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Geology and Water
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Wetlands

Red ball iconWetlands


Wetlands and geology are not a connection most people think of and yet geology plays a vital role in the development and maintenance of wetlands. The Geological Survey Bureau has been involved in several wetland studies, most prominently an investigation of groundwater-fed wetlands known as fens. Iowa fens are small, nutrient-rich peatlands with circum-neutral or higher pH and a dominantly calcium-bicarbonate water chemistry. Although fens are common components of the landscape in many northern European countries, parts of Canada, and some northern U.S. states, little was known about the small hillslope fens found in the midwest and prairie states. Fens may be one of the rarest wetland communities in the midwest and are valued for their botanic diversity. Over 200 species of plants, many of which are endangered, threatened, or rare, are known to occur in fens; some are found only in fens. Since these habitats depend on groundwater inflows, an understanding of their geologic setting and hydrologic characteristics is necessary for successful management and protection schemes.

The Iowa fen study has led to a much better understanding of fen wetlands. Several papers have been published or are in press, including one on the geologic setting of Iowa fens (Fen Age and Development, abstract), one on the age and developmental history of fens in Iowa (Fen Evolution, abstract), and one on management issues related to fens. Other papers are being written which will detail water movement and water quality in Iowa fens. Also available in the Browse Area is a general article on fens (Fens), and the history of peat usage (Peat) and production (Peat Production) in Iowa, as well as a general article on (Wetlands). The Iowa State University Extension Office also has available three non-technical publications on fens. For information on these publications contact Extension at (515)294-4576.

The Geological Survey Bureau is just beginning a new wetland project to track the hydrology of a restored prairie pothole. Pothole restoration has been underway in Iowa for many years and many thousands of acres have been restored. However, there has been some concern that restoration has not been able to restore some functions of the wetland, particularly the sedge edge which is so valuable to many species. Few if any studies have been done which compare the hydrology of a natural pothole wetland to a restored site. This project will monitor surface and groundwater levels over time at two sites on a National Guard base in central Iowa. Concurrent studies will track vegetative and faunal use at the sites.