A new report details how Baltimore has deliberately dumped more than 330 million gallons of raw sewage over the past five years into the Jones Falls, which flows to the Inner Harbor.

Elsewhere in the city’s 1,400-mile network of aged underground pipes, the report by the Environmental Integrity Project notes, there have been more than 400 complaints of sewage backing up into homes.

The intentional overflows — releasing 15 times as much sewage as the city has reported spilling from pipe breaks and blockages — are coming from two openings in the sewer system that the city was supposed to close years ago, according to the Washington-based environmental group. The releases are intended to avoid sewage backups into homes from the city’s leaky, overloaded sewer system.

The report, based on public information requests, comes as the city is nearing a deadline for fixing the system that it will not meet.

City officials say they have spent $700 million on sewer repairs to comply with a consent order signed in 2002 with the U.S. Environmental Protection Agency and the Maryland Department of the Environment. The order, settling a lawsuit brought against the city for polluting local waters, requires an end to chronic overflows by Jan. 1.

But with just over two weeks to go before the deadline, the city has completed only about half the repairs and upgrades it pledged to make, according to the report.

Jeff Raymond, spokesman for the city’s Department of Public Works, said municipal officials hope to get an extension from state and federal regulators. But he added that he couldn’t discuss how much longer the overhaul would take until a new timetable is filed with the federal court. Officials previously said they expect to spend more than $1 billion to complete it.

The environmental group and local activists are calling on state and federal regulators to grant the city no more than five more years to finish its sewer work, in keeping with a campaign the city has embraced to make the harbor swimmable and fishable by 2020.

“They need to get it done,” said Eric Schaeffer, a former EPA official who directs the Environmental Integrity Project. “It’s been 13 years now,” he said. “They need to pick up the pace.”

Activists also are insisting on alerting people around the Inner Harbor to the health risks of kayaking, sailing or otherwise coming into contact with water frequently contaminated with sewage.

“We’re seeing a lot more people out on the water boating and fishing,” said David Flores, the Baltimore Harbor Waterkeeper, contending that the city ought to be more open about how much sewage is being spilled into the harbor and the streams that feed it.

Decades ago, the city designed its sewer system to overflow into the nearest stream whenever sewage backed up in the lines. Since signing the consent decree, the city has closed 60 of 62 built-in relief valves. But officials say that if they close the last two overflow outfalls on the Jones Falls, it could cause sewage to back up into homes and businesses throughout much of the city.

“Our regulators are aware that these are open,” Raymond said. City officials plan to plug the overflows “down the line,” he added.

Many of the overflows are occurring because of a problem with the pipe feeding into the century-old Back River wastewater treatment plant, officials say. The city planned to issue a contract last summer to remedy the backups by pumping sewage into massive holding tanks, but officials rejected the low bid because it was more than $100 million over the $300 million municipal engineers had estimated.

City officials are reviewing the project to figure out how to lower the cost, Raymond said. Construction is now projected to begin in 2017 and take three years.

Activists contend that the city isn’t being open enough about how much sewage is being spilled or what risks the public faces. Water samples taken regularly by the city since 2009 show potentially unsafe levels of fecal bacteria occur frequently in the Inner Harbor and the lower Jones Falls.

The city is required by state regulation to alert the public whenever there is a sewage spill or overflow of more than 10,000 gallons. But the much larger releases from the two built-in overflow valves on the Jones Falls are not reported promptly and only rarely get announced to news media or the public, the report noted.

Edward J. Bouwer, professor and chairman of the Department of Geography and Environmental Engineering at Johns Hopkins University, said he believes the city ought to be posting warning signs around the Inner Harbor. “I suspect that people out there have no idea,” Bouwer said.

“I wouldn’t say, ‘Kayakers, don’t kayak.’ Just be aware that the water has high fecal levels. If it gets in the mouth, that could cause someone to get sick.”

Halle Van der Gaag, executive director of the local environmental group Blue Water Baltimore, said she’d like to see regulators and the city address the residential sewage backups detailed in the report. Any plan to correct the overflows also should offer relief to residents whose homes have been fouled through no fault of their own, she said.

“This isn’t just about kayakers on the Inner Harbor,” she said. “It’s about people being impacted in their homes. It’s disgusting.”

Sewage backups have been reported from all over the city, according to the report, but there has been a flurry of them in a few Northwest Baltimore neighborhoods.

Charles and Doris Brightful, longtime residents of Grove Park, say their basement has flooded with raw sewage twice in the past two years during heavy rainstorms. In the most recent episode in late September, foul-smelling waste seven or eight inches deep filled their basement, they said. They wound up having to replace the furnace, hot water heater and the furniture they had recently purchased to replace what they had tossed after the backup from the year before.

The city also is eyeing installing a “backflow preventer” in the sewer main in the Brightfuls’ neighborhood, he said.

“That is still on the drawing board,” Raymond said. “We don’t have a solid time frame for that.”

Meanwhile, Charles Brightful said, “Every time they mention rain, I get paranoid.”