"Historically there's been a proven health risk from swimming in those polluted waters," said Mark Gold, president of Heal The Bay.
Gold says that is why the Los Angeles Regional Water Quality Control Board wants to ban new septic systems in large swaths of Malibu and phase out existing septic systems within five years.
The moratorium essentially forces Malibu to build a central sewage treatment plant. That proposal packed a Metropolitan Water District boardroom Thursday, with Malibu residents, city officials and environmental groups.
"Trying to ban septic systems is not necessarily the right or fiscally sound approach to use," said Malibu City Manager Jim Thorsen.
Thorsen says the city is already planning to build a wastewater treatment plant that could go online in April 2015. But the facility would serve a much smaller area than what the Water Board is proposing.
The city says that septic systems work well in many parts of Malibu, and that the smaller, more targeted treatment plant could take care of trouble spots like the business district, and do so at a more reasonable cost to residents and businesses.
"Overall, the price tag for the Regional Board prohibition is over $50 million," said Thorsen. "Our price tag is about 40 percent less than that."
But environmentalists say Malibu has made countless promises to fix its pollution problems, with little or no progress.
A government-mandated septic ban, they say, is the best option.
"After 18 years of waiting for Malibu to do the right thing on wastewater, it needs to be legally enforceable," said Gold.
So contentious is this septic ban that the list of people who registered to address the Water Board stretched some nine hours long.