Salmon are great swimmers. They're born in rivers and lakes but they swim all the way to the ocean. They hang out for two to eight years and then return back home to lay eggs and die. One hundred years ago, millions of Puget Sound salmon made this trip, but now only about 10% of that amount do it. This means their habitat may be in trouble. Andy, Mason, and Marshall wonder: do more salmon thrive in the Dewatto River or the Union River?