It is estimated that Indiana has already lost more than 80% of its original, native wetlands, and concerns have been expressed that some fraction, and perhaps even a sizable fraction, of these losses can be historically linked to highway construction associated with INDOT-related activities. These wetlands are important for several reasons, in that they help keep ground water and surface water clean, serve as reservoirs for floodwaters, help recharge groundwater, provide habitats for many species of animals, and serve as recreational areas. This underlying concern behind this accusation, therefore, is that the construction of state and federal roads historically carried out by INDOT has adversely affected wetlands quantitatively and qualitatively. Whether the accusation of a negative impact quantitatively is properly placed is the purpose of this research.

Aspects of wetlands that were examined include the extent of lands that were potentially historic wetlands, the relationship between these and the wetlands that currently exist within the state of Indiana, the relationship between road proximity and the prevalence of wetlands, and the relationship between farming intensity and wetlands and forest cover and wetlands. This research, however, did not attempt to determine any qualitative effects of road construction and proximity of roads in relation to wetland damage and/or loss.

This research effort was carried out primarily with the use of geographic information systems (GIS) using map data derived from a variety of sources, including: 1) the USDA National Forest Service Inventory Analysis (FIA); 2) the U.S. Dept. of Interior U.S. Fish and Wildlife Service National Wetlands Inventory (NWI); 3) the U.S. Dept. of Agriculture National Resource Conservation Service (NRCS) soils data; 4) the U.S. Department of Agriculture 1007 Census of Agriculture; and 5) Purdue University.

Report Number



wetland, loss, land, highway, construction, GIS, SPR-2205

SPR Number


Publisher Place

West Lafayette, IN

Date of this Version