It was drizzling lightly in late October when the midnight shift started at the Owls Head Water Pollution Control Plant, where much of Brooklyn’s sewage is treated.
A few miles away, people were walking home without umbrellas from late dinners. But at Owls Head, a swimming pool’s worth of sewage and wastewater was soon rushing in every second. Warning horns began to blare. A little after 1 a.m., with a harder rain falling, Owls Head reached its capacity and workers started shutting the intake gates.
That caused a rising tide throughout Brooklyn’s sewers, and untreated feces and industrial waste started spilling from emergency relief valves into the Upper New York Bay and Gowanus Canal.
“It happens anytime you get a hard rainfall,” said Bob Connaughton, one the plant’s engineers. “Sometimes all it takes is 20 minutes of rain, and you’ve got overflows across Brooklyn.”
One goal of the Clean Water Act of 1972 was to upgrade the nation’s sewer systems, many of them built more than a century ago, to handle growing populations and increasing runoff of rainwater and waste. During the 1970s and 1980s, Congress distributed more than $60 billion to cities to make sure that what goes into toilets, industrial drains and street grates would not endanger human health.
http://www.nytimes.com/2009/11/23/us/23sewer.html?th&emc=th