Ambient Monitoring

MWRA monitors water quality at the outfall location in Massachusetts Bay where treated sewage, or effluent, is discharged. This sampling program is termed Ambient Monitoring, because sampling is focused on the ambient, or surrounding waters at the outfall. More distant locations are also sampled in Massachusetts and Cape Cod Bays. Many ambient monitoring reports are sent for review to the Outfall Monitoring Science Advisory Panel (OMSAP). These and other reports can be accessed from MWRA's Technical Report List.

Ambient Monitoring Reports:

Bacteria Monitoring at the Outfall
Recent measure of sewage indicator bacteria, fecal coliform and Enterococcus, around the outfall and elsewhere in Massachusetts Bay.

Quarterly Ambient Monitoring Report
The results of all monitoring required by the ambient monitoring plan or the Bays Eutrophication Model must be reported quarterly to regulators, OMSAP, and the National Marine Fisheries Service.

Contingency Plan Quarterly Report on Ambient Monitoring
Data on mussel contamination, dissolved oxygen, and algae at sampling locations in Massachusetts Bay, compared with threshold limits in MWRA's Contingency Plan.

Ambient Monitoring Plan for the Massachusetts Water Resources Authority Effluent Outfall, Revision 1, March 2004
This is the final version of the first major revision to MWRA's Effluent Outfall Ambient Monitoring Plan.

Special Study of Flounder Skin Lesions
In the April 2003 flounder survey, an increased number of flounder ulcers were recorded, with the highest prevalence in Western Massachusetts Bay. The condition was absent from Eastern Cape Cod Bay. The Outfall Monitoring Science Advisory Panel recommended further study of this condition. MWRA designed a study to further investigate the possible causes of these ulcers.

Effluent Outfall Monitoring Plan
Any proposed changes to the Ambient (Outfall) Monitoring Plan must be submitted to state and federal regulators and OMSAP for review, and must be posted on this website. See all proposed changes to the plan below.

Proposed Changes to the Ambient Monitoring Plan:
June 2003
May 2003

Briefing for OMSAP Workshop on Ambient Monitoring Revisions-July 24, 2003

Briefing for OMSAP Workshop on Ambient Monitoring Revisions-June 18-19, 2003

Briefing for OMSAP Workshop on Ambient Monitoring Revisions-March 31-April 1, 2003

Bays Eutrophication Model (BEM): Modeling analysis for the period 1992-1994
MWRA must update, maintain, and run a three-dimensional water quality model called the "Bays Eutrophication Model" developed by Hydroqual and the United States Geological Survey. The model is designed to predict conditions caused by addition of nutrients to the bay, and is used to support decisions about nutrient limits in effluent discharges.

Outfall Maintenance and Diversion Plan  
This plan provides the protocol required to divert effluent flow in case MWRA is directed to temporarily shut down the exisiting outfall.

A review of issues related to the development of a food web model for important prey of endangered species in Massachusetts and Cape Cod Bays  
A review of the issues described below.