Applying geospatial tools to assess the agricultural value of Lower Illinois River floodplain levee districts

• Assessment of agricultural value of floodplain levee districts.
• Improved methodology to assess potential restoration costs and benefits of agricultural land.
• No direct relationship between levee protection level and agricultural value.
• Previous estimates of per hectare wetland benefits outweigh the agricultural benefits currently provided along the Lower Illinois River.
• Multiple districts with low agricultural profit values can be analyzed further in floodplain reconnection studies.

During the 1920’s, Illinois River levees became increasingly difficult for private landowners and the state to maintain as commodity prices fell and flood levels increased. However, the 1928 U.S. Flood Control act shifted a substantial portion of the burden of flood mitigation from local landowners to the federal government, preventing the dissolution of levee districts. While these levee systems have facilitated floodplain agricultural production and development for the last century, disconnecting the river from its floodplain has led to concerns about the negative impacts of levees on the physical and biological systems of the Illinois River Valley. Recent studies have emphasized approaches that would result in setting back or removing levees in order to naturalize portions of large river-floodplain systems, including the Illinois. The costs and benefits of such projects along the Illinois have shown potential restoration benefits may outweigh potential costs, but these studies have not demonstrated the specific levee districts which have the highest reconnection potential from an economic standpoint. This study uses geospatial methods to fill this gap by assessing the National Commodity Crops Productivity Index (NCCPI) soil values and agricultural production and profit values for corn and soybeans in 32 individual levee districts along a 235-km segment of the Lower Illinois River. In general, soil productivity index values were lower for Illinois River levee districts compared to the county averages in which the districts are located. Over the five-year study period from 2010 to 2014, the total agricultural profits in the levee districts ranged from $18–61 million. Several levee districts have relatively low per hectare agricultural values when compared to the value of wetland benefits, indicating these protected floodplain areas may be more suitable for reconnection.