The area of Calmus Creek affected by the chalky material deposits was estimated to be 4.5 acres. Calmus Creek flows through Cerro Gordo County on into the Winnebago River. The first documentation of contamination was in 1984 and the creek was expected to recover by 2004 without additional releases. The natural resource injuries were the result of chalky solid materials being transported into the creek from adjacent cement plant areas. The chalky materials covered the creek substrate and created high pH conditions in the surface water.