In the day's opening women's 6k race, Stanford's Kathy Kroeger (far left, with Oregon's Alexi Pappas, Annie LeBlanc, and Washington's Megan Goethals/photo by Paul Merca), who stayed off the early pace, rallied in the last kilometer to take out a four-second victory over Oregon's Jordan Hasay, 20:06 to 20:10.
Oregon placed two other runners in the top five, with two other runners the top twenty to clinch a 47-69 victory over the Arizona Wildcats.
Stanford finished third with 82, just ahead of the Huskies in fourth at 92 points.
The University of Washington's Megan Goethals, running in her season debut, finished twelfth in 20:37, followed closely by Lindsay Flanagan in 14th at 20:37, with Justine Johnson one second behind in 15th.
Liberty Miller was 25th in 21:04, with defending Pac-12 champ Katie Flood, who had been struggling in the team's last race in Madison, Wisconsin, was 26th in 21:05 to round out the Husky scorers.
For Washington State, Caroline Austin led the Cougars to a 12th place finish with a 33rd place finish in 21:19.
Ruby Roberts was 53rd in 21:55, Emily Dwyer was 78th in 22:32, Courtney Zalud was 94th in 23:30, and Kiah Condos rounded out the scorers for Washington State in 96th.
Among notable Washington preps, Bellingham's Becca Friday was 48th for Oregon in 21:49.
In the men's 8k championship, Arizona's Lawi Lalang and Stephen Sambu pulled away from Oregon's Trevor Dunbar and Parker Stinson on the final lap to go 1-2 in a time of 22:49 to 22:50.
Dunbar was third in 23:28, with Stinson fourth in the same time.
Colorado put all seven runners in the top 18, led by Blake Theroux's eight place finish to successfully defend their Pac-12 championship with a score of 49 points to outdistance runner-up Stanford, who scored 82 points.
Oregon was third with 105 points, followed by Arizona State at 109, and UCLA at 113.
Washington was sixth at 119, while the Washington State Cougars were eighth at 200 points.
The Cougs were without the services of senior leader Andrew Kimpel, who was battling a hamstring problem, and was held out of the meet by WSU coach Tim Riley.
For the Huskies, Joey Bywater was first across the line in 16th at 23:58, followed by Tyler King in 22nd at 24:12. Aaron Nelson was 25th in 24:15, with Rob Webster Jr 27th in 24:17, and Aaron Beattie in 33rd at 24:23.
Washington State's Lee George was first across the line in 24th at 24:14, followed by Andrew Gonzales in 34th at 24:24.
Drew Jordan was 43rd in 24:37, with Todd Wakefield 49th at 24:53, and Forrest Shaffer 69th at 25;38.
Among significant Washington preps in the race, Gig Harbor's Miles Unterreiner of Stanford was 20th in 24:10.
Many of the schools who were in Santa Clarita will be in Seattle for the NCAA West Regionals on November 9th at Jefferson Park Golf Course, with berths to the national championships in Louisville, Kentucky on the line.