Sheriff's Lt. Matt Ohnemus told City News Service that Gregory Belda was in a boat that lost control and was struck by another boat. Belda died at the scene.
The crash occurred Saturday on a lake in Frank G. Bonelli Regional Park in San Dimas. The boats were doing a practice run between heats.
In 2011, three people were killed when their Sea-Doo personal watercraft collided with a boat in the same lake.