McDonogh sent coach Scott Ward out a winner.
The third-seeded Eagles won the Maryland Interscholastic Athletic Association water polo championship Friday night, edging defending champion and top-seeded Calvert Hall, 9-8, in Owings Mills thanks to a goal from senior Albert Schmickel with 39 seconds remaining.
Schmickel also had the tying goal, but Ward was the bigger story.
Ward is leaving his position after 14 seasons and three stints, but he won't officially inform the Eagles of his departure until Monday.
"I never told them," said Ward, whose team upset second-seeded Loyola Blakefield in the semifinals, 13-6. "I didn't want it to be about me. That's why. I will still teach and coach swimming here. I had spread myself kind of thin."
McDonogh became the first third seed to win the title since the league made water polo an official sport in 2000.
It didn't look like that would be the case.
Calvert Hall jumped out to a 4-1 lead in the first 3:33 as Pat Burke scored twice and David Warren and Tim McCown each added a goal during that span.
Ward called a time to settle his team down and it work. The Eagles closed the gap to 4-3 a little more than two minutes later.
Calvert Hall led 6-5 at halftime and by a goal twice in the fourth quarter before McDonogh finished with a flourish.
Schmickel scored with 1:54 remaining and then again 75 seconds later.
He finished with three goals. Tarik Lott also had three while Daniel Sweeney chipped in two and William Ginn added one.
Matt Rothman, McCown and Pat Burke had two goals each.
Calvert Hall coach Mark Rich seemed stunned at the loss.
"We know what it is like to be in one-goal games," he said. "Ninety-five percent of the time we come out on top. What McDonogh did was unbelievable. They stepped up big. "