The Utility of the Bays Eutrophication Model in

The Utility of the Bays Eutrophication Model in the Harbor Outfall Monitoring Program James Fitzpatrick Hydro. Qual, Inc. September 22, 1999 OMSAP Public Meeting September 1999

Objectives of Water Quality Modeling n Define Cause and Effect Relationships n Define Impacts of Pollutant Sources n Assess Required Levels of Control n Evaluate Planning Alternatives for Water Quality Management n Focus Additional Monitoring and Research Needs n Assess Future Water Quality Conditions OMSAP Public Meeting September 1999

Concerns Ecological Nutrients Contaminants Organic Material Food Chain Community Structure Living Resources Human Health Contaminants Bacteria Viruses Bioaccumulation Gas Exchange ATMOSPHERE Light WATER COLUMN N 2, | O 2, CO 2 Outflow Inflow Sources Rivers Boundary Nonpoint Effluents Planktivorous Fish Phytoplankton Dissolved Zooplankton Microbes Particulate Mammals Piscivorous Fish Demersal Fish Detritus Regeneration N, P, Si, O 2, CO 2 SEDIMENT Epibenthos Microbes Infauna

BEM Model Formulation OMSAP Public Meeting September 1999

BEM Model Chlorophyll Comparison 1992 -1994 Solid lines are the modeled response in Chlorophyll in the surface waters Open circles depict monitoring results OMSAP Public Meeting September 1999

BEM Model Carbon Particulate Organic Comparison 1992 - 1994 Solid lines are the modeled response in POC in the surface waters Open circles depict monitoring results OMSAP Public Meeting September 1999

BEM Model 1993 Fall Bloom Event Relationship among carbon, chlorophyll, and cell abundance during the Ocober 1993 Asterionellopsis Glacialis bloom OMSAP Public Meeting September 1999

Regional Primary Production 1993

BEM Model Comparison Dissolved Oxygen 1992 -1994 Solid lines are the modeled response in DO in the bottom waters Closed circles depict monitoring results OMSAP Public Meeting September 1999

BEM Model Comparison Temperature 1992 - 1994 Solid lines are the modeled response in temperature Closed circles depict bottom water monitoring results Open circles depict surface water monitoring results OMSAP Public Meeting September 1999

BEM Model Salinity Comparison 1992 -1993 Solid lines are the modeled response in salinity Closed circles depict bottom water monitoring results Open circles depict surface water monitoring results OMSAP Public Meeting September 1999

BEM Model 1994 DIN Comparison 1992 - Solid lines are the modeled DIN response Open circles depict surface water monitoring results OMSAP Public Meeting September 1999

BEM Model Demand Sediment Oxygen 1992 -1994 Solid lines are the modeled SOD at selected locations in Massachusetts Bay Closed circles depict monitoring results OMSAP Public Meeting September 1999

BEM Model Capability Mass Balance OMSAP Public Meeting September 1999

BEM Model Balance Nitrogen Mass OMSAP Public Meeting September 1999

BEM Model Effluent Influence Total Nitrogen - Deer Island Total N concentration (solid lines) resulting from the boundary condition and effluent discharged from Deer Island fraction contribution (dashed line) of MWRA effluent at various locations within Massachusetts Bay. OMSAP Public Meeting September 1999

BEM Model Outfall Effluent Influence Total Nitrogen - Mass Bay Projected total nitrogen concentration (solid lines) resulting from the boundary condition and effluent discharged from Deer Island fraction contribution (dashed line) of MWRA effluent at various locations within Massachusetts Bay. OMSAP Public Meeting September 1999

BEM Model Predictive Capability Distribution chlorophyll in surface waters under two nutrient loading regimes COL = Current outfall location FOL = Future outfall location OMSAP Public Meeting September 1999

BEM Model Compatibility to Measured Responses The BEM appears to capture a number of spatial and temporal features of water quality within the Bays during the 1992 -1994 time period, including: n n n the spatial decrease in phytoplankton biomass in Mass Bay as a function of distance from Boston Harbor the limitation of the winter/spring diatom bloom in Cape Cod Bay by silica the limitation of summer primary productivity by DIN the annual cycle of primary productivity in northwest Mass Bay OMSAP Public the annual cycle of DO, with minimum bottom Meeting water concentrations occurring in late September 1999

BEM Model Limitations The BEM was not able to fully reproduce two of the unique features of the 1992 -1994 data set: n n The Asterionellopsis glacialis bloom observed in the fall of 1993, • however, estimates of the magnitude of the bloom may be exaggerated due to low C: Chl-a ratios observed in the A. glacialis the minimum DO concentrations in the fall of 1994, • however, the model was able to compute minimum DO concentrations that were approximately 1 mg/L lower in the fall of 1994 as compared to 1992 OMSAP and. Public Meeting 1993 September 1999

BEM Model Utility n BEM is able to reproduce a number of the spatial and temporal features of water quality observed in the 1992 -1994 HOM data sets n BEM provides a tool with which to assess the relative importance of various nutrient inputs to the Mass Bays system n BEM provides a tool with which to assess the spatial and temporal effects of outfall relocation and increased nutrient inputs on primary productivity within the Mass Bays system n BEM can also suggest where additional monitoring and OMSAP Public field studies need to be performed (e. g. , open water Meeting boundaries and benthic primary productivity September 1999