What is a Wetland?

Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season.

Water saturation (hydrology) largely determines how the soil develops and the types of plant and animal communities living in and on the soil. Wetlands may support both aquatic and terrestrial species. The prolonged presence of water creates conditions that favor the growth of specially adapted plants (hydrophytes) and promote development of characteristic wetland (hydric) soils. Wetlands are found from the tundra to the tropics and on every continent except Antarctica.

Two general categories of wetlands are recognized: coastal or tidal wetlands and inland or non-tidal wetlands.

Coastal/Tidal Wetlands

In the United States, as their name suggests, coastal/tidal wetlands are found along the Atlantic, Pacific, Alaskan, and Gulf coasts. They are closely linked to our nation's estuaries where sea water mixes with fresh water to form an environment of varying salinities.

Inland/Non-tidal Wetlands

These wetlands are most common on floodplains along rivers and streams (riparian wetlands), in isolated depressions surrounded by dry land (for example, playas, basins and "potholes"), along the margins of lakes and ponds, and in other low-lying areas where the groundwater intercepts the soil surface or where precipitation sufficiently saturates the soil (vernal pools and bogs). Inland wetlands include marshes and wet meadows dominated by herbacious plants, swamps dominated by shrubs, and wooded swamps dominated by trees. Certain types of inland wetlands are common to particular regions of the country.

Many of these wetlands are seasonal (they are dry one or more seasons every year) and, particularly in the arid and semiarid West, may be wet only periodically. The quantity of water present and the timing of its presence in part determine the functions of a wetland and its role in the environment. Even wetlands that appear dry at times for significant parts of the year―such as vernal pools―often provide critical habitat for wildlife adapted to breeding exclusively in these areas.

Threats to Wetlands

By 1984, over half (54%) of all wetlands in the U.S. had been drained or filled for development or agriculture. Congress responded to these alarming figures by passing two critical wetland conservation and restoration federal programs administered by the National Resources Conservation Services (NCRS) to slow or reverse these alarming trends.

During a period of approximately 15 years at the end of last century, the continental breeding duck population fell from 45 million to 31 million birds, a decline of 31 percent. Draining wetlands for agricultural purposes is significant, but declining, while development pressure is emerging as the largest cause of wetland loss. Many of the created wetlands fail to replace the diverse plant and animal communities of those destroyed.

When a wetland functions properly, it provides water quality protection, fish and wildlife habitat, natural flood water storage, and reduction in the erosive potential of surface water. A degraded wetland is less able to effectively perform these functions. For this reason, wetland degradation is as big a problem as outright wetland loss, though often more difficult to identify and quantify.

While wetlands only cover about 5% of the lower 48 states land surface, they support 31% of the plant species.

Pollution inputs

Although wetlands are capable of absorbing pollutants from the surface water, there is a limit to their capacity to do so. The primary pollutants causing wetland degradation are sediment, fertilizer, human sewage, animal waste, road salts, pesticides, heavy metals and selenium.

Nearly 75% of all wetlands are privately owned, making it imperative that the public participate in wetland management and protection.

Wetlands in our Kewaunee/Door County area include:

*  Black Ash Swamp
* Kangaroo Lake
* Mink River Estuary
* Moonlight Bay & connected wetlands
* North Bay
* Shivering Sands & connected wetlands

By Robert Sijgers, Director

Sources:
Environmental Protection Agency
National Resources Conservation Services
Wisconsin Wetlands Association