Last week, the U.S. Supreme Court declined to hear a lawsuit brought by Minnesota and four other Great Lakes states âÄî Wisconsin, Michigan, Ohio and New York âÄî to force the closure of the Chicago shipping canal that connects the lake system to the Mississippi River. Originally introduced into southern catfish ponds in the 1970s in a misguided effort to control algae, aggressive Asian carp have steadily moved northward. Once into Lake Michigan, the fish âÄî which can weigh upward of 50 pounds and are known to hit passing boats and passengers when leaping from the water âÄî have unimpeded access to Lake Superior and MinnesotaâÄôs 140 miles of shoreline. The fish outcompete native species, threatening the lakesâÄô $7 billion fishing industry by starving native salmon, trout and walleye. Once in Lake Superior, it is likely a matter of time before the carp spread to the stateâÄôs 10,000 famous lakes that anglers and boaters depend on. The Chicago canal, completed in 1900, still provides efficient transport of grain and coal to Chicago-area industries. Unfortunately, it has turned into a superhighway for invasive species, such as the notorious zebra mussel, which already has inundated lakes across the state. Temporary fixes and half-measures will not be enough to stop this problem. Electric fencing has not proven sufficient. The only permanent solution is to close the canal and restore the natural separation between the countryâÄôs two major freshwater systems. With the statesâÄô efforts halted by the Supreme Court, it is time for Congress to force this solution.