Flakes of chromium rinsed off airplane parts. Silver residue washed down the drain in photographers' dark rooms. Bits of lead eroded from old plumbing. Every day, more than 300 pounds of toxic metals are flushed through Orange County's sewers and into the ocean.

But that's the bad news. The good news is that the metallic poisons pumped into the ocean off Huntington Beach through the county's sewer system have declined by 82% in the past 15 years--23% in the last year alone, sanitation officials report.

Throughout Southern California, officials are doing just as well in cleaning up the sewers, if not better. Los Angeles County has reduced by 93% the metals flowing into the ocean from its outfall pipe compared with 1976, while the city of Los Angeles eliminated 83%.

"It's rather striking to see what some municipalities were discharging in the '70s compared with today," said William Pierce, chief of compliance for the western office of the U.S. Environmental Protection Agency. "We've been making some rather substantial progress, and it is a result of a major initiative that took place throughout the state."

Most of the credit for the vast improvement goes to increasingly stringent federal and state clean-water laws, which require businesses to cleanse their industrial waste water before flushing it down the drain. Enforcing the laws are local pollution "cops" whose job includes pre-dawn visits to manholes to sample sewer water and catch illegal dumping.

"Industry is beginning to realize more and more that pollution prevention pays," said Blake Anderson, technical director of the Orange County Sanitation Districts, which operates the county's main waste water treatment system. "They're finding out they're either going to get hammered by us for dumping in the sewers or by other environmental agencies enforcing other laws."

At stake in the battle to clean up the waste water are the creatures that inhabit the ocean, especially those that thrive on the ocean bottom. If uncontrolled, toxic metals, such as lead and cadmium, can accumulate in sediments and contaminate the organisms that are a key link in the food chain.

Environmentalists say even the lower amounts of pollutants are too much because no one really knows how much pollution the ocean ecosystem can withstand. They urge a more thorough cleansing of the effluent, called secondary treatment, to remove even more contaminants.