The Elizabeth Township Sanitary Authority, which illegally has allowed millions of gallons of raw sewage to flow into the lower Youghiogheny River during the past five months, has been ordered to reduce and eventually stop the overflows.

By Feb. 1, the authority must staff its Buena Vista treatment plant 24 hours a day, determine whether all plant equipment is operating properly, and begin manually operating raw-sewage pumps to maximize flow and treatment, according to an order issued yesterday by the Allegheny County Health Department.

The authority also must submit to the Health Department by March 20 a plan and schedule for the complete elimination of the sewage overflows, which continue to occur on a daily basis.

Part of the problem is that pipes connecting aeration and clarification tanks within the plant are too small to handle the flow of sewage. That prevents the plant from operating at full capacity, according to the state Department of Environmental Protection, which is working with the Health Department in the ongoing investigation.

Sewage overflows into the Youghiogheny and several tributary streams have occurred on 73 days since Aug. 19 and every day since Nov. 25.

Such overflows are in violation of the federal Clean Water Act, Pennsylvania's Clean Streams Law and the county's sewage-management regulations.

"We don't understand how someone would not know there is a problem," said DEP spokeswoman Helen Humphreys.

The treatment plant and the township's separate sanitary sewer system were built in the early 1960s. The treatment plant, which originally had a capacity of 890,000 gallons a day, was upgraded several times, most recently in the late 1990s, and now has a maximum capacity of 2.3 million gallons a day.

The plant's average daily capacity is 1.4 million gallons, but Veolia Water North America Operating Services, a French-owned company hired to operate the facility, reported that it has been treating less than 1 million gallons a day, even while overflows have occurred.

Although the largest overflow was 6.3 million gallons Dec. 16, eight of the 73 days had overflows of less than 500,000 gallons, an amount that could have been treated if the plant had been operating at its listed average capacity. On 22 days, the overflow was less than 1.4 million gallons, levels that could have been treated if the plant was operating at its listed maximum capacity.

County Health Department spokesman Guillermo Cole said penalties and fines for those violations are coming.

"This order is aimed at bringing relief in the short term," he said. "We will be following up with a more comprehensive order to deal with the situation in the long term."

The authority can appeal the order.

Neither Bill McKeever, vice president of Senate Engineering, the engineering firm employed by the sanitary authority, nor John Pecora, the treatment plant supervisor, could be reached yesterday. Robert Similo, authority chairman, also could not be reached.

The overflows date to at least the summer of 2006, when a fisherman on the Yough reported seeing raw sewage along the river bank near the treatment plant's discharge pipe. The sanitary authority was ordered to put in a flow meter to measure the untreated sewage, but didn't do so until last August.

Overflows were measured during the last 10 days of August and on three days in October, nine days in November and every day in December and January. The health department issued the sanitary authority a notice of violation on Jan. 7.

Yesterday's four-page, 15-point order was accompanied by a cover letter stating that the department had determined the sewage discharges "constitute health hazards."

"There is no threat to drinking water supplies, but the discharges are fouling the Youghiogheny and its tributaries in Elizabeth and if anyone came in contact with the sewage they could become infected," Mr. Cole said. "That's more likely in warmer weather and one of the reasons the order requires that warning signs be posted at all discharge points by March 20, when river recreation will begin to pick up."