Trash and debris collect along the shores of the Anacostia River near Nationals Stadium in Washington, D.C. (Linda Davidson/The Washington post)

For environmental activists who fight to clean the District’s dirty waterways, there was no sweeter victory than the one they witnessed in 2004.

That year, the D.C. Water and Sewer Authority was forced to settle a federal lawsuit that claimed it failed for decades to stop its Civil War-vintage sewers from spewing pollution. D.C. Water agreed to build three huge tunnels within 20 years to stop pipes from overflowing during hard rains, sending billions of gallons of storm water mixed with raw sewage into Rock Creek and the Potomac and Anacostia rivers every year.

“Maybe . . . before I pass away, I can see children swimming in there,” Robert Boone, the former president of the Anacostia Watershed Society, said shortly after the settlement was reached.

But now, the three-tunnel solution is in doubt, and activists, engineers and bureaucrats are arguing once again about the best path to cleaner waters. Although digging is underway for the first tunnel, D.C. Water wants to put the other two on hold and instead see whether rain gardens, retention ponds and grass rooftops can soak up as much storm-water runoff as the pipes can store.

D.C. Water has asked the Environmental Protection Agency for permission to build an experimental “green infrastructure” project and run tests for at least eight years.

The green project would be built where the second and third tunnels were slated to run, along Rock Creek Parkway near the Kennedy Center to protect the Potomac River and in Upper Northwest neighborhoods to protect Rock Creek. A 13-mile tunnel under the Anacostia River and deep into the Northeast near a Home Depot off Rhode Island Avenue, currently under construction, would continue as planned.

The EPA is considering D.C. Water’s proposed “partnership agreement,” and a decision on whether to move forward with public hearings on the changes is expected soon.

Among local environmental activist groups, a verdict on the request is already clear: Don’t do it. Some are enraged; others have expressed dismay about the proposal.

“We’re well down the road to the tunnel solution, and I’m a little ambivalent about changing course midstream,” said Brent Bolin, a spokesman for the Anacostia Watershed Society.

Opponents say that if the green pilot project wins approval, billions of gallons of sewage would pour into the Potomac and Rock Creek for eight years while D.C. Water conducts its tests.

The proposed agreement played a major role in the recent firing of the head of the D.C. Department of the Environment (DDOE), Christophe Tulou. He said he believed the green infrastructure project had no hope of performing as well as the utility claimed, and he allowed experts in his department to say as much in comments on the project submitted to the EPA.

In a recent interview at his home, Tulou, now unemployed, said his department “had no beef about green infrastructure. But there are still issues one has to resolve . . . how effective is green infrastructure in mitigating storm-water runoff. We don’t know exactly.”

But others who support Tulou were more harsh in their criticism, saying green infrastructure is a stall tactic, an attempt to delay a portion of the $2.6 billion cost of the Clean Rivers tunnel project.

“From our perspective, this proposal is purely about delays . . . that is the purpose behind it,” said Jennifer C. Chavez, a staff attorney for Earthjustice, a nonprofit legal organization that represented several groups in a lawsuit against the utility in 2000.

D.C. Water’s general manager, George Hawkins, has said the “green” project is superior to the “gray” pipes because it would cool and beautify the city if tests are successful and the program is allowed to expand.

Hawkins convinced Mayor Vincent C. Gray (D) of the project’s worthiness early last year. Gray sent two letters of support to EPA Administrator Lisa P. Jackson in March and July, without consulting experts in his office for their opinions on whether it would work.

D.C. Council Chairman Phil Mendelson (D) initially favored green infrastructure, but not at the expense of the two tunnels in the original agreement. When Mendelson learned that D.C. Water and city officials were negotiating a partnership agreement, he also wrote a letter to the EPA administrator, withdrawing his support for the green project.

Green infrastructure should be included with all three tunnels or be left out altogether, Mendelson wrote. To clean the water, the District needs what D.C. water originally agreed in court to build, not a hybrid of a tunnel for the Anacostia watershed and something else for Rock Creek and the Potomac.

According to Tulou, Shawn Garvin of the EPA asked his department to submit comments on D.C. Water’s proposal. Within days, DDOE submitted comments that said the “green infrastructure” project was vague, lacking information on how the tests would be conducted, who would pay for the upkeep and maintenance of the gardens and a detailed estimate of how much pollution would pour into the rivers and creeks during testing.

Gray felt that his support for the project was being upstaged. On the last day of August, Tulou was terminated by City Administrator Allen Lew, who sits on D.C. Water’s board of directors.

Lew said DDOE’s criticism represented a “breach of protocol.” Gray replaced Tulou with Keith A. Anderson, who oversaw sustainable energy and affordable energy plans at DDOE.

An official in Gray’s administration, who spoke anonymously because firings are a personnel matter, said Tulou’s problems went beyond his department’s criticism of D.C. Water. The official said he was often unaware of what his staff was doing, and that he was too by the book to understand an experimental project like green infrastructure.

That characterization surprised one of Tulou’s former supervisors, Sen. Thomas R. Carper (D-Del.), who appointed him as secretary of the state Department of Natural Resources and Environmental Control when he was governor of Delaware.

“I loved Christophe and did so for 10 years,” said Carper, who served from 1993 until 2001. Carper credited Tulou with successfully drafting rules for development in a sensitive coastal area.

“He was great at it,” Carper said. “He’s very good at collaborating. His skill at getting us to yes on a complex issue . . . is viewed by me as important.”

Tulou’s dismissal stung environmental activists, who now question Gray’s commitment to the environment, particularly in light of recent actions and statements by Lew.

After Tulou’s firing, Lew met with his former staff and warned them against making comments to EPA before getting clearance. His talk had a chilling effect, particularly after a report in the Washington Business Journal suggesting that some of its environmental protections overstepped its role.

“I do think it would be fair to say the city administrator is taking a look at the agency to ensure that it’s working the way it’s supposed to . . . that it’s carrying out its regulatory responsibility but . . . not overstepping its role as regulator and moving into the role of advocate,” Tony Robinson, Lew’s spokesman, was quoted as saying.

As far as some environmentalists are concerned, Lew’s talk at DDOE and Robinson’s statement reveal a lack of understanding of the department’s role.

“DDOE is the environmental conscience of the District,” said Chavez of Earthjustice. D.C. Water and commercial developers often have much higher priorities than protecting fresh waters. “That’s why it’s important for DDOE to be there to weigh in on environmental standards, and we haven’t seen that,” Chavez said.