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Wisconsin State Natural Areas Program Mud Lake Fen and Wet Prairie (No. 604)

Mud Lake Fen and Wet Prairie

Photo by Josh Mayer



Within Lake Mills Wildlife Area, Jefferson County. T7N-R13E, Section 26. 149 acres.



Situated on the south shore of Mud Lake, this natural area features a narrow band of calcareous fen adjacent to the inlet stream to Mud Lake. The black, peaty soil is quaking in some areas and supports a diverse flora. Big bluestem, satin grass, bluejoint grass, and sedges dominate. Other typical species include Ohio goldenrod, grass-of-parnassus, kalm's lobelia, lousewort, lesser fringed gentian, Riddell's goldenrod, marsh bellflower, marsh vetchling, boneset, fringed brome, swamp aster, and great blue lobelia. Small springs and spring runs emanate from the site and flow into the Mud Lake inlet. Near the inlet stream, the mat vegetation is floating and composed mostly of sedges. To the north is Mud Lake, a 93-acre hard water drainage lake. Woody species including willows, tamarack, and silky dogwood have increased in abundance due to lack of fire, which historically occurred in the area. Management objectives include using prescribed burning to simulate natural processes which can help reduce the impact of the woody species on the native fen community. Mud Lake Fen and Wet Prairie is owned by the DNR and was designated a State Natural Area in 2010.


Driving directions

From the intersection of Highway 89 and Mud Lake Road in Lake Mills, go south on Mud Lake Road 1.8 miles, then west on Conservation Road 0.25 miles, then north to a DNR parking area.


Mud Lake Fen and Wet Prairie is owned by:

  • WDNR


The DNR's state natural areas program is comprised of lands owned by the state, private conservation organizations, municipalities, other governmental agencies, educational institutions and private individuals. While the majority of SNAs are open to the public, access may vary according to individual ownership policies. Public use restrictions may apply due to public safety, or to protect endangered or threatened species or unique natural features. Lands may be temporarily closed due to specific management activities. Users are encouraged to contact the landowner for more specific details.

The data shown on these maps have been obtained from various sources, and are of varying age, reliability, and resolution. The data may contain errors or omissions and should not be interpreted as a legal representation of legal ownership boundaries.


Site objectives

Restore and enhance the quality of the fen and wet prairie. Manage the site as a reserve for wet prairie, and calcareous fen, and as an aquatic reserve and wetland protection site, and as an ecological reference area. Natural processes and prescribed fire will determine the structure of the wetlands. Provide opportunities for research and education on the highest quality native wetland communities.

Management approach

In areas undergoing conversion from wet prairie to shrubs and brush, use prescribed fire, mechanical mowing, and herbicide to remove the woody vegetation. Due to the sensitivity of fen soils, any removal of encroaching woody material should usually be by hand methods, prescribed fire, or by vehicles on frozen ground. On sites dominated by monotypic stands of reed canary grass, where practicable use prescribed fire, mowing, and herbicide to reduce competition to the native vegetation. For the fen, manage the surrounding lands, as well as groundwater resources, to preserve the fen's hydrologic function.

Site-specific considerations

  • Historically, fire played a key role in maintaining many of the fens in southern Wisconsin. The lack of fire on the present landscape has contributed to the encroachment of woody species on open fen habitat, with the consequent suppression or loss of some of the more light-demanding herbs.
  • Vehicular traffic, and overuse by hikers of other recreationists can physically damage the surface of the fen and destroy sensitive vegetation.


Management objectives and prescriptions

  • Remove invasive species including non-native phragmites and canary grass.
  • Conduct prescribed burns to simulate natural processes to reduce the impact of woody species including silky dogwood, tamarack, and willows.


Very few State Natural Areas have public facilities, but nearly all are open for a variety of recreational activities as indicated below. Generally, there are no picnic areas, restrooms, or other developments. Parking lots or designated parking areas are noted on individual SNA pages and maps. Trails, if present, are typically undesignated footpaths. If a developed trail is present, it will normally be noted on the SNA map and/or under the "Access" tab. A compass and topographic map or a GPS unit are useful tools for exploring larger, isolated SNAs.

Allowable activities

In general, the activities listed below are allowed on all DNR-owned SNA lands. Exceptions to this list of public uses, such as SNAs closed to hunting, are noted under the "Access" tab above and posted with signs on site.

  • Hiking
  • Fishing
  • Cross country skiing
  • Hunting
  • Trapping

Prohibited activities

  • Camping and campfires
  • Collecting of animals (other than legally harvested species), non-edible fungi, rocks, minerals, fossils, archaeological artifacts, soil, downed wood, or any other natural material, alive or dead. Collecting for scientific research requires a permit issued by the DNR
  • Collecting of plants including seeds, roots or other non-edible parts of herbaceous plants such as wildflowers or grasses
  • Drone use, unless authorized by a SNA research permit
  • Geocaching
  • Horseback riding
  • Rock climbing
  • Vehicles, including bicycles, ATVs, aircraft, and snowmobiles except on trails and roadways designated for their use

For rules governing state-owned SNAs and other state lands, please consult Chapter NR 45 Wis. Admin. Code [exit DNR]

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Last revised: Friday, December 15, 2017