About a week ago, The New York Times published an article by my former colleague Anthony DePalma about what he called one of New York's "dirtiest environmental secrets."

The secret was that whenever there is a heavy rain in New York, the city's sewage system is overwhelmed and polluted water flows into the areas waterways. This recent storm also crippled the subway system, which was inundated with flood water.

When I saw Anthony's article [subscription required], I was transported back to the days too many years ago when I was a Times reporter and covered the rash of medical waste that started to appear on the beaches of Long Island. I was a metro desk correspondent for the Times on Long Island and newsworthy garbage of all kinds kept me byline in the paper. (The other major story of the day was the fight over the Shoreham Nuclear Power plant, but that's a story for another post.)

When I wrote about medical waste in the late 1980s, I remember being amazed to learn that very little rainfall could cause the sewers to overflow. Anthony's article reminded me that it was as little as a tenth of an inch of concentrated rainfall that cause millions of gallons of water mixed with untreated sewage to dump into the Hudson and East Rivers and New York Harbor. In a typical year, 27 billion – that's billion with a b! – gallons of sewage and polluted storm water flow into the water surrounding the city.

Disgusting, isn't it? And not unique to New York. The Times reported that approximately 800 American cities have the same problems. No wonder that NRDC's annual beach report recently found that pollution caused a record number of beach closings nationwide in 2006. The number of closings and advisory days at ocean, bay and Great Lakes beaches topped 25,000 – more than ever recorded in the survey's 17-year history.

The recent Times article quoted city officials describing efforts to build four massive holding tanks where the combined storm water and untreated sewage can be held until treatment plants can handle it. Two of these are completed and two more are under construction.

But are holding tanks the answer? I agree with the guy from Riverkeeper, a colleague organization, who told the Times that the answer ultimately lies in reducing runoff, not only building giant holding tanks. "Green roofs, parks systems, more trees – these kinds of things will at a minimum offset the impact of a big storm," the Riverkeeper's Basil Seggos said.

Plant a tree and keep the subways from flooding. Interesting idea.