OMSAP Public Meeting September 1999 Water Quality Monitoring Program and Baseline Results OMSAP Technical Meeting September 22, 1999 Carlton D. Hunt & P. Scott Libby Battelle Duxbury Operations Duxbury, MA 02332

OMSAP Public Meeting September 1999 Acknowledgements n Numerous scientists, regulators, and citizens from the New England area have contributed to the design, implementation, interpretation and understanding of water quality in the Massachusetts Bay system Siting studies Research Monitoring n Products of this work are included in over 20 major water quality reports available from MWRA at and numerous peer reviewed publications

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

OMSAP Public Meeting September 1999 Presentation Summary n Overview n Water Quality Monitoring Program n Major Baseline Characteristics n Spatial and Temporal Responses Nutrients Chlorophyll Dissolved Oxygen Plankton n Thresholds n Future expectations

OMSAP Public Meeting September 1999 n Nutrients, dissolved oxygen, or phytoplankton biomass n Phytoplankton and zooplankton community composition in the nearfield and farfield occur n Phytoplankton production rates in the water column near the outfall and outer Boston Harbor Water Quality MonitoringIntroduction WQ monitoring program objectives are to determine if changes occur in the nearfield (local) or farfield (regional) to

OMSAP Public Meeting September 1999 Water Quality Monitoring Overview n Nutrients, chlorophyll, and dissolved oxygen n Harbor signatures and gradients in Mass Bay n Plankton communities n Thresholds and detection of change n Expectations of conditions after the outfall begins discharging at the Massachusetts Bay location This presentation focuses on spatial and temporal responses in the following areas

OMSAP Public Meeting September 1999 MWRA Monitors 21 Nearfield and 28 Farfield Water Quality Stations in Massachusetts Bay Water Quality Measurement Program

OMSAP Public Meeting September 1999 Water Quality Monitoring Vertical profiles n Continuous vertical hydrographic profiles to within 5 m of the bottom Temperature Salinity Dissolved oxygen Chlorophyll fluorescence Beam attenuation (particles) Irradiance (light) n Discrete samples from 3 or 5 depths (depending on water depth)

OMSAP Public Meeting September 1999 Water Quality Monitoring Parameters Measured

OMSAP Public Meeting September 1999 Water Quality Monitoring Parameters Measured

OMSAP Public Meeting September 1999 Water Quality Monitoring Data evaluation To understand spatial and temporal trends and causal relationships Hydrographic Response to weather (wind and rain) Light fields Phytoplankton Chlorophyll biomass Species composition Nuisance species Nutrients Plankton responses Primary production Zooplankton Species composition Dissolved Oxygen Production /Respiration

OMSAP Public Meeting September 1999 Water Quality Baseline Characteristics n Gradients (nutrients, biomass, and dissolved oxygen) Temporal Offshore Vertical n Tidal exchange and export from Boston Harbor n Plankton Communities Phytoplankton Zooplankton

OMSAP Public Meeting September 1999 Water Quality Gradients n Gradients in the system are examined using horizontal contours vertical sections temporal plots –individual stations –regions in the Bay

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients n The gradient offshore of Boston Harbor and along the shore from the Harbor to Plymouth is a persistent feature in the surface waters under the present discharge regime.

OMSAP Public Meeting September 1999 Water Quality Temporal Responses Nitrate

OMSAP Public Meeting September 1999 Water Quality Temporal Responses Silicate

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients Surface Salinity

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients June 1998 Storm Response Surface Salinity

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients Surface Temperature

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients Surface DIN

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients Surface Silicate

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients Surface Chlorophyll

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients Bottom Dissolved Oxygen

OMSAP Public Meeting September 1999 Water Quality Horizontal Gradients Surface Ammonia

OMSAP Public Meeting September 1999 Water Quality Harbor Gradient after Secondary Treatment - NH 4

OMSAP Public Meeting September 1999 Water Quality Harbor Gradient after secondary treatment - NH 4

