The U.S. Army Corps of Engineers is responsible for measuring and computing the diversion of Lake Michigan water of the diverted watershed. Measurements are presently taken at the Chicago Sanitary and Ship Canal (CSSC) near Lemont, Illinois. Beginning with the reversal of the flow of the Chicago River in 1900, the other Great Lakes states (Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin) have been concerned about the diversions of Lake Michigan water out of the basin. Their concern has led to litigation and a series of U.S. Supreme Court Decrees, which have regulated the diversion since 1925. In accordance with the U.S. Supreme Court Decree modified in 1980, and WRDA 1986, the Corps continues to execute the responsibilities of diversion accounting computations and diversion certification.