The Esopus Creek is a tributary of the Hudson River that drains the east central Catskill Mountains of the U.S. state of New York. From its source at Winnisook Lake on the slopes of Slide Mountain, the Catskills' highest peak, it flows across Ulster County to the Hudson at Saugerties. Many tributaries extend its watershed into neighboring Greene County and a small portion of Delaware County. Midway along its length, it is impounded at Olive Bridge to create Ashokan Reservoir, the first of several built in the Catskills as part of New York City's water supply system. Its own flow is supplemented 13 miles (21 km) above the reservoir by the Shandaken Tunnel, which carries water from the city's Schoharie Reservoir into the creek.
The Esopus's role in the state and regional economy has led to a concentrated effort to protect and manage it, particularly on the upper stretch. The interests of the various stakeholders have not always converged, particularly where it concerns the city's management of its water needs. Turbidity created by discharges from the Shandaken Tunnel after a 1996 flood led to a successful lawsuit against the city and a state regulation; downstream of the reservoir the city has been criticized for contributing to flooding problems by releasing too much water during heavy rainstorms. Boaters and anglers have also clashed, and invasive species are beginning to enter the upper creek as well.