Lewis, who announced Friday that he was leaving Colorado and transferring to Nebraska, was also charged with two counts of harassment.
The Denver Post first reported the news Sunday morning.
New Buffaloes coach Mike MacIntyre, who replaced Jon Embree after he was fired following a 1-11 season, issued a statement regarding both players.
"Jordan's exact involvement in this incident is still being investigated," MacIntyre said. "We continually stress the importance of appropriate behavior to our players and do not tolerate any detrimental conduct in our football program. Once all of the facts come to light, if Jordan is found responsible for any misconduct, he will be disciplined according to team rules."
Webb, who started the bulk of the games in 2012, suffered a torn ACL in spring but had hoped to return at some point in the 2013 season.
Lewis started 12 games last year and was expected to be the team's starting left guard in 2013. He missed all of spring recovering from shoulder surgery and did not discuss his transfer with MacIntyre, asking only to be released from his scholarship last month.
"As for Alex Lewis, as of Friday he was off of the team when he did a media interview and announced that he is transferring to Nebraska," MacIntyre said. "Since he is no longer a Colorado Buffalo, it will be up to Nebraska to decide what discipline he might face."
Last year, Webb threw for 1,434 yards with eight touchdowns and eight interceptions. Coming out of spring, it was thought that Nick Hirschman and Connor Wood would compete for the starting job in the fall. But Hirschman has since decided to transfer to Akron, paving the way for Wood to take over as starter -- though he'll be pressed by redshirt freshman Shane Dillon and incoming freshman Sefo Liufau.