Valvata winnebagoensis
Flanged valvata

Key Characteristics

The flanged valvata is a freshwater snail characterized by a small shell (to .2 inches diameter), with 3 prominently ribbed and angled whorls resembling stacked cylinders when viewed from the side. The spire is low and the aperature wide, of a semicircular shape. The snail itself features a single feathery gill on the left side and a tentacle on the right.

Status and Rank

  • State Status: SC
  • State Rank: SNR
  • Global Rank: G2?


No known occurrences in Michigan

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


This species can be found in cold, clean lakes and ponds (Minton 2004, Burch 1988).

Specific Habitat Needs

Clear needed in Inland Lake, Littoral, Benthic, Inland Lake, Pelagic, Benthic, Great Lake, Littoral, Benthic

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.


Major changes to aquatic environments through impoundment, dredging and channelization can negatively affect aquatic snails through the fragmentation of populations and increased sedimentation, which can physically bury individuals and eliminate sources of food (Johnson 2009). Acidification of waterbodies decreases available calcium, sometimes resulting in thin-shelled snails, increasing vulnerability to predation (Brown 1991). Waters with a pH below 5 have been found incapable of supporting snail life (Okland 1992).  Acid rain reduction efforts will therefore be a positive step toward aquatic snail management.  Heavy metal and chemical pollution from agricultural and urban runoff, industrial waste, and pesticide treatment is lethal to many snail species, even at low exposure levels (Besser et al. 2007, Johnson 2009, Kosanke et al 2004). Efforts to improve water quality will benefit this group.

Active Period

Active from first week of June to first week of October

Survey Methods

There are several effective methods for conducting aquatic snail surveys. Areas of coarse cobble substrate are best surveyed with a glass-bottomed bucket or scuba search, and hand collecting. Stones and sunken pieces of wood can be picked up, searched, and replaced. Dip net suveys are employed at soft substrate locations. Aquatic vegetation held over a bucket and vigorously shaken to remove individual snails is another technique (Groves 2007).

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Aug 17, 2018]


Survey References

Technical References

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