Water Quality

The water quality of the East River is affected by both natural and man-made forces. The natural forces driving water quality include the mixing of sea water with fresh water from the Hudson River, and the seasonal fluctuations in temperature that affect plant growth and the presence of marine animals.

Human activity adversely affects the River water quality to a much greater degree than natural processes, through both historical and present behaviors. The Manhattan and Brooklyn shores of the East River have seen a great reduction in industrial activity since the mid-1900s, but industry still has an impact on water quality through sediment diffusion and residual contaminants in soils. Current activity affects the River, as well. The River is used as
a shipping route, and is at risk of petroleum or other chemical spills from vessels traversing its waters. Stormwater runoff also carries contaminants left on surfaces by automobiles, fertilization practices, aerial deposition, and general human consumption waste (trash).

Most important to human health is the discharge of CSOs into the River during storm events. When precipitation occurs, runoff is combined with untreated sewage within City sewers. In events over a certain threshold, the wastewater system becomes overburdened and excess is discharged directly into waterways, resulting in short-term spikes in fecal coliform (such as E. coli) concentrations which can cause a variety of infections in humans.

Currently, the NYCDEP classifies the East River as Use Classification I, indicating that it is suitable for secondary contact recreation, such as boating, and fishing.