and Massachusetts Bay
MWRA developed a Contingency Plan to
ensure that discharge from the Bay outfall does not result in adverse impacts.
The Plan identifies thresholds that can suggest that effluent quality
or conditions in the Bay may be changing. When monitoring indicates that
"Caution" or "Warning" threshold levels for certain environmental indicators are
exceeded, these exceedance reports must be posted
on this website.
MWRA has earned a Platinum 7 Peak Performance award from the National Association of Clean Water Agencies in recognition of the Deer Island Treatment Plant having 100% compliance with its National Pollutant discharge Elimination System permit for 7 consecutive years through 2013
Contingency Plan (PDF)
Contingency Plan Reports:
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 the
Plan Quarterly Report on Effluent Monitoring
Summary of data on pH, fecal coliform, toxicity, oil and grease, and nitrogen
in Deer Island Treatment Plant effluent (treated wastewater) compared
with threshold limits in the Contingency Plan.
The annual outfall monitoring overview presents monitoring program results for
effluent and field data. It compares all results to Contingency Plan thresholds.
A review of zooplankton
communities in the Massachusetts Bay/Cape Cod Bay system
The MWRA must report on the results of special zooplankton studies and
evaluate whether a scientifically valid zooplankton community threshold
could be developed. (PDF 222 KB)
Project Plan for Nitrogen Monitoring in
Deer Island Treatment Plan Waste Streams
A plan to facilitate the selection of nitrogen removal technology. (PDF
Proposed Modifications to the
Contingency Plan (November 2001)
Proposed Contingency Plan threshold modifications to dissolved oxygen
concentration, dissolved oxygen saturation, and Alexandrium abundance.
(See previous modification request)
Dissolved oxygen background calculation
Explanation of statistical approach to calculation of dissolved oxygen
"background conditions" in support of proposed Contingency Plan
Outfall Contingency Simulation: Treatment
Plant Chlorination Upset and Red Tide
Simulates the notification and decision-making processes that would occur
in the event of unexpected problems at the treatment facility or in Massachusetts
Many of our reports are in PDF format, which requires Adobe Acrobat
Reader®, a free program available from Adobe
Systems. To request a paper copy of any report, please contact
the MWRA Environmental Quality Department at 617-788-4601, or e-mail
us at firstname.lastname@example.org.