Pollution sleuth on case

For years, Martin County health officials have blamed birds, raccoons and pets when evidence of sewage pollution shows up in local waters, particularly after heavy rains. But the suggestion that bacteria from septic tanks flushes into the rivers as runoff never has been investigated -- until now.

John Polley, Martin utilities director, will ask Harbor Branch Oceanographic Institution scientist Brian Lapointe to duplicate in Stuart the investigations he has performed in the Keys and the Jupiter-Tequesta area. Mr. Lapointe will try to discover the source for consistently high fecal coliform counts near the Roosevelt Bridge. The counts are evidence of human or animal waste, which can cause eye and ear infections or intestinal illness in humans, and can lead to harmful algae blooms.

The Martin County Health Department reported levels of 2,688 organisms per 100 milliliters of water early last week and about half that number two days later -- far exceeding the state limit of 399. The health department had warned people to stay out of the river near the bridge for two weeks this month when levels were high.

Mr. Lapointe will analyze water samples from nearby subdivisions and compare them to samples from aquatic plants in the river to determine whether septic tanks are the source. He also analyzes samples of sediment from the river bottom for evidence of sewage pollution and will sample wider areas of the river for comparison. Similar sleuthing allowed Jonathan Dickinson State Park in Hobe Sound to reopen a swimming hole that had been closed for years, when pollution was traced not just to a cattle operation but to septic tanks. Among other things, nearby communities agreed to limit the number of septic tanks.

Boaters who anchor out near the Roosevelt Bridge have been blamed for spikes in fecal coliform levels. A spokesman for the Florida Department of Environmental Protection, however, said levels would be much higher if sewage were dumped from boats. A spill from a sewage treatment plant could send the count into the millions.

Mr. Lapointe's research, linking human waste to runaway blooms of underwater weeds that cover the ocean floor, has gained worldwide attention. Wastewater, in runoff or leaching onto ocean reefs after municipalities pump it deep underground, has become a coastal problem around the globe. Bird droppings are an interesting theory, but it's time to find the real pollution source near the bridge and stop it.