Visits to emergency departments and calls to the West Virginia Poison Center related to the Elk River chemical spill, West Virginia, January 9-23, 2014. Samples of treated potable water or finished water refer to water that has completed all treatment processes at a water treatment plant and is ready to be delivered to consumers. Abbreviations: ED, emergency department; MCHM, 4-methylcyclohexanemethanol; PC, poison center; PPM, parts per million; WVAWC, West Virginia American Water Company.