Harmon finished with 129 yards and a score on 19 carries and completed eight of 17 passes for 112 yards and a touchdown.
“(We were) just getting jammed up,” Zimmer said. “Hennessey made plays, and we couldn’t do anything about it.”
Washington couldn’t extend its win streak to eight games, but followed a 5-6 run in 2011 to finish 8-4.
“I feel like we overcame a lot from last season,” Zimmer said. “It’s a tough break. Hennessey’s a good team. A great team.”
Hennessey will visit Vian, on Friday in the Class 2A state quarterfinal round.