Climatic sensitivity of an estuary to the nutrient pollution is highly affected by water residence time, which in turn is dependent upon the magnitude of freshwater inflows to the estuary. For example, the Hudson River/NYC Harbor Estuary has not suffered from toxic algal blooms as much as other estuaries even though it is the most heavily nutrient-loaded estuary in North America (Howarth et al., 2006). This insensitivity of the estuary to the high level of nutrient pollution is largely attributed to its short water residence time), flushing phytoplankton out before they fully grow into harmful algal blooms. Consideration of seasonal variation is highly relevant here, because the residence time of water in the lower Hudson estuary may increase significantly during the summer due to reduced freshwater discharge of the Hudson River. In addition, the light limitation from turbidity is likely to diminish during the summertime periods, facilitating phytoplankton production (Howarth et al., 2000, 2006, 2011).