SANTA CLARA, Calif. >> San Francisco 49ers defensive lineman Demarcus Dobbs was suspended Wednesday for a Week 1 game against Green Bay for a violation of the NFL’s substance abuse policy.

The 49ers, in announcing the penalty jointly with the NFL, say Dobbs will be eligible to return to the active roster on Sept. 9, a day after the reigning NFC champion Niners’ season opener at home against the Packers. He can still practice with the team, attend meetings and other activities.

On Wednesday afternoon, the team was holding meetings before an early evening practice. Dobbs wasn’t immediately available for comment, and the suspension was announced just after coach Jim Harbaugh addressed the media for the day.

“The San Francisco 49ers organization supports the NFL’s code of conduct policy and their recent decision regarding Demarcus,” general manager Trent Baalke said in a statement.

Dobbs ended last season on injured reserve with a right knee problem, missing the final three regular-season games after getting hurt against Miami on Dec. 9.

He was arrested Nov. 30 — his 25th birthday — for suspicion of driving under the influence and possession of marijuana. NFL spokesman Greg Aiello would not say whether the suspension stems from that arrest or a subsequent violation.

The California Highway Patrol said that Dobbs was involved in a single-car accident in which he hit a chain-link fence and a bush but didn’t sustain any injuries. Dobbs later expressed how sorry he was, and lucky, too.

Just more than a week after his own incident, Dallas Cowboys linebacker Jerry Brown died in a Dec. 8 accident in which defensive lineman teammate Josh Brent was the driver. Brent is charged with intoxication manslaughter.

“It was a wake-up call to me what happened to me,” Dobbs said at the time. “The thing that happened in Dallas, it makes me grateful that God was looking out for me. It could have been a lot worse in my situation.

“What happened in Dallas is unfortunate. It just goes to show what could have been. I’m grateful that I’m here and able to be on the team and go on and continue my life. That saddened me to hear that, but it made me count my blessings even more.”

The third-year pro out of Georgia, who signed as an undrafted free agent in July 2011, had three tackles in 12 games last year. He played primarily on special teams.

Harbaugh said Wednesday he had “a list of eight or nine guys” who wouldn’t make the trip with the team for Friday’s exhibition game at Kansas City but provided no further details such as names.