He often jokes that he has similarities with Sheldon from “The Big Bang Theory” but instead of talking enthusiastically about theoretical string theory and trains, Mark Nelson, Plan Formulator/Project Manager in the Omaha District Planning Branch, loves hydrology and weather. As Mark prepares to retire after almost 29 years with the Corps, a look back at his career path shows just how he was able to work on those things he loved to do while adding value to the Nation.