With challenging weather conditions during the final round, which included heavy rain early on followed by strong winds, every team finished over par in the last 18 holes of play.
It was the remarkable 14-under score in the first round on Monday that provided Oregon State with the cushion needed to maintain their lead and claim the championship.
Washington State finished runners-up with a total score of 9-over 861.
Prieto entered the final round, trailing Jackson Lake of Oregon State by one shot, as Lake had taken the 36-hole lead with a score of 5-under and rounds of 66-71.
Prieto shot a final round even par 71 that included four birdies and an equal number of bogeys against Lake's 2-over 73 to emerge as the winner by a shot.

