It is estimated that before the 1750s, Iowa had around 2.3 million acres of wetlands. Today, Iowa has about 35,000 acres, with over 98 percent of the original wetlands converted to other uses—primarily agricultural production.
Herriges, Joseph A. Sr. and Kling, Catherine L.
"Iowa’s Wetlands: Who Will Pay for Preservation?,"
Iowa Ag Review: Vol. 6
, Article 3.
Available at: http://lib.dr.iastate.edu/iowaagreview/vol6/iss3/3