After Helena Central closed, Donovan attended Class AA Helena High School, continuing to excel in track and field at the Class AA level, winning the shot put and discus competitions at the state meet in both his junior and senior seasons.
[2] Donovan also led Helena to the state championship basketball final as a junior and senior, losing to Kalispell in 1970 and winning against Billings West in 1971.
Donovan was selected by the Dallas Cowboys in the fourth round of the 1975 NFL draft as a defensive end.
After being a reserve during his first two seasons, he took over the right tackle job in 1977 when Rayfield Wright went down with an injury, helping the team win Super Bowl XII.
Donovan became one of the top offensive tackles in the NFL during the late 1970s and early 1980s and together with Herb Scott formed one of the best left-side tandems in the league.
He remains one of just five offensive tackles in club history to make at least four Pro Bowls, joining Rayfield Wright (six), Flozell Adams (five), Erik Williams (four) and Tyron Smith (four).