areas for public recreation. A separate block of land was given to UW-Parkside for scientific study. Remaining acres owned by TNC are open to the public.

Chiwaukee Prairie is one of only 38 "Wetlands of International Importance" in the United States designated as globally significant under an international treaty known as the Ramsar Convention. Others include Everglades National Park in Florida, Chesapeake Bay estuary in Virginia and a complex of coastal wetlands along Lake Michigan in northern Door County.

One requirement for attaining the Ramsar designation is evidence that wetlands provide habitat for rare and endangered species and contain a rich biological diversity. Among the 26 rare plants at Chiwaukee Prairie are eastern prairie fringed orchid and marsh blazing star.

For diversity, Chiwaukee Prairie is home to more than 400 species of plants. Around 75 species of grassland and wetland birds have been observed there during the breeding season.

The natural area harbors one of the largest prairies in the state and the most intact coastal wetland in southeastern Wisconsin, according to the DNR. The wide ridges support prairie and oak savanna. The swales contain a variety of wetland plant communities: sedge meadow; wet prairie; calcareous fen; shrub carr and even shallow marsh.

Chiwaukee Prairie is part of a narrow plain that extends along the lakeshore from the beach dunes south of Kenosha to North Chicago, Ill. A series of parallel ridges on the plain mark former shorelines and show changes in the lake level as it receded from the bluff.

Each ridge contains sand, gravel and other sediment deposited by storm waves. As the lake level dropped, another ridge would form and enclose a swale.

The ridges form a "washboard" landscape that is most prominent south of Zion, Ill., Skalbeck said. The National Park Service has recognized the alternating ridges and swales south of Kenosha as a National Natural Landmark.