The result, according to government officials? Instead of an average of eight beach closures each summer, there will be, at most, an average of one in five years.
“Now, parents can let their kids swim even after a rainstorm without the fear of getting diseases,’’ said Peter Shelley, senior counsel of the Conservation Law Foundation, a Boston-based environmental group that 28 years ago filed one of the main lawsuits demanding that the harbor be cleaned. “We did this so people can use the harbor.’’
Said Massachusetts Water Resources Authority executive director Fred Laskey: “It really will be among the cleanest urban beaches in America.’’
The $225 million tunnel is one of the last major pieces of the nearly $5 billion harbor recovery — and one of its most controversial because of its location and cost. Advocates have long celebrated the harbor’s renaissance, evident in the return of clammers who dig in urban sands, the disappearance of tumors on fish, and a building boom on its shores. But the water still wasn’t always safe at the city’s most popular beaches.
The problem was twofold. During particularly heavy storms, raw human sewage and storm water mixed in the labyrinth of pipes under Boston. When the sewer system became overwhelmed — about 20 times a year — the bacteria-filled soup poured into the harbor.
During more moderate rains, storm water runoff, carrying animal waste, sewage from illegal hookups, debris, and lawn fertilizer, also flowed into the harbor 105 times a year, on average.
If bacteria counts were high enough during the summer, beaches also closed. During the winter, the releases were believed harmful to marine life.
Now, MWRA officials say, the combination of sewage and storm water will flow into the harbor on average once every 25 years. Storm water alone will enter the South Boston area on average only once every five years, they predict.
The harbor cleanup is still not done; intensive work continues to clean the Charles, Mystic, and other rivers that flow into the harbor. But those projects will have a negligible effect on swimming quality in South Boston and Dorchester.