OMSAP Public Meeting September 1999 Water Quality Vertical Gradients Boston to GOM Transect - Salinity

OMSAP Public Meeting September 1999 Water Quality Vertical Gradients Boston to GOM Transect - Temperature

OMSAP Public Meeting September 1999 Water Quality Vertical Gradients Boston to GOM Transect - DIN

OMSAP Public Meeting September 1999 Water Quality Vertical Gradients Boston to GOM Transect - Silicate

OMSAP Public Meeting September 1999 Water Quality Vertical Gradients Boston to GOM Transect - Chlorophyll

OMSAP Public Meeting September 1999 Water Quality Vertical Gradients Boston to GOM Transect - Dissolved Oxygen

OMSAP Public Meeting September 1999 Water Quality Summary Vertical & Horizontal Gradients n Water column is well mixed over the winter n Increasing temperature and runoff in early spring initiates stratification n Spring/summer temperature differences intensify stratification n Stratification remains until fall overturn (due to lower vertical temp gradient and increased storm activity) n Return to winter conditions in early winter

OMSAP Public Meeting September 1999 Water Quality Summary Vertical & Horizontal Gradients n Boston Harbor is localized source of nutrients Sewage effluent comprises 90% of the land source nutrients added to Boston Harbor (Kelly 1997) n Strong inshore/offshore nutrient gradient away from Harbor in surface waters n Gradients are less distinct in the bottom waters n Seasonal nutrients cycle (stratification) n Upwelling and winds may be a factor in bringing nutrients to surface waters in the summer

OMSAP Public Meeting September 1999 Water Quality Harbor/Nearfield Exchange A strong physical front is evident off the mouth of Boston Harbor Front analysis

OMSAP Public Meeting September 1999 Water Quality Harbor/Nearfield Exchange outfall

OMSAP Public Meeting September 1999 Water Quality Harbor/Nearfield Exchange

OMSAP Public Meeting September 1999 Water Quality Harbor/Nearfield Exchange From Kelly N TN (4.5 DIN) 0.2 TN1.7 DIN TN (11-12 DIN) ~15 TN ( DIN) < N TN <0.2 TN<1.7 DIN TN ( DIN) Baseline PeriodPost-Discharge Period 85% of the nutrients from the Deer Island outfall are currently exported into Massachusetts Bay 100% of the nutrients from the Deer Island outfall will be exported into Massachusetts Bay in the future Units are in 10 5 kmols/yr Freshwater Ocean exchange Ocean exchange dominates the nutrients mass balance in Boston Harbor

OMSAP Public Meeting September 1999 Water Quality Summary Harbor Exchange n Effluent from Deer Island outfall presently enters Massachusetts Bay n Exchange of Boston Harbor waters with nearfield and coastal waters results in a plume of Harbor water extending southward along the coast in western Massachusetts Bay n Harbor plume is primarily in the western nearfield surface waters and coastal waters to the south

OMSAP Public Meeting September 1999 Water Quality Regional Responses n Stations in six regions are examined for temporal and spatial responses Boston Harbor Coastal Nearfield Cape Cod Bay Boundary with Gulf of Maine Offshore (south and east of the nearfield)

OMSAP Public Meeting September 1999 Water Quality Chlorophyll n An indicator of phytoplankton biomass n Key measurement and indicator in the water quality program n Temporal and regional distribution are variable n Responds to light and nutrient fields (see Keller et al. Poster) Summer surface water nutrient limitation Winter light limitation Influenced by weather and storm events n Results in a generally consistent seasonal progression n Maximum values are in the pycnocline during stratification and in the waters of the western nearfield and outer Boston Harbor

OMSAP Public Meeting September 1999 Water Quality Chlorophyll Distribution n Seasonal peaks are observed in the spring, summer, and fall n Classic winter/spring bloom does not always occur n Frequently observe a major fall boom n Large sustained bloom occurred in the winter/spring of 1999 following a late winter bloom in December 1998 Asterionellopsis glacialis Phaeocystis pouchetii

