Will somebody come clean about those soap-like bubbles in Malibu’s tiny Marie Canyon Creek?

A legal battle between an environmental crusader and Pepperdine University is raising questions about a frothy cascade of storm water that periodically spills over a beach lined with celebrity homes and into the Pacific Ocean.

Videographer Cary ONeal, who blogs as “Mr. Malibu,” insists that the runoff is tainted by a sewage treatment plant that serves the university and a housing tract next door, and that the school should be held to task for it.

Pepperdine officials dispute that and have gone to court to prevent ONeal’s accusation and home-made videos of the sudsy flow from going viral.

In a city that has long wrestled with the issue of polluted runoff, accusations of dumping are not taken lightly. Recently, the city agreed to pay $6.6 million to settle a lawsuit filed by two environmental groups that said officials were doing too little to prevent polluted storm-water from flowing into the sea.

The Pepperdine dispute is unique, however, in that it actually involves a sewer system and a wastewater treatment plant. Malibu formed its own government in 1991 for the specific purpose of preventing Los Angeles County from installing a sewer system, which residents thought would lead to unchecked development.

The matter seeped into public view on March 25 when ONeal posted a 30-second video titled “Pepperdine Recklessly Dumps Sewage on Malibu Beach” on his Facebook fan page. It showed images of the small Malibu Mesa Water Reclamation Facility and sudsy water gushing into the ocean at the bottom of Marie Canyon Creek.

Pepperdine quickly responded with a cease-and-desist order and a letter saying the Malibu Mesa treatment plant is operated by Los Angeles County, not the school. Pepperdine, the letter said, was unaware of any discharge of effluent. A short time later, ONeal’s fan page disappeared from Facebook.

ONeal replied with a second, longer video on YouTube. “Malibu, California, USA – Luxury Beach Homes of Adam Sandler, Tom Hanks, David Duchovny and Pink Under Siege,” began the four-minute tape. It included the earlier runoff footage and blamed Pepperdine for the Facebook ban.

Pepperdine shot back by telling ONeal that it planned to seek a temporary restraining order blocking him from “depicting the normal operations of culverts and storm drains and falsely suggesting they are depictions of Pepperdine’s dumping of sewage effluent” onto the beach.

On Wednesday, the university filed a lawsuit in Los Angeles County Superior Court alleging libel and “invasion of privacy by placing person in false light in public eye.”

Jerry Derloshon, Pepperdine’s senior director of public affairs, said the lawsuit was filed only after ONeal refused the university’s requests to remove the video and deleted comments that school officials had posted on his website rebutting the claims.

ONeal has since removed the videos from the Web.

Built in 1978 by Pepperdine and neighboring housing tract developer Alcoa, the small treatment plant is operated by the county Department of Public Works.

Under an agreement with the state’s Regional Water Quality Control Board, the treated effluent can be used for irrigating Pepperdine’s lawns. In emergencies, the plant can discharge surplus effluent into Marie Canyon Creek during the Nov. 1 to April 15 “wet season.”

But that hasn’t happened since about 2005, said Kerjon Lee, public affairs manager for the Public Works Department.

Lee declined to speculate on what might have caused the water to appear sudsy. He said that the county has constructed a $1.3-million filtration station next to Malibu Road to kill bacteria in the stream water but that the filters are bypassed during stormy weather.

Dr. Daniel Hillman, a retired orthopedic surgeon who has lived on the beach near the stream for 54 years, said signs around the mouth of Marie Canyon Creek warn swimmers of poor water quality.

“Before the treatment plant was built, the creek was dry most of the time. Now it runs almost 365 days a year,” Hillman. “Sometimes it stinks, sometimes it’s brown.”

ONeal, 56, of Point Dume, said he has lived all his life in Malibu. Growing up in the Malibu Colony, he remembers swimming as a boy in the Malibu Lagoon and hiking up Malibu Canyon to the Rindge Dam.

As a teenager, he surfed daily — until polluted water at a surf break called Old Joe’s left him with a facial staph infection.

“I had to take antibiotics for seven years,” ONeal said. “I ask myself why I didn’t start doing something to clean up the ocean back then.”

bob.pool@latimes.com