Fretz began attending Clarkson University in he fall of 1981 and quickly became a mainstay on the blueline. He would lead the defensive corps in scoring in three of his four seasons with the Golden Knights and help the team post three 20+ win seasons in his time. Prior to his junior season, Fretz joined Team Canada in their run up to the 1984 Winter Olympics but was not retained for the competition. He did, however, help the team win the 1984 Spengler Cup, the first for Canada in the 58 years of the series.