OMSAP Public Meeting September 1999 Water Quality Nearfield Chlorophyll - Fall Blooms

OMSAP Public Meeting September 1999 Water Quality Nearfield Chlorophyll - Spring Blooms

OMSAP Public Meeting September 1999 Water Quality Nearfield Chlorophyll Winter Bloom Nearfield Chlorophyll Satellite imagery suggests chlorophyll levels in the surface waters of Massachusetts Bay remained elevated between mid-Dec 1998 and early February 1999

OMSAP Public Meeting September 1999 Water Quality Annual Chlorophyll Data

OMSAP Public Meeting September 1999 Water Quality Seasonal Chlorophyll Data

OMSAP Public Meeting September 1999 Water Quality Chlorophyll Summary n Spring bloom not as consistent as conventional wisdom would suggest n Fall bloom appears to be a consistent event n having occurred in 5 of 7 years n Elevated summer concentrations observed in Nearfield (98 & 99)

OMSAP Public Meeting September 1999 Water Quality Dissolved Oxygen n Degradation of particulate organic matter (POM) water column deposited POM in sediments n Other factors duration and strength of stratification bottom water temperature initial DO concentration at onset stratification downwelling/intrusion events Many factors affect dissolved oxygen levels in the water

OMSAP Public Meeting September 1999 Water Quality Dissolved Oxygen n Mean DO in bottom waters has exceeded the caution level once n 1999 may have an exceedance in September or October

OMSAP Public Meeting September 1999 Water Quality Nearfield Bottom Water DO Distribution September 8,1999 n Nearfield DO Thresholds (as a survey mean) Caution = 6.5 mg/L Warning = 6.0 mg/L n Survey Mean 6.66 mg/L n Western Nearfield DO <6.0 mg/L n Eastern Nearfield DO >7.0 mg/L

OMSAP Public Meeting September 1999 Water Quality Nearfield Surface and Bottom Water DO Distribution September 8,1999 n Surface DO shows a maximum in the western nearfield n Note contour interval change from the bottom DO image in the pervious slide to place both images on the same color scale Surface Bottom

OMSAP Public Meeting September 1999 Water Quality Seasonal DO Decline Nearfield The rate of decline in the near bottom water DO is relatively constant in the Nearfield

OMSAP Public Meeting September 1999 Water Quality Seasonal DO Decline Stellwagen Basin The rate of decline in the near bottom DO in Stellwagen Basin during stratification is also relatively constant

OMSAP Public Meeting September 1999 Water Quality Seasonal DO Decline Nearfield The correspondence between the minimum DO in the Nearfield and in Stellwagen Basin provides a reasonable predictor of the DO in Stellwagen Basin bottom waters

OMSAP Public Meeting September 1999 Water Quality Baseline Characteristics n Gradients (Nutrients, biomass, and dissolved oxygen) Temporal Offshore Vertical n Tidal exchange and export from Boston Harbor n Plankton Communities Phytoplankton Zooplankton

OMSAP Public Meeting September 1999 Water Quality Plankton Species n Phytoplankton Abundance by species or group Key taxa –Diatomsa –Microflagelates –Dinoflagelates –Cryptomonad –Nuisance species - Alexandrium tamerenses - Phaeocystis pouchetii - Pseudo-nitzschia multiseries n Zooplankton/Meroplankton Abundance by species, group or stage (adult, copepodite, nauplii) Key taxa – Acartia spp. – Oithona spp. – Calanus spp. – Pseudocalanus spp. – Centropages spp. –Polychaete spp. –Mollusca Gastropoda; Bivalvia –Pteropoda spp. –Opisthobranchia spp. –Cirripedia spp

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Variability n Phytoplankton abundance in the nearfield generally ranges between a few thousand to 2 million cells/ L n Abundance can range to over 12 million cells/L n Range for individual samples can be large for any given survey n Reflects variability between surface and pycnocline samples

