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National Water Summary-Wetland Resources 231 Michigan Wetland Resources Wtlands cover about 15 percent of Michigan. They are ecologi­ There is no current ( 1993) estimate of statewide wetland acre­ cally and economically valuable to the State. Wetlands provide shore­ age in each of the systems. However, the Michigan Department of line protection as well as temporary flood storage. Wetlands pro­ Natural Resources has inventoried land cover and land use; the re­ tect water quality by removing excess nutrients and sediments from sult is the Michigan Resource Inventory System (MIRIS). Wetland surface and ground water. Michigan's wetlands, such as Tobico classifications were developed specifically for this inventory sys­ Marsh shown in figure I, provide important wildlife habitat and have tem. Classes of wetlands under this scheme are lowland conifers, a significant role in maintaining a high level of biological diversity. 1.826,402 acres; lowland hardwoods, 2,484,430 acres; wooded Most freshwater fi sh depend on wetlands at some stage in their life wetland, 263,684 acres (palustrine forested wetlands under the cycle. Birds use wetlands as migratory resting places, fo r breeding Coward in and others L1 979] classification system); shrub/scrub wet­ and feeding grounds, and as cover from predators. Wetlands, such land, I, 186,150 acres (palustrine scrub-shrub wetlands); aquatic­ as those in Seney National Wildlife Refuge, are a preferred habitat bed wetland, 60,863 acres (rooted and floating vascul ar aquatic-bed for muskrat, beaver, otter, mink, and raccoon. Some rare or threat­ wetlands); emergent wetland, 4 I 9,061 acres (persistent- and non­ ened animals rely on wetl ands, and 9 1 of 238 plant species listed as persistent-emergent wetlands; and unvegetated flats, 3,926 acres threatened or endangered by the State grow in wetland habitats (unconsolidated-shore wetlands). The results of the MIRIS inventory (Cwikiel, 1992). Wetlands benefit the State's tourist and outdoor are similar to the 1953 U.S. Fish and Wildlife Service inventory recreation industries by providing opportunities for activities such (U.S. Fish and Wildlife Service, 1955); wooded and scrub/shrub as hunting, fi shing, trapping, hiking, canoeing, birdwatching, na­ wetlands are the most common wetland types in Michigan. Emer­ ture photography, and viewing wildflowers. Blueberries and wild gent wetlands make up a relatively small percentage of the State's r ice are produced commercially in Michigan wetlands. In the early total wetlands. ! 980's, Michigan was one of five States that together produced 75 Wetlands were estimated by Dahl (1990) to occupy about 5.6 percent of the peat mined in the United States. million acres of Michigan in the mid-I980's. There are more than 6.2 million acres of wetlands classified under MIRIS. However, under TYPES AND DISTRIBUTION the classification scheme for MIRIS, lowland conifers and lowland hardwoods are primarily wetl ands but may also include some areas Wetlands are lands transitional between terrestrial and deep­ that would be defined as uplands based on regulatory definitions water habitats where the water table usually is at or near the land (Michigan Department of Natural Resources, 1992). surface or the land is covered by shallow water (Cowardin and oth­ In 1972, the Department of Natural Resources conducted a ers, 1979). The distribution of wetl ands and deepwater habitats in shore lands inventory and identified l 05,855 acres of Great Lakes Michigan is shown in figure 2A; only wetlands are discussed herein. coastal wetlands (Michigan Department of Natural Resources, Wetlands can be vegetared or nonvegetared and are classified 1973). lt has been estimated that coastal wetland acreage in Michi­ on the basis of their hydrology, vegetation, and substrate. In this gan has been as much as 369,000 acres in the past (Jaworski and summary, wetlands are classified according to the system proposed Raphael, 1978). Michigan coastal wetlands are distributed among by Cowardin and others ( 1979), which is used by the U.S. Fish and the Great Lakes in the following proportions: 37 percent along Lake Wildlife Service (FWS) lo map and inventory the Nation's wetl ands. Huron; 28 percent along Lake Michigan; 16 percent along the St. At the most general level of the classification system, wetlands are Clair River, Lake St. Clair, and the Detroit River area; 13 percent grouped into five ecological systems: Palustrine, Lacustrine, Riv­ along Lake Superior; and 6 percent along Lake Erie (Michigan erine, Estuarine, and Marine. The Palustrine System includes only Department of Natural Resources, l 992). wetlands, whereas the other systems comprise wetlands and deep­ water habitats. Wetlands of the systems that occur in Michigan are described below. System Wetland description Palustrine .................. Wetlands in which vegetation is predominantly trees (forested wetlands); shrubs (scrub-shrub wetlands}; persistent or non persistent emergent, erect, rooted, herbaceous plants (persistent- and nonpersistent-emergent wetlands); or sub­ mersed and (or) floating plants (aquatic beds). Also, intermittently to permanently flooded open-water bodies of less than 20 acres i n which water ,s less than 6.6 feet deep. Lacustrine ................. Wetlands within an intermittently to permanently flooded lake or reservoir. Vegetation, when pres­ ent, is predominantly nonpersistent emergent plants (nonpersistent-emergent wetlands), or submersed and (or) floating plants (aquatic beds). o r both. Figure 1. Tobico Marsh, a coastal wetland along the shore Ri verine ..................... Wetlands within a channel. Vegetation, when pres- of Saginaw Bay. (Photograph by Erin A. Lynch, U.S. Geo­ ent, is same as in the Lacustrine System. logical Survey.) 