Outfall pipes from Manchester, N.H., to Lawrence and Haverhill are dumping hundreds of millions of gallons of raw sewage and stormwater into the Merrimack River annually, bypassing treatment plants that have undergone costly upgrades to capture the overflow but still are not up to the task.
The foul discharge into the Merrimack is just a small part of a flood tide of pollution flowing into waterbodies documented by the New England Center for Investigative Reporting in a new report. (See accompanying story.)
NECIR tallied the overflows from dozens of sewer plants in six states in 2011, and found 7 billion gallons. That included 823 million gallons that went into the Merrinack.
On the Merrimack, the worst offender is Manchester, which sent 372 million gallons downriver in 59 separate spills in 2011, the latest year for which data is available, sending it past communities — including Lawrence, Methuen and Andover — that draw drinking water from the Merrimack.
Manchester officials disputed the number, and the plants that treat drinking water drawn from the river are designed to handle the contaminants. Nevertheless, on the worst days after the heaviest rains, Merrimack beaches are closed to swimmers, advisories are issued to boaters and the whiff of sewage floats over the river’s banks.
Lawrence poured another 42 million gallons of untreated sewage and stormwater into the Merrimack from outfall pipes on Osgood Street and Island Street in 2011, the last year for which numbers are available, NECIR reported after a review of records provided by sewage systems in the six states.
Haverhill poured in 36 million gallons more from 10 pipes on the Merrimack and Little rivers. Lowell and Nashua, N.H., dumped in a total of 272 million gallons.
The NECIR tallies do not include the 300,000 gallons that a Hooksett, N.H., treatment plant discharged into the Merrimack on March 6, 2011, a spill that received wide attention because it included as many as 8 million plastic disks, each a little larger than a half-dollar, that were used to hasten the treatment process in tanks at the plant. The disks washed up on shorelines well beyond the mouth of the Merrimack, turning up as far away as Maine and Cape Cod.