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EPA and DEP Allow Changes for Plan to Manage Discharge from Deer Island

Release Date: 04/03/2001
Contact Information: Amy Miller, EPA Press Office (617-918-1042)

BOSTON - The U.S. Environmental Protection Agency and the Massachusetts Department of Environmental Protection agreed today to allow In a letter to MWRA issued this week, EPA New England and DEP said they will revise the allowable levels of four indicators of pollution in the bays: floating materials in the wastewater discharges; nuisance algae in the Massachusetts Bay near the end of the outfall tunnel where the wastewater is discharged; small bottom-dwelling animals near the discharge point; and small animals called zooplankton in Massachusetts and Cape Cod bays.

"The contingency plan, which is attached to MWRA's discharge permit, can be changed yearly to ensure that the MWRA remains responsive in its monitoring based on the best available science," said Ira Leighton, acting regional administrator for EPA's New England office. "The changes we are allowing this year continue our efforts to make sure that discharge from Deer Island are not detrimental to the marine life and water quality of Massachusetts and Cape Cod bays."

EPA and DEP last year granted MWRA permission to open the 9.5-mile outfall tunnel that discharges treated wastewater from Deer Island into Massachusetts Bay. Activating the outfall tunnel was one of the final pieces of a 15-year effort by state and federal environmental agencies, the MWRA and other groups to bring about the restoration of Boston Harbor and Massachusetts Bay.

The Deer Island Treatment Plant treats wastewater from Boston and 42 other eastern Massachusetts communities. The plant's discharge permit sets stringent limits on pollutants to be discharged. In addition to the contingency plan and a companion water monitoring plan, it includes extensive water conservation and pollution prevention requirements.

This is the first time the EPA has required such a contingency plan in issuing a discharge permit. The contingency plan establishes "caution" and "warning" levels for a range of environmental indicators. If the effluent reaches warning levels, prompt action is required unless there is convincing evidence that the discharge is not contributing to an environmental problem. Although the MWRA requested changes to the contingency plan, it did not propose any reductions to the monitoring plan.

In October 2000, MWRA asked that certain of these pollution-indicator levels be changed, as well as the procedures for monitoring them. In the letter issued this week, EPA New England and DEP – in consultation with the Outfall Monitoring Science Advisory Panel, as well as the public – agreed to certain changes, suggested others, and rejected still others. In particular, EPA New England and DEP said:

    • MWRA should videotape the amount of floating material in the discharge that escapes from the treatment plant, and should improve maintenance and operations of the equipment used to remove the floating solids. EPA and DEP agreed with the MWRA that there is no way to monitor the absolute quantity of floating solids released under the existing system.
    • Allowed an increase in the allowable level of nuisance algae that may be found in the waters, agreeing with MWRA that the original threshold was too low, and not calculated appropriately. Because nuisance algae are monitored on a regular basis, EPA and DEP rejected MWRA's request to remove the threshold entirely.
    • Agreed to tighten the acceptable amount of those bottom-dwelling animals that indicate pollution. The MWRA had requested this change, noting that the earlier levels were so high that they would never be exceeded.
    • Agreed with MWRA to eliminate the levels set for the types and amount of zooplankton measured in the bays. EPA and DEP agreed that too many other factors may come into play in the levels of zooplankton measured in the bay. The federal and state agencies said that MWRA must continue to monitor these tiny animals, report on changes and research the factors affecting the presence of zooplankton in Massachusetts and Cape Cod bays.
For more information on the Deer Island Treatment Plant discharge permit and monitoring plan, go to, or