During summer, the Copper River carries a million metric tons of sediment to the Pacific Ocean every day.  In fact, it is the largest source of sediment for the entire Pacific Ocean!  

This sediment creates a 700,000-acre network of tidal flats, sloughs, marshes, and estuaries that form the largest wetland on the Pacific coast of North America.  These wetlands are rich in tidal marine life, such as mollusks, clams, and fish, which makes them an important spot for migratory birds resting and refueling on their journey to Alaska.  Over 10 million birds migrate through the Copper River Delta every year.