Species that evolve in estuaries are therefore adapted to tremendous variability and extreme conditions in their environment. Long considered to be wastelands, estuaries have had their sediments dredged, marshes and tidal flats filled, water polluted, and shorelines reconstructed to accommodate housing, transportation, commerce, industry, and agricultural needs. As our population grows and the demands imposed on our natural resources increase, so too does the importance of protecting these resources for their natural and aesthetic values. Many marine organisms, and most commercially valuable fish species, depend on estuaries at some point during their development. Nutrients are essential to a healthy aquatic ecosystem, but in excess can lead to algal blooms causing eutrophication, a condition which results in low dissolved oxygen.
Water draining from uplands carries a load of sediments and nutrients.
As the water flows through salt marsh peat and the dense mesh of marsh grass blades, much of the sediment and nutrient load is filtered out. This filtration process creates cleaner and clearer water. Salt marsh dominated estuaries provide natural buffers between the land and the ocean. They protect upland organisms as well as billions of dollars of real estate that might otherwise be subjected to more intense natural forces. What's Being Done Recognizing human threats and the natural value of estuaries, Congress created the National Estuary Program in 1987 as part of the Clean Water Act.