OMSAP Public Meeting September 1999 Water Quality Total Phytoplankton Inter-annual and Regional Comparison n Phytoplankton abundance in the farfield areas is generally similar to the nearfield n Occasionally abundance in CCB and the Harbor are larger on average than in the nearfield n Abundance at the boundary Station F27 are lower on occasion n Seasonal patterns are variable although late summer and fall peaks are frequent

OMSAP Public Meeting September 1999 Water Quality Diatoms n Diatom abundance in the nearfield generally ranges between a few thousand to 1 million cells/ L n Occasionally abundance can range to over 12 million cells/L n Range reflects within survey variability n Seasonal patterns are variable and no one year exactly replicates another

OMSAP Public Meeting September 1999 Water Quality Diatoms n Diatom abundance in the farfield areas is generally similar to the nearfield n Abundances in CCB range higher and lower than in the nearfield and the timing of blooms is often different than the nearfield n Abundance at the boundary Station F27 are lower n Coastal stations and Harbor abundance are often similar n Seasonal diatom abundance is clearly evident but varies in magnitude and timing

OMSAP Public Meeting September 1999 Water Quality Microflagellates n Microflagellate abundance in the nearfield generally ranges between a few thousand to 1 million cells/ L n Occasionally abundance can range to over 12 million cells/L n Range reflects within survey variability n Seasonal abundance patterns are variable and no one year exactly replicates another

OMSAP Public Meeting September 1999 Water Quality Microflagellates n Abundance in the farfield areas is very similar to the nearfield n Abundances in CCB and Harbor are occasionally higher than in the nearfield and the timing of blooms is often different n Seasonal abundance is clearly evident and peaks in the late summer

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Community Composition

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Community Carbon-based composition n Concerns over carbon cycling and outfall effects on the major taxa in the Bay have resulted in comparison of the phytoplankton community abundance on a carbon basis n Each species is assigned a carbon per cell value and the carbon-based abundance is calculated from abundance and carbon value n The total phytoplankton carbon in the sample is then calculated by summing the various species n Data presentations are developed as shown for the cell abundance data n Focus is on the relative proportions of diatiom carbon and microflagellate carbon

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Community Carbon-based composition n Patterns in total carbon based abundance are similar to the cell based abundance n Survey means show distinct temporal patterns n Within survey and sample variability is high.

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Community Carbon-based composition

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Community Carbon-based composition

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Community Nuisance Species COMPARISON OF SEASONAL NUISANCE SPECIES DATA Species95 th Percentile cells/L nBaseline condition Alexandrium tamerensesWinter-Spring: 0.27 Summer: 5.00 Fall: Non zero counts in 31 of 1,156 samples Phaeocystis pouchetiiWinter-Spring: Summer: Fall: Non zero counts in 93 of 1,122 samples Pseudo-nitzschia multiseries a Seasonal (Winter-Spring, Summer, Fall) mean concentration of confirmed speciesexceed 500,000 cells/L Pseudo-nitzschia pungens Non zero counts in 438 of 1,122 samples 1999To be added to the estimate of the 95 th percentile a Pseudo-nitzschia pungens counts will trigger a SEM confirmation ofP. multiseries

OMSAP Public Meeting September 1999 Water Quality Phytoplankton Community Summary n Species composition is generally similar among samples from within surveys and among regions n Total abundance varies among samples, survey, season, and regions n Distinct temporal patterns are evident, although variability within surveys is high n Diatoms and microflagellates are the numerically dominant plankton groups n Carbon-based abundance is dominated by diatoms n Nuisance species are present sporadically and at low levels n Blooms of Phaeocystis pouchetii have occurred twice during the baseline, once in the spring of the year and once in the fall of the year n Alexandrium tamerenses blooms have not occurred since 1993 (see Keefer and Anderson poster) although species are occasionally observed in low abundance n Massachusetts Bay communities are consistent with broader-scale zooplankton distributions in the Gulf of Maine and Buzzards Bay (see Turner poster)

