Lake Superior tops the world’s largest freshwater ecosystem as well as the longest deep-draft inland waterway, extending from Duluth, Minnesota, to the St. Lawrence Seaway and the Atlantic Ocean. Roughly 10,000 cargo ships pass through the Soo Locks every year. When it comes to protecting the Great Lakes from invasive species, monitoring the ballast water on these cargo ships is key. In this episode of the Lake Superior Podcast, Walt Lindala and Frida Waara talk with Phyllis Green, former Superintendent at Isle Royale National Park as well as board member of the National Parks of Lake Superior Foundation, about ballast water and what is being done on both US and Canadian shores to protect Lake Superior.