Jan 18, 2008 — The St. Lawrence Seaway has introduced a new way to keep invasive species from sneaking into the St. Lawrence River and the Great Lakes. Under a proposed rule announced yesterday [Wednesday], oceangoing ships would have to flush their ballast tanks with salt water at least 200 miles from the North American shore. At least 185 exotic species have been found in the lakes. Many were scooped into ship ballast tanks in foreign ports, hauled across the Atlantic and dumped into the Great Lakes when the ships emptied their ballast tanks to take on cargo. St. Lawrence Seaway Administrator Terry Johnson describes the proposed rule as an interim measure while a tougher bill works its way through Congress. Johnson told David Sommerstein it was time for the Seaway to act.