AU GRES, Mich. (AP) - Small levels of toxic flourochemicals have been found in a Lake Huron drinking water supply system that serves more than 260,000 people in dozens of Michigan communities. MLive.com reports that the Michigan Department of Environmental Quality disclosed the discovery of per- and polyfluoroalkyl substances in the Saginaw-Midland Municipal Water Supply Corporation system on Wednesday. The system draws water from two points near Au Gres. The concentrations are below the Environmental Protection Agency's health advisory level. Exposure to the chemicals has been linked to certain cancers, thyroid disorders, elevated cholesterol and other diseases. The department didn't identify a source for the chemicals, but recommended that local officials begin considering treatment options. The department says more than 50 communities in seven counties take water from the system, including Midland, Saginaw and Bay City. --- Information from: The Grand Rapids Press:MLive.com, http://www.mlive.com