The work upon which this publication is based was supported in part by funds provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Research Act of 1964. These bodies of water are used as permanent homes or nursery grounds for many of the important forms of marine life.
Estuaries also provide protected transportation routes for cargo ships and barges.
Because of their biological productivity and their economically advantageous locations, estuaries often attract industrial and commercial development along with associated dense populations. Because of industrial and metropolitan development, estuaries are often expected to accept large amounts of waste materials. Many estuaries are large in size and give the appearance of being able to assimilate large volumes of this waste material. In actuality, estuaries may act as natural traps for pollutants. The fresh-water flow into some estuaries is relatively small.