Delivered at 2008 Boston Harbor Islands Science Symposium.
Water quality in Boston Harbor in 2007 was significantly improved relative to conditions prior to 2000, the year the secondary-treated discharges from the Deer Island wastewater treatment facility to Boston Harbor were diverted offshore. Since 2000, nitrogen concentrations and biomass of phytoplankton in the harbor water column have decreased by approximately 50%. Midsummer dissolved oxygen concentrations in the bottom-waters have increased, and counts of pathogen indicator bacteria have decreased. Water clarity has remained much the same, but the sea grasses that at the start of the century covered much of the harbor seafloor, are showing evidence of recolonization.
