Josh Gross tweets:

CSAC executive director George Dodd says steroid in Sonnen's system not natural substance.

Chael Sonnen tested for "well above normal levels of testosterone," according to CSAC executive director George Dodd. More coming on SI.com.

George Dodd also spoke with Sherdog:

"I have it but I haven’t really reviewed it yet, it is a steroid substance," said Dodd.

Lance Pugmire of the Los Angeles Times quoted Dodd as saying that the test came back positive due to the presence of a "natural steroid." The commission chief contradicted the report.

"No," said the Executive Officer. "I don’t believe it is a natural steroid."

Sonnen has 30 days to respond to the notice and lodge an appeal of his $2,500 fine and year-long suspension.

MMA Junkie has more:

The timing of the positive test could scratch the rematch unless Sonnen gets an appeal and resolution before the year's end.

"We always say you want to make [the appeal] at the next commission meeting (from the notice)," Dodd said. "The next [meeting] after that probably won't be until the following year, and from what I understand, he has a rematch with Anderson Silva possibly in February. He'll probably be maintaining the suspension unless he gets on the agenda next time."

Josh Gross adds this intriguing detail at Sports Illustrated:

Sonnen, 33, of West Lind, Ore., was apparently concerned enough about the possibility that he would render a positive test that he told CSAC executive director George Dodd he used an illegal performance enhancing drug leading up to the biggest fight of his life.
..
"He only indicated that he was taking it but he never indicated why," Dodd said of a conversation he and Sonnen shared during drug testing conducted by the state a day prior to the fight.

Sonnen "just let me know he was taking [something] and that's when I called over an inspector to get it documented. But when you do take it you still have to show a medical reason."
...
Though Sonnen mentioned using an illegal substance, the veteran mixed martial artist failed to note it on a pre-fight questionnaire with commission doctors or provide documentation about the use of testosterone in a medical context, according to Dodd.

More Bloody Elbow coverage of Chael Sonnen’s positive test result:

• Dana White and UFC Cannot Abandon Commissions for Better Drug Testing
• It's Time for the UFC to Step Up on Drug Testing
• Chael Sonnen Tests Positive for a "Natural Steroid"
• What Will the UFC Do About Chael Sonnen's Failed Drug Test?
• Chael Sonnen Was Even More Like a Pro Wrestler Than We Thought
• Chael Sonnen Fails His UFC 117 Drug Test, Positive for PEDs