New York City's Combined Sewer Overflow (CSO) Program

The City of New York is located within the center of a major estuary; the New York/New Jersey Harbor Estuary. The Harbor Estuary has a surface area of 300 square miles and a drainage area of over 16,000 square miles. This estuary supports a wide range of habitat and is a valuable economic asset that generates billions of dollars annually from numerous uses and activities including commercial and recreational fishing, boating and swimming.New York City's Department of Environmental Protection (NYCDEP) recognizes that combined sewer overflows (CSOs) can have an impact on the water quality of the New York Harbor and is advancing a 1.8 billion Citywide CSO Program to address CSO discharges from the over 450 CSO locations within the City. New York City is primarily served by a combined sewer system. Approximately 70% or 120,000 acres of the City have combined sewers. This equates to 4800 miles of combined sewers serving over 7 million residents within the five boroughs of NYC.NYC's Citywide CSO Program consists of eight individual project areas that together encompass the entire harbor area as shown on Figure 1. There are four open water projects (East River, Jamaica Bay, Inner Harbor and Outer Harbor), and four tributary projects (Flushing Bay, Paerdegat Basin, Newtown Creek, and Jamaica Tributaries).This paper will describe the CSO facilities NYC is building and planning under this major capital planning and construction effort as well as discuss some of the challenges faced by the City in implementing the program.