AJ Armstrong shot a 6-under 65 to help Washington State make up a seven-shot deficit entering the final round to win the Itani Quality Homes Collegiate at Palouse Ridge Golf Course in Pullman.
The Cougars finished 33-under 819 and secured a one-stroke advantage over runner-up Boise State. Armstrong finished tied for fifth overall individually at 205.
Idaho placed ninth in the 11-team field at 13-over 865. The top Vandal was Adam Veenstra at 1-under 212, tied for 19th.
Alivia Brown shot 4-over 22 and placed tied for 25th and Washington State took 16th (40-over 904) out of the 18-team field in the Dick McGuire Invitational at The Championship Golf Course in Albuquerque, New Mexico.
Alexa Clark tied for eighth at 4-over 220 and Eastern Washington finished in sixth place out of the eight-team field (39-over 903) at the Battle at Old Works Invitational in Anaconda, Montana.