Environmental activist Erin Brockovich, portrayed by Julia Roberts in a 2000 movie about her fight over the pollution of a California town, was arrested on suspicion of boating while intoxicated at Lake Mead near Las Vegas, authorities said Sunday.

Brockovich was arrested late Friday night after breath tests showed her blood-alcohol level was just over twice the legal limit of .08, said Edwin Lyngar, spokesman for the Nevada Department of Wildlife.

A game warden noticed she was struggling and needed assistance while trying to moor her motor boat at the Las Vegas Boat Harbor, he said. Brockovich had been out on the boat with a male companion but was alone when she tried to dock it.

"She was not sure how to maneuver the boat into the dock," Lyngar told The Associated Press. "It's a simple thing if you can think clearly. But if you add alcohol and unfamiliarity of the area, it can all cause serious problems."

Brockovich, 52, of Agoura Hills, Calif., was released from the Clark County Detention Center after posting $1,000 bail.

In a statement issued Sunday, she apologized for her actions but stressed that she did not operate the boat in open waters. She only moved the boat within its own slip, she said.

"At no time was the boat away from the dock and there was no public safety risk," Brockovich said. "That being said, 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 added.

Under Nevada law, a first-time offense of boating while intoxicated is a misdemeanor that draws fines from $1,000 to $2,000 but no jail time. Authorities were unsure whether it was Brockovich's first arrest on the charge.

Brockovich's efforts to sue Pacific Gas & Electric for polluting the water supply of a small Southern California town were adapted into a big-screen story, "Erin Brockovich," starring Roberts in the Oscar-winning title-role.

Last year, Brockovich was back on the big screen in the documentary "Last Call at the Oasis," which explores challenges related to the planet's dwindling and increasingly polluted water supply.