OMSAP Public Meeting September 1999 Water Quality Zooplankton Variability n Zooplankton abundance in the nearfield ranges between a few thousand to 100,000 individuals/ L n Occasionally abundance can range to 150K individuals/L n The range among individual samples is large for any give survey n Total abundance appears increase since 1994

OMSAP Public Meeting September 1999 Water Quality Total Zooplankton Inter-annual and Regional Comparison n Total zooplankton abundance in the farfield regions are generally similar to the nearfield n Total abundance is often lower in Boston Harbor relative to Massachusetts Bay n The general increase in nearfield total abundance since 1994 is reflected in the other offshore regions

OMSAP Public Meeting September 1999 Water Quality Total Zooplankton Copepod Abundance n Adult and copepodite stages of the non- Acartia spp. copepods show a clear seasonal pattern n Abundance is generally similar throughout the Bay n Lower abundances are observed in Boston Harbor n Cape Cod Bay and the nearfield are generally similar n The highest baseline abundance since 1992 were recorded in the winter/spring of 1999 Oithona spp., Calanus, Pseudocalanus, and Centropages spp.

OMSAP Public Meeting September 1999 Water Quality Total Zooplankton Meroplankton Abundance n Meroplankton form minor component of the zooplankton community n The Harbor, CCB, and Coastal abundance in the winter spring of 1999 were the highest observed during the baseline Polychaete spp.; Gastropoda; mollusca, bivalvia spp.; Cirripedia spp

OMSAP Public Meeting September 1999 Water Quality Acartia spp. Abundance n Acartia spp. abundance is higher in the Harbor compared to the nearfield n Seasonal patterns (summer maximum) in the Harbor abundance are evident

OMSAP Public Meeting September 1999 Water Quality Draft Zooplankton Threshold

OMSAP Public Meeting September 1999 Water Quality Zooplankton Community Summary n Community composition among samples from a survey, within seasons, or among farfield regions are generally similar n Abundance varies among samples, survey, season, and regions n Although variability within surveys is high distinct temporal patterns are evident in the data n Massachusetts Bay communities are consistent with broader scale zooplankton distributions in the Gulf of Maine and Buzzards Bay ( see Turner poster )

OMSAP Public Meeting September 1999 Water Quality Baseline Monitoring Summary n Baseline data indicate that water parameters are highly variable in the nearfield (esp. western nearfield) n Seasonal and inter-annual variability n Inshore/offshore gradients in nutrients, chlorophyll, and DO n Plankton populations are similar offshore; Harbor differences are event relative to offshore populations and abundance n Plankton respond in a relatively predictable manner in this system n Ability of the monitoring program to detect change before any given threshold is reached is high

OMSAP Public Meeting September 1999 Expectations of changes in water quality after transfer to Massachusetts Bay n Harbor Response Nutrients field in the outer Harbor will decrease in concentration and extent Chlorophyll levels will decrease in the Harbor and western nearfield Abundance of offshore zooplankton in the outer Harbor may increase if salinity increases Phytoplankton species composition remain similar to those present now Because the new outfall relocates the current discharge to a deeper depth that is generally below the photic zone and will achieve much higher dilution than is currently achieved at the Deer Island outfall, the net ecological impact is likely to be small and limited to the nearfield.

OMSAP Public Meeting September 1999 Expectations of changes in water quality after transfer to Massachusetts Bay n Massachusetts Bay Response total nutrient fields are not expected to change appreciably in the vicinity of the outfall, although a nutrient signal against a lower offshore background especially for NH 4 may be observed –Plume tracking and nearfield monitoring will evaluate this Coastal plume will be less distinct and less intense Chlorophyll levels will decrease in surface waters of the western nearfield Little or no change in the zooplankton community composition or abundance Phytoplankton species composition will see little or no change Bottom water DO values are not expected to change substantially relative to the current baseline history