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Massachusetts Water Resources Authority
July 1, 2008
CONTACT: Ria Convery, Communications Director
(617) 788-1105, <>



MWRA's Memo in Response to US Motion July 1, 2008 (PDF)
Statement from the MWRA Advisory Board (outside link)
Boston Harbor Case Compliance Reports
Measuring Water Quality in Boston Harbor and Massachusetts Bay
Outfall monitoring overview (PDF)
NPDES (Permit) compliance report (PDF)
Review of toxic contaminants in Boston Harbor and Massachusetts Bay (PDF)
Benthic nutrient flux (PDF)
Outfall benthic monitoring (PDF)
Outfall monitoring science advisory panel on EPA’s website
OMSAP minutes
(USGS) report on contaminated sediments in Boston Harbor and Mass Bay

The outfall for MWRA's Deer Island Treatment Plant is instrumental to the harbor's recovery. It started up in September, 2000 and discharges treated sewage, called effluent, into Massachusetts Bay. Mass. Bay's water is deeper and allows for much better dillution of the effluent than the shallow water of Boston Harbor.

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The Deer Island Treatment Plant was designed and permitted with the understanding that, at times, primary treated only wastewater would be "blended" with secondary treated flows and disinfected, provided that the final blended effluent met secondary permit limits. During the blending process, flows in excess of the secondary treatment process limit are routed around the secondary treatment step. These flows are then blended back together prior to disinfection, dechlorination, and discharge.This practice is allowed for treatment plants that service collection systems that have some combined sewers and are subject to large fluctuations in flow.

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Today, the U.S. Environmental Protection Agency released a statement claiming that the settlement of an administrative dispute with the Massachusetts Water Resources Authority will result in a “higher level” of wastewater treatment at Deer Island.

While the matter has been settled, MWRA disagrees with the fundamental premise of EPA’s claim that 22 billion gallons of wastewater did not receive adequate treatment between 2001 and 2005 and that EPA is now responsible for a change in the treatment process.

Since the outfall came on-line in 2000, every gallon of wastewater leaving Deer Island received treatment. And, in fact, MWRA has consistently met stringent water quality standards. The quality of the discharge has been better than predicted and is twice as clean as the limits established by EPA itself.

The fact of the matter is that the improvements to the treatment process were completed by MWRA in 2005 – on its own and without any directives from EPA - after a series of multi-million dollar upgrades were made to the plant.

Because the Deer Island Treatment Plant serves combined sewer communities, it was designed and permitted with the understanding that, at times, wastewater receiving only primary treatment would be “blended” with secondary treated flows and disinfected, as long as the final blended discharge met secondary permit limits. This is how the plant is supposed to work and MWRA “blended” flows as recently as last Friday, and will continue to do so during high flow conditions.

From day one, MWRA has made no secret of how it operates the Deer Island plant.  EPA receives detailed monthly reports describing MWRA’s operating practices and their results. MWRA was under the assumption that EPA had been reading these reports. 

MWRA’s settlement of this claim is purely a business decision and is in the best interest of MWRA ratepayers, instead of a costly legal battle.

EPA initially threatened MWRA with a fine of over $80 million.  But after three years, MWRA has negotiated a settlement which includes a payment of $305,000 and three projects with a value of $305,000 which will provide additional environmental benefits to Boston.

The Boston Harbor clean-up is widely recognized as one of the nation’s true environmental success story. Teams of scientists constantly monitor the MWRA’s outfall discharges.  The results of all of these studies confirm that Boston Harbor has recovered quickly and that Massachusetts Bay remains healthy and environmentally vibrant.


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Updated July 7, 2008