GOLDEN, Colo. — A woman who told police she wanted to be a “cool mom” pleaded guilty to sexual assault charges Monday for having sex with high school boys at parties where authorities said she supplied drugs and alcohol.

Silvia Johnson, 40, pleaded guilty to two misdemeanor counts of sexual assault and nine felony counts of contributing to the delinquency of a minor. As part of a plea agreement, prosecutors dropped two counts of distribution of methamphetamine.

“She described herself as a `cool mom,'” Detective R.J. Vander Veen wrote in the affidavit. He said Johnson told investigators “she was never popular with classmates in high school and now began `feeling like one of the group.'”

Prosecutors did not recommend a sentence, but each sexual assault count carries up to two years in prison, and each count of contributing to the delinquency of a minor carries up to six years, district attorney’s spokeswoman Pam Russell said.

Johnson, who is free on bail, held parties for the boys almost weekly between October 2003 and October 2004, authorities said. She was accused of providing drugs and alcohol to eight boys and having sex with five of them.

Police said the investigation began after one of the boys told his mother about the encounters, and she reported it to authorities.