Mummau served as defensive coordinator for the Clarkson Golden Knights under head coach Bill Bergan for the last two seasons and helped the team secure a berth in the Liberty League Tournament in both years. While at Clarkson, he was charged with the oversight of the defensive side of the field, including midfielders, defensemen, and goalies. He oversaw player development, creation of game plans and scouting reports, as well as planning practice on a daily basis on the defensive end. Mummau was also heavily involved in recruiting, in addition to assisting Coach Bergan in the day-to-day operations of the Golden Knights program.

He was a four-year starter (2014-2017) on the Bryant University Lacrosse team under head coach Michael Pressler. Mummau was a three-time NEC All-Conference First-Team selection and was an NEC All-Rookie Team selection in 2014. In 2017, he captained the Bulldogs and earned USILA Scholar All-American honors.

He graduated from Bryant in 2017 with a degree in Biology and recently earned his master's degree from Clarkson in 2017 with a degree in Environmental Science and Engineering.