The Gowanus Canal is extremely polluted — no one disputes that fact. But lawmakers, elected officials, and residents have bickered over what to do about it for decades. The 1.8-mile, 100-foot-wide, 20-foot deep waterway is in the heart of Brooklyn, sandwiched between two popular neighborhoods, and flows from Butler Street out to the Gowanus Bay.

On March 2, 2010, there was an answer: the federal Environmental Protection Agency (EPA) designated the waterway a Superfund site, a list reserved for the country’s dirtiest hazardous waste hotspots. The ruling [pdf] sets into motion a 12-year, $500-million clean up, to be funded by the companies the EPA determines caused the pollution. Early tests show that the 330,000 cubic yards of contaminated sludge at the bottom of the canal is filled with heavy metals, PCBs, and thick black coal tar — remnants from 150 years of storm water runoff, sewer outflows, and industry and manufacturing, including manufactured gas plants, oil refineries, coal yards, tanneries, paint and ink factories, and machine shops. The variety of contaminants complicates the clean up because each must be dealt with separately, said the EPA’s Regional Superfund Director Walter Mugdan.

Construction on the canal's flushing tunnel and pumping station began at the end of 2009.

But Superfund opponents, including Mayor Michael Bloomberg, are concerned that the designation will stigmatize the neighborhood and make developers think twice about building in the neighborhood. Already, development company Toll Brothers pulled its plans for a 450-unit canal-side condominium and esplanade complex. Hudson Companies, which envisions a mixed-income housing and open space along the canal, acknowledged that the designation presents new challenges for financing and construction, but is still pursuing the project.

The EPA estimates the cleanup will take 10-12 years, a timeline that is “absolutely as fast as it can be done,” Mugdan said. Currently, scientists are in the remedial investigation phase, figuring out what contaminants are in the canal, where they’re coming from, where they’re going to, and how deep they are. Next year, engineers will come up with alternative solutions about how to deal with the contaminants in a phase known as “the feasibility study.” The EPA will then present the alternatives to the community and get feedback.  By the middle of 2012, Mugdan said they will select a cleanup program. Engineers will then design the actual work plan, a three-year process that is further complicated in the Gowanus Canal because of its narrow banks and busy surroundings. Work to dredge and clean the canal will begin by 2014 or 2015, Mugdan estimated, and it will most likely be removed via pipeline or a barge.

“The challenge is what to do with [the mud] once you got it,” he said. Engineers will remove the water, but both the sediments and contaminated water must be treated separately.

Parts of the land alongside the canal are also contaminated. Mugdan said the EPA is studying how the contamination spread in the past, whether it is still spreading, and, if so, how to stop it. Two likely culprits are ground water seeping through these uplands and pipes that empty into the canal.

“Our task is to make sure that any ongoing pollution to the canal is eliminated by the time we clean the canal, so it doesn’t get just dirty again after we’ve cleaned it,” Mugdan said.

Under the Superfund law, companies that polluted the water in the past are responsible for funding the cleanup today.   So far, the EPA has identified at least nine companies, including National Grid, Consolidated Edison, the U.S. Navy, New York City, and several petroleum companies.  Mugdan estimated the project will cost between $300 million and $500 million, explaining that federal funding is only used in cases of an abandoned property or now-bankrupt companies that once polluted.

But cleaning the sediment isn’t the only challenge the EPA faces in the cleanup. During big storms, rains overflow the city’s aging sewer system and cause raw sewage to flow directly into the water, a stinky process known as “combined sewer overflows,” or CSOs. The city Department of Environmental Protection is in the midst of a three-year, $150-million project to rehabilitate the canal’s flushing tunnel and pumping station to reduce one-third of these CSOs away from the canal and increase the flow of clean water through the waterway. Sediments at the head of the canal, near Butler Street, will also be dredged.

Work has started on the city’s plan and is on schedule, said Bloomberg spokesman Marc LaVorgna. The project is separate from the EPA’s work, but LaVorgna said the city will work closely with the EPA “because we share the same goal — a clean canal.”

In the future, the companies that polluted the canal and are funding the cleanup are also responsible for maintaining a clean waterway, said EPA spokeswoman Beth Totman. Every five years for as long as there is contamination, EPA scientists will review the canal to ensure the companies’ remediation plans are in effect and are working properly.

“Our goal is to have the fish be edible,” Totman said. “It would be ideal if you could swim in these waters, but our goal is to ensure this waterway is turned back to the community so they can use it.”

For more information on the EPA’s Gowanus Canal cleanup, visit the department’s Web site, Facebook group, or contact community involvement coordinator Natalie Loney at (212) 637-3639 or loney.natalie@epa.gov.