A Deep Dive Into the East River

Overview 

The East River serves as a vital ecosystem and transportation route within New York City. Making its way past the Bronx, Manhattan, Queens and Brooklyn, it connects the Long Island Sound with Upper New York Bay. It has acted as a vital transportation route for centuries, and more recently, a site for waterfront recreational activities. The NYC ferry utilizes the river to transport passengers from South Brooklyn and the Rockaways all the way up to Throgs Neck, Bronx. Waterfront areas such as Brooklyn Bridge Park have also gained popularity in recent years, providing parks, bike paths, basketball courts and sports fields. 

An Estuary, Not a River 

Despite its name, the East River is not actually a river; it is a tidal estuary. An estuary is a coastal area in which fresh water from a river or stream mixes with salt water from the ocean. The water in an estuary is brackish, meaning there is a mix of salt and fresh water. The East River receives some freshwater from the Harlem River, and saltwater from the Long Island Sound and New York Harbor. However, the Harlem River itself is also not a true river; it is a tidal straight. It contains fresh water from the Hudson river, but also receives salt water from the East River. Essentially, the Harlem and East rivers exchange fresh and salt water, resulting in both being brackish, as opposed to just salt or fresh water. The flow of fresh water into the East River and salt water into the Harlem River depends completely on the tides. The change in tides results in the salt levels of both rivers fluctuating both often. The East River also has other freshwater tributaries such as the Flushing River, Newton Creek, Luyster Creek and Gowanus Creek. These rivers and creeks provide additional freshwater to the East River.