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Dune and Swale Wetlands in the Sleeping Bear Dunes National Lakeshore

March 1, 1997 | By Hans Voss
Great Lakes Bulletin News Service

Dune and Swale Wetlands in the Sleeping Bear Dunes National Lakeshore

Freshwater dune and swale wetland types, a globally rare and unique resource, are found exclusively along Great Lakes shorelines. These wetlands are interspersed between sand dunes that were formed thousands of years ago when runoff from receding glaciers filled low-lying areas with fresh water.

The Sleeping Bear Dunes National Lakeshore boasts a 2,600-acre dune and swale complex near Platte Bay. An aerial view shows a series of arcs fanning out over two miles, generally following the contours of the existing shoreline.

Swales are dominated by open marsh, with grasses, sedge, and ferns. The Benzie County dune and swale wetlands sustain at least one bald eagle nest, and support four plant species that are on the state and federal "threatened" lists.

The public can explore the Park's dune and swale wetlands via Boekeloo Road, Peterson Road, and the Platte Plains hiking trail off M-22.

Platte River and Platte Lakes Wetlands

Wetlands are a chief reason for the clear water and excellent fish habitat of the upper Platte River. Mixed conifer and hardwood wetlands found along the length of the river and its tributaries protect the river from runoff and erosion.

As the Platte River approaches Big and Little Platte lakes the wetlands progress to a vast tamarack and cedar swamp. This type of wetland typically contains very wet, mucky, organic soils. Standing dead trees, known as snags, provide important habitat for small animals, insects, and birds such as bald eagles and owls.

Much of the Platte tamarack and cedar swamp is state-owned, and is reachable from Deadstream Road.

Herring Lakes Wetlands

In southwest Benzie County, there are 2,500 acres of beautiful wetlands surrounding Upper Herring Lake that are vital to maintaining the water quality of both Upper and Lower Herring lakes.

*On the east side of Upper Herring Lake lies a mixed conifer and hardwood wetland that is so healthy that it supports a thriving bobcat population, according to local residents. Small streams flow out of the wetland and feed the lake. Agriculture and residential development have caused some losses, but much of this large, privately-owned wetland is still intact.

*On the west side of Upper Herring Lake is the 123-acre Upper Herring Lake Preserve, which is owned and managed by the Grand Traverse Regional Land Conservancy. It includes upland meadows, willow-dogwood swamp, and willow-poplar swamp. Walking trails are maintained throughout the preserve, and can be reached from M-22 just south of Matzinger Resort Road.

Small Wetlands Are Also Important

Smaller, less recognized wetlands offer many of the same benefits as larger wetlands. They provide vital flood control; collect water and release it slowly into the ground to replenish aquifers; and provide important localized habitat for wildlife. The fact that many small wetlands are not always regulated by wetland laws does not diminish their importance.

State and Local Trends in Wetland Loss

Since Michigan was settled in the late 1700s more than 5.6 million acres of wetlands have disappeared. Fifty percent of the state's inland wetlands have been lost, and 70% of the coastal wetlands have been destroyed. This massive change to the landscape has caused increased flooding, water pollution, and diminished wildlife.

A significant amount of wetlands continue to disappear in Michigan, much of it allowed under state and federal law. Permitted fills for commercial and industrial development, housing, roads, agriculture, and logging claim an estimated 500 acres of wetlands statewide each year.

There are also losses from unpermitted wetland filling. It is difficult to determine the amount of wetland acreage that is ruined this way -- according to one conservative estimate, the loss in Michigan is roughly 500 acres annually.

The Michigan Land Use Institute estimates that Benzie County's portion of this overall wetlands loss is at least 3 acres per year. This figure was derived from the following information:

*Department of Environmental Quality records indicate an average of half an acre per year is lost in Benzie County due to permitted fills.

*DEQ records between 1991 and 1996 document that on average 1.25 acres per year are lost as a result of wetland fills that occur in violation of the state wetland protection laws.

*The Michigan Land Use Institute estimates that the DEQ documents only half of the illegal wetland fills. Thus, some 1.25 acres of wetlands are lost each year as a result of undocumented illegal fills. In addition to the loss of wetlands, seemingly subtle changes to the land in a watershed can affect the quality of wetlands. The construction of roads, parking lots, and buildings reduces the area that allows water to percolate into the soil, thus increasing runoff to wetlands. Roads built through wetlands can disrupt the hydrology of a wetland and cause flooding. And drains and ditches built for agriculture and other development can dry out wetlands.

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