East Bay cities will speed sewer system improvements under an agreement announced Tuesday that is the latest in a decades-long drive to slow the flow of raw sewage into San Francisco Bay.

Several East Bay cities are served by a network of thousands of miles of aging sewer pipes -- many of them made of clay -- that are cracking so badly that in rainy weather millions of gallons of water infiltrate the pipes and overwhelm treatment plants, causing raw or partially treated sewage to overflow into the bay.

This season alone, nearly 125 million gallons of diluted sewage poured into the bay from overflow structures in Richmond and Oakland, regulators say.

"This is certainly one of the most significant areas of this kind of discharge of sewage in the nation," said Jared Blumenfeld, regional administrator for the U.S. Environmental Protection Agency. "The East Bay system is substantially worse than the kinds of spills you see in Marin or the Peninsula."

The order affects seven collection systems that feed into the East Bay Municipal Utility District's wastewater treatment plant. Those systems serve 650,000 customers in Oakland, Emeryville, Piedmont, Berkeley, Alameda, Albany and the Stege Sanitary District, which includes Kensington, El Cerrito and a portion of Richmond.


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Two years ago, regulators reached a similar agreement with East Bay Municipal Utility District to address leaking in its interceptor pipes, which collect sewage from the cities and carry it to the wastewater treatment plant.

Under the order filed Tuesday in U.S. District Court in San Francisco, the municipalities will do more monitoring, maintenance and reporting to better target the worst problems.

In the coming years, a more definitive agreement will be negotiated to end the spills, said Ben Horenstein, manager of environmental services for East Bay Municipal Utility District.

The EPA estimates that East Bay Municipal Utility District has spent $325 million, and the cities $335 million, to address the problem over the past 25 years.

The 2009 agreement with EBMUD increased its spending by about $5 million per year.

It is harder to determine the cost of the most recent order to the seven municipalities, but the largest -- Oakland -- has approved a series of three 16 percent rates hikes to cover costs in the agreement. The first of those hikes took effect Jan. 1, said Vitaly Troyan, Oakland's director of public works.

Troyan said Oakland has replaced about 25 percent of its sewer pipe in the past 20 years at a cost of $200 million. Those improvements cut in half rainwater infiltration, he said. In addition to rainwater infiltration, overflows are caused by roots and grease backups, Troyan said. The single easiest thing Oakland residents can do to reduce overflows is to put cooking grease into their yard waste bins instead of down the drain, he said.

In addition to the municipalities and the EPA, parties to the agreement including the U.S. Department of Justice, the State Water Resources Control Board and its San Francisco Bay region, and San Francisco Baykeeper, an environmental group.

Mike Taugher covers the environment. Contact him at 925-943-8257.