232 National Water Summary-Wetland Resources: STATE SUMMARIES Along Lake Michigan from Muskegon north to Empire, wet­ lands are associated with wide, low-gradient tributary mouths that extend inland for several miles. Beaver Island has extensive wetlands. The shoreline from Empire to the Straits of Mackinac contains few wetlands. The Upper Peninsula shoreline of Lake Michigan is com­ posed of rocky points and headlands with sandy or marshy bay heads - Isle Royale National Par1< (Herdendorf and others, 1981 ). Along the Lake Superior shoreline of Michigan, wetlands are most common along the Keweenaw Bay waterway and at tributary mouths in Marquette and Chippewa Counties. The Isle Royale shore­ line and islands and the mainland shores of the St. Marys River contain wetlands (Herdendorf and others, 198 I ). The Michigan shoreline of western Lake Erie consists oflow­ lying marshes (emergent wetland) and sand beaches (unconsoli- _ s,__ •;. ~ - ~ f ~ Drummond " •..,_ ~ ~Island ~ t!ic: a~·~;.:. 46 ... -·- " "~_,.,,,,. ~8 Beaver lslandf}{) < J ' 0 25 50 MllfS ....c ~ 0 25 50 KILOMETERS .,.<"" ' A WETLANDS AND DEEPWATER HABITATS Distribution of wetlands and deepwater habitats- This map shows the approximate distribution of large wetlands in the State. Because of limitations of scale and source material, some wetlands are not shown • Predominantly wetland Predominantly deepwater habitat ~ Area typified by a high density of small wetlands Figure 2. Wetland distribution and climatological features in Michigan. A, Distribution of wetlands and deepwater habitats. (Source: A, T.E. Dahl, U.S. Fish and Wildlife Service, unpub. data, 1991.) National Water Summary- Wetland Resources: MICHIGAN 233 dated-shore wetland). The shoreline of Lake Huron from the Straits a function of climatic, physiographic, and hydrologic factors such of Mackinac to Drummond Island generally consists of plains al­ as precipitation and runoff patterns, evaporation potential, topog­ ternating with outcrops of limestone and dolomite. These plains are raphy, and configuration of the water table. In Michigan, a favor­ generally composed of clays and contain marshes. The beaches able water budget coupled with impeded drainage promotes ample along the northern part of the Saginaw Bay are occasionally inter­ soil moisture for wetland development in depressions, many of which rupted by wetlands. Most of the southeastern part of Saginaw Bay were formed by glaciation. Precipitation (fig. 28) in the form of is marshy with shallow water inshore. From Sand Point to Port rain and snow averages approximately 3 1 inches annually. Lake­ Austin the shore is composed of sand beaches with a bluff of un­ effect precipitation is prevalent in near-shore areas but also affects even sand ridges. The sand ridges parallel the shoreline and alter­ areas farther inland. Surface waters, including wetlands, are con­ nate with wetlands. The area from Port Hope to the St. Clair River stantly replenished by precipitation. Runoff (fig. 2C) varies geo­ contains few wetlands. Along Lake St. Clair. the St. Clair River, and graphically and seasonally. It is greatest in areas where snowfall the Detroit River, the only extensivt: natural art:as that havt: not bt:t:n accumulation is heaviest (Miller and Twenter, 1986). developed are the St. Clair River Delta wetlands and wetlands on The topographic character of Michigan was largely determined islands at the mouth of the Detroit River (Herdendorf and others, by glaciation. Glacial lobes channeled through parts of the Great 1981). Lakes and deposited thick layers of drift material. The bulk of this Approximately 18,000 acres of wetlands line Saginaw Bay ( 15 drift accumulation may have been developed before the latest gla­ percent of the drainage basin) and comprise the largest remaining cial period. Areas bordering the Lower Peninsula and in a broad belt freshwater coastal wetland system in the Nation. Tobico Marsh (fig. extending southwest from the Saginaw River Basin beyond Lansing I) is an enclosed lagoon bordered on the east by a narrow coastal consist of flat drift deposits. Glacial lake waters covered much of barrier at Saginaw Bay and on the west by sand ridges. Emergent these areas. There are more than 35,000 mapped lakes and ponds, wetlands occupy approx imately 1.260 acres ofTobico Marsh. They and 36,350 miles of rivers and streams in Michigan (Sweat and Van contain many bird species and are attractive to waterfowl during Til, 1987).

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