Healthy waterways are important for both aquatic life and humans who use the water for recreation.

We measure the quality of harbor water through two key indicators:

• Dissolved oxygen is essential for most aquatic life. Coastal habitats and ecosystems thrive in environments with high concentrations of dissolved oxygen.

• Concentrations of fecal coliform bacteria and Enterococci bacteria. Higher levels of these bacteria can mean there is sewage-related water pollution. Though most of these bacteria do not cause disease, higher concentrations can indicate the presence of pathogenic (disease-producing) bacteria.

How we monitor harbor water quality

Water quality standards are set by New York State and monitored by the NYC Department of Environmental Protection (DEP) annually through the Harbor Survey. The Harbor Survey Program has grown to include 40 sites throughout New York waters. Department of Environmental Protection scientists sample these sites weekly during the summer season (May - October) and monthly during the winter season (November - April).

New York’s harbor water quality today

Bacteria levels show that water meets minimum standards

Since the 1990s, average harbor-wide surface water fecal coliform levels have been well below the state maximum standard for fishing and boating (2,000 cells per 100mL, from 5+ samples) and bathing and other recreation (200 cells per 100 mL from 5+ samples).

Since the NYC DEP began monitoring enterococci in the early 2000s, levels have remained below the state maximum standards. Short-term spikes in bacteria may occur after heavy rain.

Dissolved oxygen levels show that water exceeds minimum standards

NYC DEP reports the open water summer average levels of dissolved oxygen harbor-wide, from surface and bottom water, every year. Levels above the state minimum standard (5.0 mg/L) indicate a harbor suitable to most aquatic life forms. Since the 1990s, the annual summer average for surface and bottom water dissolved oxygen levels of open water sites have been above New York State standards.

For more information on harbor quality, please visit the most recent report from the NYC DEP Harbor Survey Report. For information on current beach water quality, please visit DOHMH’s beach water quality map.