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Environmental Corridors

The Commission has defined, mapped, and long recommended protecting environmental corridors to help preserve the Region’s most important remaining natural resource elements.

Environmental Corridors

Environmental corridors are typically elongated areas in the landscape that encompass the most important elements of the Region’s natural resource base. These important elements include the best remaining woodlands, wetlands, prairies, significant wildlife habitat areas, surface water and associated floodplains and riparian buffers, and natural areas and critical species habitat sites, together with many related historic, scenic, and recreational sites.

Commission regional plans have long recommended that these corridors be preserved in essentially natural, open uses. This helps to protect the quality of the Region’s surface and ground water resources and the past and ongoing development-related investments made by communities across the Region.


Delineating Corridors

The Commission has been identifying environmental corridors since the 1960s, when the environmental corridor concept was included in the Commission’s first regional land use plan. An initial detailed mapping of all the elements of the natural resource base, along with regular updating of certain key elements of the natural resource base, and the inclusion of the most up-to-date information available, serves as the basis for corridor delineation.

Commission staff inventory certain natural resource features and delineate all environmental corridors every five years using the best available orthophotography. Because of the importance of these environmental corridors, State, county, and local governments frequently call upon our staff to verify and stake in the field the boundaries of the corridors and/or certain key features such as wetlands, woodlands, natural areas, etc. More information can be found on the Environmental Fieldwork page.

These inventories have resulted in the delineation of environmental corridors, which are shown on this environmental corridors map and can be accessed through the Commission’s Interactive Mapping Application. The delineation process is technically defined in this article on delineating environmental corridors.


Categorizing Environmental Corridors

The Commission has specifically identified what are termed primary environmental corridors, secondary environmental corridors, and isolated natural resource areas:


Square Miles

Primary Environmental Corridors

Concentrations of significant natural resources at least 400 acres in area, at least two miles in length, and at least 200 feet in width. Comprise 18% of the Region.



Square Miles

Secondary Environmental Corridors

Concentrations of significant natural resources at least 100 acres in area and at least one mile in length. Comprise 3% of the Region.



Square Miles

Isolated natural resource areas

Those remaining significant natural resources at least five acres in area and at least 200 feet in width. Comprise 3% of the Region.


Preserving Environmental Corridors

Commission plans, including VISION 2050, recommend preserving environmental corridors in essentially natural, open uses. While the term “preserve” generally means to retain in existing conditions, the Commission has determined that certain types of uses can be accommodated while maintaining the overall integrity of the existing resources when used in relation to environmental corridors (guidelines for development compatible with environmental corridors). Otherwise, new urban development should avoid these environmental corridor lands, particularly the primary environmental corridors.

To the extent possible, new urban development should also avoid secondary environmental corridors and isolated natural resource areas, and should attempt to preserve other wetlands, woodlands, natural areas, critical species habitat sites, and park and open space sites outside environmental corridors.

Primary environmental corridors: VISION 2050 recommends that local and county governments should incorporate corridor preservation recommendations and related guidelines in their land use policies, including comprehensive plans and land use ordinances.

Secondary environmental corridors and isolated natural resource areas: VISION 2050 recommends that local and county governments consider preserving these corridors as natural, open space; or as drainageways, stormwater detention or retention areas, or as local parks or recreation trails where appropriate, as determined in local plans.

Implementing the above environmental corridor protection recommendations is envisioned to come about primarily through enactment of appropriate zoning regulations at the county and local levels of government. Links to model regulations and standards for protecting natural resource elements are available on the Zoning and Ordinances page.

It is important to note that certain policies adhered to by the Wisconsin Department of Natural Resources and the Wisconsin Department of Safety and Professional Services, in their regulation of sanitary sewerage systems, may prohibit or otherwise limit sewered development within environmental corridors and isolated natural resource areas. More information on this subject may be found in the VISION 2050 planning report (pages 156-157).

Inventories undertaken for VISION 2050 indicate that about 460 square miles of primary environmental corridor are substantially protected and preserved through ownership and/or public land use regulation as of 2015. This totals about 94% of the primary corridors in the Region. This protection of primary environmental corridors map shows those that are protected and unprotected.