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About the Wet Weather Issue

The Pittsburgh region's frequent rainfall brings an underground, out-of-sight problem into clear view. As little as one-tenth of an inch of rain—an average Pittsburgh rainfall is one-quarter inch—can cause raw sewage to overflow into our rivers and streams. Melting snow can cause the same effect.

During dry weather, the sewage collection system, which transports wastewater from thousands of homes to the wastewater treatment plant, operates effectively.

However, when it rains or snow melts, extra stormwater gets into the sewage collection system through direct connections or through leaky, cracked pipes. This extra volume of water overloads the sewage collection system pipes and raw sewage overflows at hundreds of locations before it reaches the treatment plant. Untreated sewage streams into waterways, overflows from manholes or backs up into homeowners' basements.

And the effects of wet weather can last for days. During the recreational boating season, May 15-September 30, Allegheny County issues river advisories to warn individuals using the rivers to limit water contact when sewage overflows have likely contaminated the water with bacteria and viruses. Each time a river advisory is issued, it could last for several days after a rainfall.

Since the program began in 1995, river advisories issued by the Allegheny County Health Department have been in effect for nearly 50% (70 days) of each recreational season.

Sewage overflows present a public health risk. While exposure to disease-causing organisms, such as giardia or cryptosporidium, are not considered fatal for a healthy adult, they can be deadly for those with weaker immune systems, the elderly and small children. In addition, Pittsburgh's three rivers serve as the main source of drinking water for 90% of Allegheny County residents. While the public water systems do an excellent job of purifying water before sending it to homes, source protection is the cheapest and most effective way to ensure drinking water quality.

Fixing the problem is going to require a substantial long-term investment. Some estimates for the cost of rehabilitating the sewage collection and treatment system total up to $3 billion. State and federal support may be available to help offset a portion of the bill, but municipalities must share resources and work cooperatively across geographic boundaries in order to significantly trim the total bill for ratepayers who will have to bear sewer rate increases in the coming years.

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