Commissioner Larry Scott officially announced Thursday how the Pac-12 would be divided for the 2011 season, laying rest to weeks of speculation.

The decision hinged on the debate over how the conference would be split for the football season, as the 12-team group now warranted two separate divisions.

Scott said that there would be North and South divisions, news that, among other things, meant the California schools will be split up evenly.

The South Division will be composed of USC, UCLA, Arizona, Arizona State, Colorado and Utah — the last two being the new expansion teams in the conference. Stanford, California, Oregon, Oregon State, Washington and Washington State comprise the North Division.

The winner of each division will then play in the Pac-12 Championship game, which will take place in December on the home field of the school with the best conference record. Scott said Thursday that it was decided to pass up the potential revenue of playing the game at a large, neutral site stadium, saying it was more important to reward the fans and ensure a strong collegiate atmosphere.

“If you had told me a year ago that this conference would have expanded by two, that we’d have a championship football game, and have the level of commitment and support throughout this conference, and the level of optimism, I’d have been thrilled,” Scott said in the press conference.

The Trojans will be able to play these rivalry games every year, under a clause that locks both USC and UCLA into games against both Stanford and Cal, preserving the tradition of the historic California rivalries.

USC Athletic Director Pat Haden had previously expressed disappointment that the California schools could be split up into separate divisions, citing negative alumni reaction toward the split. He emphasized the need to play Stanford and Cal every year.

He said Thursday, however, that he was pleased with the announcement.

“At the end of the day, the presidents did a great job because they were able to preserve the rivalries — not only from USC’s perspective, as I understand it, but Oregon, Oregon State, Washington, Washington State and all those schools,” Haden said in a statement.

Each team will play five divisional games and four interdivisional games. The Oregon and Washington schools will play in Los Angeles every other year, instead of annually as they do now.

The issue of how often teams would play in California was among the most hotly contested debate among conference presidents and athletic directors. The idea of a “zipper” plan would have split up all rivalry schools into two divisions, meaning USC and UCLA would be separated, as well as Stanford and Cal, Oregon and Oregon State.

The agreement of equal television revenue sharing among all teams was unanimous, meaning all revenue made from television will be split equally between the 12 schools. However, if media revenue falls under $170 million in any given year, USC and UCLA will receive an extra $2 million each.

Scott called the unanimous decision for equal revenue sharing a harmonious and “very strong statement.”

“I am just really pleased with the way everyone came together and realized we’re building an enterprise that’s about to scale in a way these schools have never been part of,” Scott said.

Haden said he was also happy with the decision to share television revenue.

“The pie will get bigger,” he said. “Everybody’s going to benefit.”

The changes will be in effect starting next year, after Colorado was able to negotiate a deal securing an early release from its Big 12 Conference agreement.

There will be no divisions for any other sports. Men’s and women’s basketball will play 18 conference games, including home-and-homes against traditional rivals.