Environmentalist Brockovich had a blood-alcohol level that was more than twice the .08 legal limit, a Nevada Department of Wildlife representative said.
Roberts won the Best Actress Oscar in 2001 for portraying the dedicated and fiery activist Brockovich.
Add new fall shows to your watchlist
If Brockovich is convicted as a first-time misdemeanor offender of boating while intoxicated, faces a fine up to $2,000 but no jail time. She was released from the Clark County Detention Center on $1,000 bail.
She also appeared in last year's documentary Last Call at the Oasis, which focused on a dwindling and polluted water supply.