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Rare animals
Find rare and non-game animals.
Rare plants
Learn about plants on the Natural Heritage Working List.
Rare lichens
Discover Wisconsin's lichens.
Natural communities
Explore Wisconsin's natural communities.
Other features
Discover unique resources.
Contact information
For information on Wisconsin's natural communities, contact:
Ryan O'Connor
Natural Heritage Inventory Assistant Ecologist



General natural community overview

Impoundments (also known as reservoirs) are artificially created standing water bodies, produced by dams on streams or rivers. Because of the diverse nature of streams, rivers, and dams, these waterbodies can vary greatly in size, configuration, flow patterns, water chemistry, and biota. Impoundments are nearly as numerous and diverse in characteristics as natural lakes, with larger and more southerly waters having the richest fish faunas. Most often the waterbodies are dominated by warmwater fishes, particularly the family Centrarchidae (sunfishes).

Rare animals

Species of Greatest Conservation Need

Note: The information presented here comes from the 2005 Wisconsin Wildlife Action Plan. The 2015 revision has been submitted to the U.S. Fish and Wildlife Service for approval. Our website content will be updated when the plan has been approved.

The following Species of Greatest Conservation Need are listed according to their level of association with the natural community type, based on the findings in Wisconsin's 2005 Wildlife Action Plan.

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Bald EagleHaliaeetus leucocephalus3
OspreyPandion haliaetus3
American Golden PloverPluvialis dominica2
Black TernChlidonias niger2
Blue-winged TealAnas discors2
CanvasbackAythya valisineria2
DunlinCalidris alpina2
Forster's TernSterna forsteri2
Lesser ScaupAythya affinis2
Short-billed DowitcherLimnodromus griseus2
Trumpeter SwanCygnus buccinator2
Caspian TernSterna caspia1
Common TernSterna hirundo1
Horned GrebePodiceps auritus1
Hudsonian GodwitLimosa haemastica1
Marbled GodwitLimosa fedoa1
WhimbrelNumenius phaeopus1

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
MooseAlces alces2
Eastern Red BatLasiurus borealis1
Hoary BatLasiurus cinereus1
Northern Long-eared BatMyotis septentrionalis1
Silver-haired BatLasionycteris noctivagans1
Water ShrewSorex palustris1

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Reptiles and AmphibiansScore
Boreal Chorus FrogPseudacris maculata3
Mink FrogRana septentrionalis3
MudpuppyNecturus maculosus3
Northern Cricket FrogAcris crepitans3
Pickerel FrogRana palustris3

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Lake SturgeonAcipenser fulvescens3
Black BuffaloIctiobus niger2
Greater RedhorseMoxostoma valenciennesi2
Redfin ShinerLythrurus umbratilis2

Please see the Wildlife Action Plan, Chapter 2.4 to learn how this information was developed.


Management Opportunities

The following Ecological Landscapes have the best opportunities to manage for , based on the Ecological Landscapes of Wisconsin Handbook.

Map of the Ecological Landscapes of Wisconsin.

Major (3 on map)
A major opportunity for sustaining the natural community in the Ecological Landscape exists, either because many significant occurrences of the natural community have been recorded in the landscape or major restoration activities are likely to be successful maintaining the community's composition, structure, and ecological function over a longer period of time.

Important (2 on map)
Although the natural community does not occur extensively or commonly in the Ecological Landscape, one to several occurrences do occur and are important in sustaining the community in the state. In some cases, important opportunities may exist because the natural community may be restricted to just one or a few Ecological Landscapes within the state and there may be a lack of opportunities elsewhere.

Present (1 on map)
The natural community occurs in the Ecological Landscape, but better management opportunities appear to exist in other parts of the state.


Note: The information presented here comes from the 2005 Wisconsin Wildlife Action Plan. The 2015 revision has been submitted to the U.S. Fish and Wildlife Service for approval. Our website content will be updated when the plan has been approved.

These threats and priority conservation actions were identified for the community type in Wisconsin, and they apply to all of Wisconsin's Ecological Landscapes unless otherwise indicated. Please see the Wisconsin Wildlife Action Plan, Chapter 3.3 , for more information


  • Watershed and riparian land use practices and resulting non-point source pollution are leading to habitat loss and eutrophication.
  • Water-level manipulations are degrading nearshore and littoral-zone habitats in some waterbodies.
  • Shoreline and littoral-zone alteration and development are degrading habitat.
  • Mercury bioaccumulation in fish poses a health risk to humans and other animals that eat fish, especially in waters with sediments that increase the rate of mercury methylization. Sediment characteristics appear to make impoundments more susceptible to higher rates of mercury methylization than other water body types.
  • Exotic aquatic plant and animal species are degrading habitat, altering food webs, and reducing and displacing desirable native species.

Conservation actions

  • Improve watershed land-use practices to reduce non-point source pollution.
  • Establish water-level management regimes that more closely mimic natural water level fluctuations.
  • Protect and restore shoreline and littoral-zone habitat.
  • Continue to seek statewide and regional reductions in mercury emissions from key sources.
  • Improve regulations and education to prevent the introduction of additional exotic species and to help control and limit the spread of existing populations.




Northeast of New London, showing dikes and impoundments in floodplain, Outagamie County.

Photo by Eric Epstein.


Turtle-Flambeau Flowage, Iron County.

Photo by  staff.


Chippewa Flowage, Sawyer County.

Photo by  staff.


Aerial view of Lake Wisconsin, Columbia County.

Photo by Edward Smith.

Note: photos are provided to illustrate various examples of natural community types. A single photograph cannot represent the range of variability inherent in a given community type. Some of these photos explicitly illustrate unusual and distinctive community variants. The community photo galleries are a work in progress that we will expand and improve in the future.

Last revised: Thursday, September 24, 2015