1. HARBOR UPDATE Transfer of Nut Island flows, and changes in the water quality of Boston Harbor David Taylor

2. 9 NITROGEN LOADINGS TO BOSTON HARBOR n Boston Harbor receives loadings of total nitrogen (TN) from terrestrial plus atmospheric sources of 6.6 x 10 5 kmol y -1 (Kelly 1998). n This is among the highest reported for any bay or estuary in the USA (Kelly 1991, Nixon et al. 1996). n >90% of these inputs occur from wastewater (Alber and Chan 1994).

3. 9 SYMPTOMS OF EUTROPHICATION n Elevated nutrient concentrations (Kelly 1998) and phytoplankton biomass (HydroQual 1994) n Almost total demise of seagrass beds, and heavy epiphytization of remaining beds (Colaruso, EPA) n Low dissolved oxygen concentrations in Inner Harbor (MWRA unpubl. data) n Supports benthic invertebrate communities typical of moderately degraded environments (Blake et al. 1998).

20. 9 CONCLUSIONS n Changes in water quality have been observed in Boston Harbor since transfer of Nut Island flows. n The South Harbor has shown decreased concentrations of DIN, increased water clarity, and variable responses of biomass of phytoplankton. n The North Harbor has shown increased DIN concentrations, a small increase in clarity at the outfalls, and no change in phytoplankton biomass. n The phytoplankton responses to increased nitrogen loadings appear to have been manifested in west Mass Bay.