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Department of Environmental Protection - Details - Proposed Extension to Alewife/Upper Mystic CSO Variance

CSO = Combined Sewer Overflow
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ONE WINTER STREET, BOSTON, MA 02108 617-292-5500




This information is available in alternate format by calling our ADA Coordinator at (617) 574-6872. DEP on the World Wide Web:
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The Department of Environmental Protection (DEP) hereby extends the Variance for CSO Discharges to the Alewife Brook/Upper Mystic River Basin from March 5, 2002 to September 5, 2003. This Variance extension, issued pursuant to the Massachusetts Surface Water Quality Standards at 314 CMR 4.00, allows CSO discharges from the outfalls along Alewife Brook/Upper Mystic River permitted to the Massachusetts Water Resources Authority (MWRA) and the Cities of Cambridge and Somerville, subject to specific conditions which follow, while providing time for DEP to obtain the information necessary to determine the appropriate water quality standard and level of CSO control for the watershed.

The Department grants this Variance extension based on its findings, as supported by the technical and cost information in the 1997 MWRA CSO Facilities Plan and the subsequent April 2001 MWRA Notice of Project Change (NPC), demonstrating that implementation of more stringent CSO controls at this time would result in substantial and widespread social and economic impact as specified in 314 CMR 4.03(4).

MWRA and the Cities of Cambridge and Somerville shall implement the revised recommended plan included in the April 2001 Notice of Project Change in place of the CSO abatement plan for the Alewife Brook/Upper Mystic Basin included in the approved 1997 MWRA CSO Facilities Plan. The implementation schedule will be as set forth in modifications to the Federal Court Order.

The Variance Extension becomes effective upon issuance and will be incorporated into the NPDES/MA permits for the MWRA and the Cities of Cambridge and Somerville, through modification or reissuance during the term of the Variance, with an additional opportunity for public comment. Failure by the MWRA and/or the Cities of Cambridge or Somerville to comply with the conditions of the Variance prior to permit modification or reissuance will constitute a violation of the existing permit, as well as the Massachusetts Surface Water Quality Standards.


All requirements and conditions of the March 5, 1999 Variance for CSO Discharges to the Alewife/Upper Mystic Basin remain in effect through the term of this Variance extension, subject to the exceptions and modifications which follow:

A. Actions to Minimize CSO/Sanitary Disharges

The following requirement replaces Section A.(1) in its entirety:

MWRA and the Cities of Cambridge and Somerville shall continue to implement the Nine Minimum Controls (NMC), monitor CSO activations and volumes, and implement the elements of the revised recommended plan included in the April 30, 2001 Notice of Project Change.

The NMC Reports were filed in 1997 and were largely based on EPA Guidance for Nine Minimum Controls (May 1995). Some of the information in these reports is somewhat dated and needs to be updated. Of particular concern is the nature and extent of the public notification requirements relative to CSO discharges and potential impacts

The public notification currently performed has included: posting of CSO outfalls; submitting NPDES reports and discharge monitoring reports; coordinating with Massachusetts Division of Marine Fisheries on impacts to shellfish resources; publishing and including on their website water quality information and annual reports from sampling programs; and publishing a CSO newsletter during the CSO planning process. Enhancements to the public notification practices are warranted for those most directly affected by CSO discharges.

By June 14, 2002, MWRA, in conjunction with the cities of Cambridge and Somerville, shall submit to DEP a workplan to provide improved public notification on the CSO discharges and potential impacts, and shall fully implement it once approved by DEP.
The following requirement is added to Section A.(2):

iv. By June 28, 2002 MWRA, in cooperation with the Cities of Cambridge and Somerville, shall provide to EPA and DEP a draft of an updated and expanded workplan to estimate CSO overflows for all remaining overflows covered by this Variance.

The final workplan shall be implemented by MWRA, Cambridge and Somerville in accordance with the schedule included with DEP's approval of the final workplan.

