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
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