Signage warns about sewage where it enters the Potomac river at the Oronoco outfall in Alexandria, Va. (Bill O'Leary/The Washington Post)

The Virginia Senate on Thursday voted to give the city of Alexandria almost eight years to stop its antiquated sewer system from sending raw sewage into the Potomac River, stepping back from a demand that the city act by 2020 or lose all state funding.

The compromise, which must also pass the House of Delegates, was forged between Sens. Richard H. Stuart (R-Stafford) and Adam P. Ebbin (D-Alexandria).

Stuart, whose original legislation would have stripped state funding from the city if the problem wasn’t solved within 3 1 /2 years, agreed to amend the bill to include a longer timetable and remove the financial penalty.

Alexandria Mayor Allison Silberberg (D) objected to the 2025 deadline Thursday, saying engineers have identified multiple regulatory and structural issues involving the sewer system that will that take years — and millions of dollars — to resolve.

Silberberg said the city will make its case to the House later this session.

Signs warn about sewage where it enters the Potomac River at the Oronoco outfall. (Bill O'Leary/The Washington Post)

“We feel [a deadline of] 2029 is a more reasonable amount of time, and it will be a huge push to accomplish that,” she said. “I want to do this right, and I want to know how we’re paying for this.”

Stuart said he’s willing to fight back if the city refuses to meet the 2025 date.

He noted that before his bill came to the legislature, Alexandria was planning to delay action on its biggest overflow site until the mid-2030s. He said he threatened to yank $130 million in state funds to get the attention of city leaders, with the goal of forcing a speedier cleanup.

“I grew up on that river. I’ve seen the damage. You used to be able to see the bottom,” he said during a Tuesday floor debate on his bill. “These are serious health issues that face us and the people downstream from Alexandria. . . . We have to live in the sewage they dump in the river. That’s unfair to the people I represent.”

While some Republican lawmakers joined his criticism of Alexandria, several Democrats objected to the heavy-handed tactics.

“You pull a stunt like this and sometimes you don’t get the help you need when it needs to be reciprocated,” Sen. Richard L. Saslaw (D-Fairfax) warned.

Alexandria plans to ask the General Assembly for state funding to help replace its outdated combined sewer systems, funding that Richmond and Lynchburg already received. City officials noted that neither of those cities have come in for the kind of criticism directed at Alexandria.

“The city is being asked to do something in 7½ years that normally takes other communities a generation,” said Yon Lambert, Alexandria’s transportation and environmental services director. “This is an enormous, unfunded mandate equivalent to $300 million or more.”

The political power play began in September, when Sen. Scott Surovell (D-Fairfax) took to social media to chastise the city for not moving more quickly to fix the sewage overflows, which happen whenever rain runoff overwhelms the two-century-old combined storm water and sewer system. Surovell’s district sits just downriver from Alexandria.

City Council members, past and present, immediately defended themselves and asked why Surovell wasn’t offering solutions.

Surovell subsequently proposed legislation pushing for faster action on the overflows. But Stuart’s bill, with its tougher penalty, is the one that got to the floor of the Senate this week.

Alexandria submitted plans to the state this fall outlining how it intends to fix overflows from three of its “outfalls,” as the combined pipes are called. Those plans were required by the federal Clean Water Act, which the state administers. The repairs will cost an estimated $188 million and will add $10 to $15 per month to the average residential sewer bill.

The fourth and biggest outfall, which dumps 11 million gallons of raw sewage into Oronoco Bay each year, was not part of the federal mandate and thus was left out of the plan.

Environmentalists and local residents have been pressuring the city to act on the Oronoco Bay site as well. In November, the council ordered city employees to speed up their study of the issue by 14 years.

The Potomac Riverkeeper Network is seeking a state-sponsored public hearing on the issue, and the U.S. Environmental Protection Agency has started to ask questions about how the city will deal with the Oronoco Bay issue.

In an interview, Ebbin said he wasn’t thrilled with the compromise bill approved in the Senate on Thursday, but felt it was far less onerous than what Stuart originally proposed.

“I don’t think having 140 amateur environmental regulators is the best approach,” Ebbin said, referring to the state’s elected leaders. “That said, an eight-year deadline is better than a three-year deadline.”

Gregory Schneider in Richmond contributed to this report.