Most harbors and estuaries in the Northeast bear the signature of long-standing industrialization and urbanization on their shores. These problems, that have only recently begun to be recognized and remediated, range from toxic materials in sediments at the bottom of estuaries; to shellfish waters and bathing beaches being closed by fecal pollution; to excessive nutrients causing phytoplankton blooms and resulting hypoxic or anoxic waters; to tidal wetlands converted to buildable land or isolated from coastal saline waters by inadequately-designed road and railroad bridges. Boston Harbor is an example of such an estuary that has been altered and polluted by human activityÑbut which is now on the rebound as some types of anthropogenic impacts have been reduced.
Boston Harbor has a position of prominence in the nation's history from the beginnings of the American Revolution to a focal point of the 1988 presidential election when it was showcased one of the nation's dirtiest bodies of water. Significant pollution of Boston Harbor dates back to at least the 1870's when the "Boston Main Drainage System" collected sewage from 18 municipalities in the region and conveyed it to Moon Island in the Harbor for release on ebbing tides. No treatment of the sewage occurred before release.
Moreover, like most cities in the Northeast, Boston's sewer system is made up largely of "combined sewers" or piping that conveys both sanitary sewage and stormwater flow. To accommodate the vastly increased flow volume associated with storm events, combined sewer systems are designed with numerous "release valves" termed CSO's or "combined sewer overflows" that release a mixture of stormwater and raw sewage into the Harbor during significant rainfalls. These CSO's remain in Boston and many other northeastern cities.
Through the late 1800's and into the early 1900's Boston's sewer system continued to grow. By the 1930_s the volume of untreated sewage being released into Boston Harbor caused severe restrictions to be placed on harvesting shellfish resources. Two sewage treatment plants were constructed, one on the Harbor's Nut Island in 1952 and a second on Deer Island in 1968.
However, these treatment plants only provided minimal processing of the millions of gallons of sewage that passed through them each day. This inadequately treated flow still continued to pollute Boston Harbor. In fact at the Deer Island plant, raw sewage received only limited primary treatment (i.e., settling out of some of the suspended solids in the sewage). The separated sludge, partially reduced in volume, and the liquid effluent were then both released into Boston Harbor. By 1986, this combination of treated effluent and sludge represented over 120 tons of solids per day dumped into the Harbor. These solids and associated scum made the harbor water cloudy and unappealing; covered much of the harbor bottom, changing the composition of organisms living there; and contributed to reduced dissolved oxygen concentrations in the water and in the harbor bottom's sediments.
Although the Boston area communities served by the Metropolitan District Commission (MDC), the agency responsible for managing wastewater entering the harbor, and the Commonwealth of Massachusetts had the responsibility to improve the deplorable conditions that existed in Boston Harbor, they did little. Required under the 1972 federal Clean Water Act to bring the treatment of wastes entering Boston Harbor up to a level called secondary treatment (i.e., 85% removal of suspended solids and 85% removal of organic material termed biochemical oxygen demand or BOD), the MDC and the Commonwealth sought a waiver from this requirement for more than ten years.
Reacting to the sorry state of the Harbor and the inability of the MDC to improve conditions, the City of Quincy, MA, sued the MDC in 1982 for violations of Massachusetts' water quality regulations. This suit was quickly followed in 1983 by one in which the Conservation Law Foundation, an environmental advocacy organization, sued the MDC and the U.S. Environmental Protection Agency (EPA) for failing to protect Boston Harbor. Finally, in 1985 the EPA sued the MDC and the MWRA. The MWRA (the Massachusetts Water Resources Authority) had been created by the Commonwealth to take over the MDC's sewer and wastewater treatment responsibilities.
In 1986 in U.S. District Court, the MWRA and the Commonwealth of Massachusetts were compelled to begin the cleanup of Boston Harbor by rapidly and radically improving the existing inadequate sewage collection, treatment, and disposal system that had suffered under decades of neglect. By 1988 the MWRA had received the necessary federal permits to begin the process.
The Boston Harbor Project, the ongoing outcome of the federal suit, represents one of the largest and most expensive ($3.7 billion) projects of its kind in the world. The extent of this undertaking should not be surprising. The MWRA services over 2.5 million people and 5,500 businesses in the 43 communities in the metropolitan Boston area. The system handles an average of over 450 million gallons of sewage a dayÑall of which is released into Boston Harbor.
