The MWRA outfall monitoring program. What we measure and what we have observed so far.

Part 1. What we are monitoring. Objectives: test for compliance with the Permit test for exceedance of contingency plan thresholds test whether environmental changes are greater than expected

Effluent pathogen indicators residual chlorine total suspended solids biochemical oxygen demand toxicity testing PCBs flow pH nitrogen loading numerous organic and inorganic contaminants

Water column nutrients chlorophyll dissolved oxygen temperature, salinity light, water clarity solids phytoplankton nuisance and noxious algae zooplankton photosynthesis, respiration remote sensing, moored instruments marine mammal observations bacterial indicators, viruses diffuser mixing

21 nearfield sites (in a grid near outfall site) 28 farfield sites (distant from the outfall site) 17 nearfield, 6 farfield surveys each year

1998 Whale sightings during MWRA surveys

1999

2000

Sediments soft bottom community structure rock cobble communities sediment oxygen toxic metal and organic chemicals sediment bulk characteristics chemistry, tracers nutrient and oxygen flux

Sample locations for soft-bottom communities

Fish and Shellfish metals and organic chemicals, including pesticides and PCBs in flounder and lobster bioaccumulation of toxic chemicals in transplanted mussels liver disease in flounder

Mussels: collection and deployment locations

Part 2. What we have seen since the outfall was relocated. MWRA response to exceedances.

In summer, the effluent discharged at the Massachusetts Bay outfall is trapped beneath the thermocline

October 1999 Ammonium concentration (NH4 + uM) Boston nearfield Cape Ann October 2000

Ongoing Monitoring Data reported to MWRA Threshold Exceeded? NO YES Annual Monitoring Report Nov 15 Notify: DITP Regulatory agencies OMSAP Public (web and libraries) 5 days Threshold Level Caution Warning Adjust operations if needed Review supporting data Collect additional data if needed < 90 days Evaluate MWRA contribution w OMSAP and regulators Plan/schedule to address MWRA impacts Report every 30 days to regulators, public on evaluations, action and follow-up Adverse impact? YES NO Quarterly Wastewater Performance Reports Evaluations, actions and follow-up

Contingency Plan threshold exceedances for 2000 Chlorine too high in treatment plant on 12/15/00. Control equipment installed. pH too low in treatment plant on 12/7/00. Artifact of sampling procedure. High chlorophyll in autumn A regional event. Low DO saturation in bottom waters in October Recognition of natural phenomena in revising the threshold.

Chlorophyll threshold exceedance autumn 2000

Areal Chlorophyll (mg per square meter) September

Satellite images of chlorophyll, averaged by month J. Yoder 1, J.O’Reilly 2, S.Schollaert 1, T. Ducas 2 1 URI,GSO, 2 NOAA, NMFS October September

Harmful algal blooms in Massachusetts Bay Paralytic Shellfish Poisoning (PSP)Alexandrium Noxious blooms (aesthetics) Phaeocystis Amnesic Shellfish Poisoning (ASP)Pseudo-nitzschia

Alexandrium (cells/L) Phaeocystis (million cells/L) Pseudo-nitzschia (million cells/L)

Dissolved oxygen in bottom waters of the nearfield DO concentration (mg/L) DO saturation (percent)

90-second animation of the rocky-bottom video survey in July 2001 in the nearfield

The region surrounding the Massachusetts Bay Outfall site consists of a series of ridges and valleys.

Vertical Exaggeration 12X