The Department of Environmental Protection (DEP) last week announced it will be taking steps to assess an issue that has long been linked to poor water quality in New York Harbor.

DEP Commissioner Carter Strickland announced the agency will install remote sensors that monitor combined sewer overflows in real time at five combined sewer overflow outfall locations.

During heavy storms, the New York City sewer system often reaches capacity and must discharge a mix of stormwater and wastewater—called a combined sewer overflow (CSO)—into the city’s surrounding waterways.

These discharges are released from the city’s 423 combined sewer overflow outfalls.

“All of the new waterfront developments and recreational opportunities on New York City’s waterways show that New York Harbor has made a stunning comeback,” said Commissioner Strickland. “But there is always more work to be done, especially tackling the 100-year-old challenge of combined sewer overflows.”

The purpose of the pilot is to allow DEP to better evaluate the impact of combined sewer overflows on harbor water quality, respond to developing emergencies, enhance the existing public notification system for overflow discharges during rain storms, and optimize the existing sewer system.

Once installed, the monitors will be tested to determine how accurately they measure the volume of combined sewer overflow released at that outfall, and whether they can reliably transmit that data instantaneously.

The new types of real-time sensors should provide additional data that is not currently possible with the current combined sewer overflow monitoring system.

Right now, the city has 108 sensors at combined sewer outfall locations, located near recreational areas. These sensors have the ability to monitor and transmit the elevation of wastewater in the underground sewer system near combined sewer overflow locations.

However, the sensors do not detect the direction of flow, making it impossible to distinguish CSOs from any tidal effects. Moreover, the rate of flow is not measured, making it extremely difficult to quantify exactly how much combined sewer overflow is occurring at any given time.

The five outfall sites already selected for the pilot are at the following locations:

• Near the Navy Yard, which empties into the East River;

• In Dutch Kills, which ultimately feeds into Newtown Creek;

• At the Gowanus Canal;

• Near Soundview Park, which empties into the Bronx River; and

• Near Gravesend Bay

DEP is also planning to add three additional monitoring sites in the near future at outfalls leading into the Hudson River, the upper East River and Jamaica Bay.

DEP has also created a Waterbody Advisory webpage, available at www.nyc.gov/dep, showing real-time advisories for secondary contact—such as boating—for 25 waterbodies, that is being continuously improved.