SACRAMENTO, Calif. - Prosecutors said Monday they will not file criminal charges in the death of a 28-year-old woman who participated in a radio station's water-drinking contest.

The district attorney's office said the behaviour of staff at station KDND-FM did not rise to the level of criminal activity.

"There were no observable indications or symptoms that Jennifer Strange was experiencing a serious medical emergency which would have required station employees to seek or administer medical aid to her,'' the district attorney's office said in a statement.

Strange died Jan. 12 after taking part in an on-air contest to see which contestant could drink the most water without having to go to the restroom. The coroner's office ruled that Strange died of water intoxication.

At one point during the contest, a listener who identified herself as a nurse called "The Morning Rave'' program to warn the disc jockeys that the stunt could be fatal, according to an audio tape of the broadcast.

"Yeah, we're aware of that,'' one of the DJs responded.

Another DJ laughed: "Yeah, they signed releases, so we're not responsible. We're OK.''

Strange's family has filed a wrongful death lawsuit against the station, which fired 10 employees following the death.