By 1992 major releases of scumÑfloatable pollution composed primarily of grease, oil, and plastic materialsÑhad been largely controlled. The practice of releasing sewage sludge into the harbor had been stopped. The sludge is now reduced in volume in a series of huge concrete, egg-shaped structures. Twelve of these anaerobic sludge digesters are the most prominent feature on the Deer Island treatment works. The digestion processes produces methane gas which is captured and used as an energy resource. The digested biosolids are removed and barged across Boston Harbor to a facility where they are converted into organic-rich pellets that are sold as agricultural fertilizer.
The Boston Harbor Project also includes modernization and expansion of the Deer Island treatment facility; construction of an eleven-foot diameter tunnel under Boston Harbor to transport sewage currently treated at the Nut Island treatment plant to the new plant on Deer Island; and construction of a 9.5-mile long, 24-foot diameter tunnel to completely remove the Deer Island effluent from Boston Harbor and discharge it farther offshore in Massachusetts Bay. In addition to the Boston Harbor Project, the MWRA has undertaken associated projects to control combined sewer overflows (CSO's) and to reduce toxic materials that enter the sewer system.
By 1996 the combination of improved primary treatment at Deer Island and the diversion of sludge discharges had reduced the amount of solids released into the harbor to 60 tons/days. As a result of these and other enhancements, the condition of the Harbor has improved remarkably. Bacterial counts that indicate the possible presence of human water-borne pathogens have been reduced; the frequency of closures of harbor beaches has been reduced; PCB (polychlorinated biphenyls) concentrations in lobsters from Boston Harbor have declined; concentrations of toxic heavy metals at the surface of sediments on the bottom of Boston Harbor have declined; the frequency of liver tumors in winter flounder from the harbor have declined; the clarity of harbor water has improved; and the abundance of a bottom-dwelling crustacean, the amphipod, Ampelisca, has increased dramatically.
More dramatically, these water quality improvements have increased people's use of the harbor as their perception of its environmental quality has improved. The increased water quality has sparked renewed interest in the many islands that are part of Boston Harbor. In 1997 these islands were designated as a National Recreational Area by the U.S. National Park Service.
The efforts to clean up Boston Harbor have not been without controversy. Because the Commonwealth of Massachusetts delayed improvements to the Deer Island facility for so long, federal funds that had been available in the 1970's and early 1980's to help support treatment plant upgrades had been discontinued. Thus, the sewer users in the MWRA region have borne the majority of the costs of the Boston Harbor Project. While this situation has caused their sewer and water fees to increase dramatically (in some cases by a factor of four from 1985 to 1996), many argue that it is appropriate that the users should pay rather than having the Project's costs subsidized by taxes across a broader constituency that do not use the MWRA system.
Another significant controversy in the Boston Harbor Project is associated with the ultimate fate of the MWRA sewage effluent. The construction of the "pipe," the 9.5-mile tunnel under the bottom of Massachusetts Bay will move the release point of MWRA sewage from Boston Harbor into Massachusetts Bay where it will receive much greater dilution. The outfall itself will be fifty-five 100-ft high riser-diffusers spaced along the last 1.25 miles of the tunnel in 250-ft deep water.
Concerns have been raised that introducing this effluent into Massachusetts Bay will have significant negative impacts on that ecosystem, as well as on adjacent Cape Cod Bay and Stellwagen Bank, the site of a National Marine Sanctuary. Potential environment effects of the effluent include nutrient enrichment resulting in increased phytoplankton growth, including toxic red tides; bacterial contamination of shellfish; and increased inputs of toxic materials into the Bays. Particular concern over the possible impacts to endangered right whales which use Stellwagen Bank have been voiced.
To try to allay the concerns over potential outfall pipe impacts, the MWRA and other agencies have initiated an extensive monitoring and modeling program of Massachusetts Bay. Additionally the MWRA has established an "Outfall Contingency Plan" that addresses responses that will be made if adverse changes in certain environmental monitoring "trigger parameters" are detected. The outcome of outfall effects and the suitability of this contingency plan will only be known once the outfall is activated in 1998.
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