Because this traditionally agricultural state's most valuable resource has been its topsoil, Iowa's conservation measures beginning in the 1930s were directed toward preventing soil erosion and preserving watershed runoff. In the 1980s and 1990s, Iowans were particularly concerned with improving air quality, preventing chemical pollution, and preserving water supplies. In 1997, wetlands covered 12% of Iowa. The Wetlands Reserve Program of the 1990 Food, Agriculture, Conservation and Trade Act was created to reclaim some of the state's lost wetlands.
On 1 July 1983, the Department of Water, Air and Waste Management came into operation, with responsibility for environmental functions formerly exercised by separate state agencies. Functions of the new department include regulating operation of the state's 2,900 public water supply systems, overseeing nearly 1,200 municipal and industrial wastewater treatment plants, inspecting dams, and establishing chemical and bacterial standards to protect the quality of lakes. The department also enforces laws prohibiting open dumping of solid wastes, regulates the construction and operation of 140 solid waste disposal projects, and monitors the handling of hazardous wastes. It also establishes standards for air quality and regulates the emission of air pollutants from more than 600 industries and utilities.
In 2003, Iowa had 172 hazardous waste sites listed in the Environmental Protection Agency's database, 13 of which were on the National Priorities List. In 2001, Iowa received $52,181,000 in federal grants from the Environmental Protection Agency; EPA expenditures for procurement contracts in Iowa that year amounted to $7,000.