The following requirement is added to Section A.(3):

MWRA shall continue to work with EPA, DEP and its member communities regarding the recommendations of the MWRA Regional Infiltration/Inflow Task Force to minimize the impacts of I/I flows, and, where possible, identify opportunities for I/I removal in the upstream separate sewer systems which may further mitigate CSO discharges.

B. Actions to Further Assess CSO/Stormwater Pollutant Loads

(2) Stormwater Sampling is modified as follows:

The approved locations for stormwater monitoring were based on a number of factors including volume of the discharge and types of land use. The limited sampling has shown that there appear to be sanitary influences at a number of these outfalls. DEP will work with MWRA, Cambridge and Somerville and others to determine if substitute stormwater outfalls are more appropriate for characterization of stormwater loads within the watershed.

MWRA and the Cities of Cambridge and Somerville shall continue to conduct semiannual stormwater sampling as per section B.(2). of the Variance, utilizing the locations and the procedures established in a revised sampling program to be developed among the parties and approved by DEP. MWRA and the cities of Cambridge and Somerville shall submit a workplan identifying the stormwater sampling locations by July 1, 2002. The revised sampling locations shall be included in the Fall 2002 sampling run and for each subsequent sampling event thereafter during the course of this Variance.

A new requirement is added to this section:

(3) CSO Sampling

The sampling to characterize CSO pollutant loads in support of the 1997 CSO Facilities Plan included limited sampling of CSOs in the Alewife Brook watershed. Although many CSO samples were collected for the overall planning effort, no samples were collected from the facilities which presently discharge CSO to Alewife Brook. MWRA is therefore required to conduct representative sampling at two CSO locations during two separate CSO activation events to provide additional data to support the CSO loading analysis to be included in the Final CSO Reassessment. MWRA shall provide a workplan to DEP for conducting this sampling by July 1, 2002.

C. Assessment of CSO Controls in the Alewife/Upper Mystic Basin

The submission date for Variance Condition C.(1) is revised from January 1, 2002 to July 1, 2003. A scope of work for the effort shall be submitted by MWRA to DEP and EPA by September 1, 2002 for review and approval.

Items (1) i through iv are replaced by the following:

i. a description of the combined sewer systems in Cambridge and Somerville, and other associated interceptors and sewer system facilities.

ii. a reassessment of the recommended CSO abatement plan in the Alewife/Upper Mystic Basin and alternatives representing higher levels of CSO control, up to and including elimination. The reassessment must include: an analysis of the CSO, stormwater, and upstream pollutant loads of the alternatives; predictive modeling to estimate the water quality benefits of the CSO abatement alternatives; measures to be taken to minimize CSOs and mitigate impacts of any CSO discharges which will not be eliminated; and the costs of the alternatives.

iii. a final recommended plan for CSO abatement in the Alewife/Upper Mystic Basin, which shall comply with state and federal CSO policies.

iv. a description of the financial impact of the recommended CSO abatement plan, developed pursuant to EPA Guidance.

Future DEP Administrative/Regulatory Actions Regarding Variance
(1) DEP will hold a Public Forum during the MEPA comment period related to Condition C.(1) (estimated to be mid-July 2003) for MWRA to present to interested parties the results of reports and assessments.

(2) DEP will hold a Public Hearing once the Department issues a Tentative Decision on the Water Quality Determination for the entire Alewife Brook/Upper Mystic River Basin. This will allow another opportunity for all interested parties to provide input to EPA and DEP on the Proposed Level of CSO Control for the Basin. This Hearing will likely be held in early September 2003.

Please contact Steven G. Lipman, Department of Environmental Protection, 6th floor, One Winter Street, Boston, MA 02108 or by telephone at (617) 292-5698 if you have questions regarding this determination.


Glenn S. Haas
Division of Watershed Management

Contact the Alewife Study Group, North Cambridge Massachusetts, by email at