Iowa Department of Transportation. (2019). Alt2 Levee Bridges: Iowa. State of Iowa. http://public-iowadot.opendata.arcgis.com/datasets/16e18d2341584dba81af7ac9a4910107_2

Available from: https://geo.btaa.org/catalog/16e18d2341584dba81af7ac9a4910107_2