The Ducks placed three runners in the top five to win their first women's title since 1995, and the eighth in school history. Oregon won with 47 points, followed by No. 5 Arizona with 69, No. 4 Stanford with 82, No. 6 Washington with 92, No. 21 Colorado with 124 and No. 24 UCLA with 172.
"Our women did an outstanding job today in the toughest conference meet in the country," said head coach Robert Johnson. "They were strong from the start.
"It's very exciting to be able to bring our first Pac-12 women's cross country title back to Eugene. This was one of the few accomplishments that had eluded us in the new era at Oregon, so to speak, so this is a pretty big thing to check off the list."
Hasay added to her impressive Pac-12 resume with Saturday's runner-up finish in 20:10. The senior from Arroyo Grande, Calif., won this race as a sophomore in 2010 and was third a year ago.
Alexi Pappas, a senior transfer from Dartmouth, was fourth in 20:11, while freshman Allie Woodward was fifth in 20:16. The Ducks also counted freshman Annie Leblanc's 17th-place showing in 20:42 and senior Sarah Penney's 19th-place finish in 20:47. For good measure, Oregon also had senior Katie Conlon 23rd in 20:58 and freshman Abbey Leonardi 24th in 21:03.
Stanford's Kathy Kroeger was the individual winner in 20:06.
"All the credit goes to Coach Maurica Powell and our student-athletes," said Johnson. "They did a great job with the race plan and coming together as a group.
"Jordan and Alexi did exactly what we expected, but there were a lot of other runners who stepped up," said Johnson. "Allie Woodward ran up front most of the race and Sarah Penney was really tough today too. Placing seven runners in the top 25 is a very impressive accomplishment."
Oregon set the tone from the opening gun and never trailed. In the first third of the race, Woodward and Hasay and tucked in with the lead pack as the Ducks led with 28 points followed by Stanford with 71.
At the midway point, Woodward and Elvin Kibet of Arizona took a big lead on the field. More importantly, Oregon had seven runners in the top 15 to lead with 49 points with Arizona and Stanford standing at 75.
Things started to tighten over the final third. At the final split, the Ducks were standing on 50 points, followed by Arizona with 65, before Oregon put on a final push to win by 22.
Meanwhile for the men, Trevor Dunbar and Parker Stinson paced the Ducks to a third-place finish by taking third and fourth, respectively. Dunbar, the senior from Kodiak, Alaska, and Stinson, a junior from Austin, Texas, both timed 23:28.
"The men did exactly what they needed to do today to keep moving toward the NCAA Championships," said Johnson. "Trevor and Parker were right there up front the entire race and we also had some younger runners step up for us today."
Second-ranked Colorado successfully defended its Pac-12 title with 49 points. No. 3 Stanford was second with 82, followed by Oregon with 105, Arizona State with 105 and No. 15 UCLA with 113.
Oregon also counted a 31st place finish from freshman Matthew Melancon. The Eugene, Ore., native finished in 24:19. Additionally, the men had a 32nd place finish from sophomore Ryan Pickering in 24:22 and a 39th place showing from sophomore Cole Watson. The Rogue River, Ore., runner clocked 25:03.
Arizona's Lawi Lalang won the individual title in 22:49 with his teammate Stephen Sambu second in 22:50.