The D.C. government’s former environmental director said he was wrongly fired by Mayor Vincent C. Gray (D) for voicing concern over an effort to delay a multibillion tunnel project designed to stop massive amounts of wastewater from washing into the city’s polluted rivers and creeks.

In a federal whistleblower complaint filed at the U.S. Occupational Safety and Health Administration last week, Christophe Tulou said his firing in August was in retaliation for expressing concern to the Environmental Protection Agency about a proposal to delay a portion of the tunnel for eight years while the city used an experimental “green” project to soak up storm water. He told the EPA there was reason to doubt the experiment, which the mayor supports, would work as well as the pipes called for in the original plan.

Tulou, who led the D.C. Department on the Environment (DDOE), said he and his staff were worried that if the experiment failed, the city would fall short of its obligation to clean Rock Creek and the Potomac and Anacostia rivers as required by a 2005 consent decree under the Clean Water Act. The giant tunnel project is part of a wider multibillion effort to comply with the decree.

The waters are so polluted from sewer overflows and dirty rain runoff that swimming is forbidden and eating fish is discouraged. The green project would be a substitute for a planned portion of pipe near Georgetown to protect the Potomac River and Rock Creek in upper Northwest. A 13-mile portion of pipe slated to run under the Anacostia River into Northeast Washington would not be affected.

“It was clear to me what we were doing was representing the public interest,” Tulou said in an interview Wednesday.

In early August, City Administrator Allen Lew called Tulou into a meeting with his chief of staff and fired him for what the city later described as a “breach of protocol.”

Tulou is seeking reinstatement to his job, repayment of loss wages, the expunging of negative information in his personnel file and court costs. His whistleblower complaint was first reported in the Washington Times.

The complaint alleges that the mayor’s office used Tulou’s firing as a demonstration of the consequences of “going outside the chain of command” to offer criticism to the EPA.

On Sept. 6, Lew called DDOE staffers into a meeting, the complaint said, allegedly quoting the accounts of people who attended. “If the mayor has already issued something and you want to make some . . . corrections, you communicate that internally to us.

“[You] work for D.C. government, not interest groups — realize which side of the bread is buttered,” Lew was quoted as saying.

Local environmental interest groups support the Clean Rivers initiative to plug 53 sources of raw sewage overflows. They like green projects in theory, but prefer new “gray” pipes, because their ability to divert and store wastewater is proven.

Tony Robinson, Lew’s spokesman, said the complaint’s account of the meeting was taken out of context. “The purpose of the meeting was solely to say to staff that they had the mayor’s sole and complete support” despite the firings, Robinson said.

Robinson said the tone of Lew’s remarks was gentle.

Lew told staffers that he knew they had relationships with EPA officials, and encouraged discussion, but said that official communication must go up the chain of command and conform with policy, Robinson said.

“It had nothing to do with trying to silence anybody,” Robinson said. “That’s a point he underscored in his comments that they should feel free to talk to the EPA.”

But Linda Correia, an attorney for Tulou, said the meeting supports the case that Tulou’s firing was in retribution for performing his job as the city’s foremost technical expert on wastewater’s impact on the environment. She said the meeting amounted to intimidation.

“We think it’s a powerful case,” Correia said. “There’s no mistaking the linkage of the comments provided to EPA, the reasons for termination of employment and the statements Mr. Lew made to employees at the meeting. It’s retaliation.”