Brockovich-Ellis, 52, issued a public apology after her arrest, said the Hollywood Reporter.
"I take drunk driving very seriously, this was clearly a big mistake, I know better and I am very sorry. After a day in the sun and with nothing to eat, it appears that a couple of drinks had a greater impact than I had realized," she said
Brockovich-Ellis was reportedly struggling with mooring her motor boat at the Las Vegas Boat Harbor. A breath test showed that her blood-alcohol level was just over twice the legal limit of .08 per cent, and she was subsequently arrested.
Brockovich-Ellis came to fame after landing a job as a legal assistant and helping to bring down a California power company accused of polluting a city's water supply.
The events were depicted beautifully in the film 'Erin Brockovich' which won Roberts the best actress Oscar.