On April 23, 2004, an explosion occurred at the Formosa Plastics Corporation plant in Illiopolis, located between Springfield and Decatur along I-72. Illinois EPA’s Emergency Response Unit staff were on site before midnight and began monitoring the air around the plant and in the community. During the weekend and the next week, other Illinois EPA staff worked with the Village of Illiopolis’ public water supply operator to test and insure the safety of the drinking water supply. Additional sampling was done along an unnamed creek just south of the site property, which continues east to the Long Point Slough and the Sangamon River. Since then, Illinois EPA has determined that a long-term presence at the site is needed in the form of oversight regarding site investigation and proper cleanup of contamination.