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Contact information
For information on State Natural Areas, contact:
Thomas Meyer
Natural areas conservation biologist

Wisconsin State Natural Areas Program Mukwonago River (No. 417)

Longear sunfish

Photo by Thomas A. Meyer


Overview

Location

Waukesha County. T5N-R18E, Section 36. 44 acres.

Description

Description

The Mukwonago River is among the cleanest and most biologically diverse streams in southeastern Wisconsin and provides critical habitat for a number of rare, threatened, and endangered species of fish and invertebrates. Between Eagle Spring and Phantom Lakes, the river is designated an Exceptional Resource Water, with clear, warm water and a maximum depth of 2'. The bottom is composed of sand, rocks and gravel and contains many large glacial boulders. At least 53 species of fish, including the state-threatened longear sunfish (Lepomis megalotis) and state-endangered starhead topminnow (Fundulus dispar) have been found here. In fact, the two-mile stretch of river from the natural area downstream to its confluence with the Fox River, contains the last known self-sustaining longear sunfish population in Wisconsin. Among the other fish inhabiting the stream are grass pickerel, rosyface shiner, sand shiner, banded killifish, tadpole madtom, rainbow darter, and brook silverside. Longnose gar are often seen patrolling the waters. Equally diverse is the freshwater mussel fauna. This reach of the Mukwonago is one of the most biologically-rich mussel habitats in the state. Sixteen species are found here, including Wisconsin's only remaining viable population of the state-endangered rainbow shell (Villosa iris). Rare dragonflies known from the stream are the fragile forktail (Ischnura posita) and the double-striped bluet (Enallagma basidens). Beds of coontail and other submerged aquatics are common in the stream, while the banks contain bulrushes, sedges and other emergent plant species. The 44-acre State Natural Area lies within the larger Mukwonago River watershed corridor, a mosaic of natural communities including forest, savanna, wetlands, and lakes. This diverse landscape is home to a wide array of native plants and animals and is an important stopover site for a number of Neotropical migratory birds. Mukwonago River is owned by the DNR and was designated a State Natural Area in 2005.

Access

Driving directions

From the intersection of County ES and State Highway 83 in Mukwonago, go south on 83 0.8 mile to a park and ride on the north side of the highway.

Ownership

Mukwonago River is owned by:

  • WDNR

Maps

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.

Management

Site objectives

Manage the site as a reserve for stream and springs, as an aquatic reserve and wetland protection area, and as an ecological reference area. Natural processes will determine the structure of the stream and wetlands. Provide opportunities for research and education on the highest quality native streams and wetlands.

Management approach

The passive management of the stream and maintenance of woody cover on the banks will determine the ecological characteristics of the site. Other allowable activities include control of invasive plants and animals, maintenance of existing facilities, and access to suppress wildfires. Salvage of trees after a major wind event can occur if the volume of woody material inhibits fire prescriptions.

Site-specific considerations

  • Illegal collection of freshwater mussels has reduced their populations. Posting of collection rules and enforcement is an ongoing activity.

Recreation

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

  • Horseback riding
  • Rock climbing
  • Vehicles, including bicycles, ATVs, aircraft, and snowmobiles except on trails and roadways designated for their use
  • Collecting of animals, 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
  • Camping and campfires
  • Geocaching

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

Last revised: Tuesday, October 21, 2014