Estuaries are areas partially surrounded by land where rivers meet the sea. They are characterized by varying degrees of salinity and complex water movements affected by ocean tides and river currents. Estuaries are living places hosting more wildlife births than any other ecosystem in the world, with a wide range of habitats for many different species of plants and animals. These nurseries are not only vital to animal populations, but also to the human population that relies upon them for drinking water, industry, food production and recreation. Estuaries are lined with vital wetlands that strain stormwater runoff from the land, absorbing a great deal of pollution from the water before it meets with rivers and bays.

A watershed is an area of land drained by a river or other body of water. The water that flows over the land's surface, usually from rain and snow, is called runoff. There are small watersheds, which receive runoff from a few acres into a creek, and large watersheds, which drain larger areas of land into a river. A large watershed is made up of many smaller watersheds, just as many small tributaries feed a large river. The Delaware River is fed by 216 tributaries and drains 13,539 square miles, including parts of New York, Pennsylvania, New Jersey and Delaware. Millions of people live within this large watershed, all of whom have an impact upon water quality each and every day.

The Delaware Estuary stretches from Trenton, New Jersey, and Morrisville, Pennsylvania, south to Cape May, New Jersey, and Cape Henlopen, Delaware, including all of the Delaware Bay and the tidal reaches of the Delaware River. A majority of the Estuary’s five million people live in one of the regions three largest cities, including Philadelphia, Camden, New Jersey, and Wilmington, Delaware. This highly commercialized area hosts the largest freshwater port in the world, accommodates the second-largest petrochemical port, and is home to five of the largest East Coast refineries, with over 42 million gallons of crude being transported on the Delaware River every day.

However, the Estuary is also a vital ecosystem, creating habitat for more than 130 species of finfish, as well as clams, oysters and crabs. The second largest concentration of migrating shorebirds in the Western Hemisphere is found in the Estuary, along with habitat for 15 different species of waterfowl, which total more than half-a-million individuals who either migrate through or spend the winter here. Also found in the Delaware Estuary is the largest population of spawning horseshoe crabs in the world. For additional insight into the living resources of the Estuary, please click here.

The Delaware Estuary faces many environmental challenges. Thus, it is vitally important for ecology and industry to continually work together to protect the Delaware Estuary: a precious resource that means so much to so many.

• Please click here to view an informative fact sheet in our "Delaware Estuary Information Gateway" section