Cleaning that dirty water

The refrain from the Standells’ top-40 hit “(I Love That) Dirty Water” may not properly refer to Boston Harbor for much longer.

When the song was written in 1966, the lyrics correctly summed up the state of Boston’s waterways: murky and polluted. The sewage-filled harbor was the last place residents and visitors turned for summer swims, and the Charles River was polluted with mercury from a Polaroid manufacturing plant located upstream.

By the mid-1980s, Boston Harbor had earned a reputation as the filthiest harbor in the nation and was so dirty that, according to urban legend, a Quincy city official running along the harbor’s edge once stepped on a piece of raw sewage.

But the harbor has made leaps and bounds since 1985 after a federal lawsuit ordered an overhauling of Boston’s waste management system and the cleaning of the harbor to the greatest extent possible. Today, marine life is returning, microorganisms are slowly cleaning harbor-floor sediment and Boston Harbor beaches are open for swimming 95 percent of the year.

Though the road to environmental rehabilitation has been difficult, it has been worth the time and $3.5 billion expense, said Jonathan Yeo, a spokesman for the Massachusetts Water Resources Authority, a private firm set up to oversee harbor cleaning efforts.

“It came at a cost,” Yeo said. “But it is one of America’s greatest environmental success stories.”

OVERHAULING THE SYSTEM

When the authority was created in 1985, its to-do list ranged from rebuilding the Deer Island sewage treatment plant to extending wastewater drainage pipes miles into Massachusetts Bay.

The plant at Deer Island, which should have been renovated as part of the 1972 Clean Water Act, was funneling raw sewage directly into the inner harbor.

“Our predecessor agency … had allowed the waste water treatment plant to fall into disrepair,” Yeo said. “They hadn’t upgraded it, and the harbor was in terrible shape.”

The Deer Island plant was so inefficient, according to a 1998 Harvard University study, that nearly 175 tons of solid sewage were being dumped into the harbor daily in 1988. That number is nearly 25 percent more than the amount of sludge released daily in 1998 by the new Deer Island plant, which was finished in 2000 and is the second largest wastewater treatment facility in the country.

The MWRA also had to relocate sewage pipes further offshore so polluted liquids could spread out at the Environmental Protection Agency’s recommended dispersion rates. Wastewater now goes into Hingham and Quincy bays and near Deer Island instead of directly adjacent to downtown.

The authority also set up wastewater monitoring points throughout the harbor to help scientists collect data on wastewater concentrations.

THE FLUSHING PROCESS

Although the new programs and facilities have drastically improved wastewater treatment, purifying nearly 1.3 billion gallons of wastewater is still no easy task.

The MWRA does not clean water by pumping existing harbor water into Deer Island and purifying it. Instead, the plant treats new sewage-ridden liquids and pumps cleaner water out into the harbor.

Sewage arrives at Deer Island through four underground tunnels. The water then flows into separation chambers where solids float to the top to be separated from the liquids. Filters 186 feet long and 41 feet high then clear the water of smaller impurities.

A similar process is repeated using microorganisms as the main filtration system to consume remaining unwanted particles.

The wastewater is then flushed with sodium hypochlorite to kill any remaining bacteria. Sodium bisulfate then de-chlorinates the water before it travels about 10 miles out to Massachusetts Bay.

More than 100,000 wastewater analyses monitor the process each year to make sure discharged water meets requirements. So far, tests show the plant has been a huge success, Yeo said, noting that they received a top EPA award last year.

THE TRIBUTARIES

Cleaning the sewage flow into Boston Harbor is only one part of the project. Environmental groups continue to clean the harbor’s tributaries – the Charles, Mystic and Neponset rivers.

Since 1965, the Charles River Watershed Association has been working to make the river a clean water supply for the harbor.

“If you can clean up the Charles, you have one less dirty discharge to the harbor,” said Kathy Baskin, a project manager who has worked with the CRWA for eight years. “If you do that, the whole harbor will start to come back.”

The association has tackled what it believes is the main cause of pollution – a wastewater system designed in the 1800s that combined street runoff and sewage in one pipe.

“It was state-of-the-art to put storm water and sanitary waste in one spot,” she said. “But when there is a lot of rain, the system gets choked up, overflows and there is raw untreated sewage combined with wastewater discharging into the river.”

Baskin said leaking sewage has been almost completely contained thanks to area cities and towns’ investments in new sewer systems.

But Baskin said she is unsure about whether the EPA will meet its 1995 goal of making the Charles safe for swimming and fishing by 2005.

“Whether or not they meet that goal is still in question,” she said. “Whether or not we do … if we continue to clean the Charles up, it still helps the river and the harbor.”

THE HIDDEN PROCESS

Along with the government organizations and public interest groups helping to achieve the harbor’s environmental gains over the last 20 years, a 2002 University of Massachusetts at Amherst study found microorganisms may be slowly cleaning the harbor’s floor.

The study headed by UMass professor Derek Lovley discovered that small microbes on the harbor floor digest sulfates and polycyclic aromatic hydrocarbons – two common pollutants.

Although some members of the scientific community are skeptical about Lovley’s theory, his findings could provide hope that the harbor floor’s condition may improve drastically in as little as 10 years.

“This is important because it demonstrates that the self-purification capacity of the harbor is much greater than previously recognized,” Lovley said in a statement. “It does give us hope for the longer term if practices change.”

THE FUTURE

But plenty of work remains.

Yeo said the MWRA continues to work with cities to renovate leaking sewer systems and to reroute street runoff into the wastewater system.

“We’re getting close to as far we can go,” he said. “The biggest water quality problem is storm water drainage, and that is the responsibility of local cities.”

The authority will also continue to maintain Boston’s wastewater infrastructure even after most system modernizations are complete.

“There will always be wastewater programs, and we’re going to have to maintain what we already have,” Yeo said. “What comes out of our toilet isn’t going to change.”