St. Johns River (Upper)

The St. Johns River (officially Saint Johns River, but commonly spelled St. John's River) is the longest river in the U.S. state of Florida, stretching 310 miles (500 km) from Indian River County to the Atlantic Ocean in Duval County. The St. Johns River is the second longest river in the United States that flows in a generally northwards direction. It was designated as one of the American Heritage Rivers in 1997.

The elevation change from headwaters to mouth is only about 30 feet, making the St. Johns one of the world's "laziest" rivers[1]. Its extremely low velocity, combined with the generally level elevation, causes the St. Johns to spread out to a great width for much of its course. During periods of low flow, the river can be influenced by tides as far south as Lake Monroe - 161 miles inland. For a distance of over twenty miles before arriving at downtown Jacksonville, the river's average width exceeds two miles, and in some places, exceeds three miles in width. The slow flow of the St. Johns makes it difficult for pollutants to be flushed from the waters, which has become a serious problem for the river ecosystem. Still, the river is home to numerous species of plants and animals. It is not uncommon to see dolphins in the river east of Jacksonville and manatees in the springtime when the water warms up. Alligators, bald eagles, ospreys, stingrays, and many species of fish—both salt and fresh water—are found living in the river and on its banks. The entire basin is managed by the St. Johns Water Management District.

The upper (southern) basin of the river has indistinct banks, with numerous sloughs and lagoons, often pooling into ponds and lakes. Some of the larger lakes are known today as Blue Cypress Lake, Lake Hellen Blazes, Sawgrass Lake, Lake Washington, Lake Winder, Lake Poinsett, Ruth Lake, Puzzle Lake, Lake Harney, Lake Jesup and Lake Monroe.

Below Lake Harney, the river is joined by the Econlockhatchee River, and runs between higher bluffs on either side, forming the middle basin. This part of the river runs through what is now the Ocala National Forest

The St. Johns is known for excellent fishing, especially largemouth bass. Its estuarial nature provides both freshwater and saltwater or brackish-water species. Saltwater species include redfish, flounder, tarpon, and the brackish water sea trout, known locally as the "gator trout". A recent report states that saltwater species have been venturing farther up the river (southwards) in recent years.

Some of the best known fishing occurs in January–March, when the American shad run up the river, and it becomes full of trolling boats. The shad, like the salmon, are anadromous and live most of their life at sea. They are caught primarily for the eggs, shad roe, for the flesh is below average and full of small bones.

As the St. Johns River flows through the city of Jacksonville, Florida it is spanned by seven bridges. The Jacksonville Port Authority (JAXPORT) facilities at the mouth of the St. Johns River make up Florida's second largest port. In fiscal year 2003, JAXPORT handled over 1,500 ships, delivering almost 700,000 containers and over 500,000 cars. Some of the major local commodities include gypsum and oil.

The U.S. Navy maintains the Naval Air Station Jacksonville and Naval Station Mayport near the river's mouth.

Starting at the river's mouth and moving upstream, major tributaries of the St. Johns River include Pablo Creek, the Trout River, the Arlington River, the Ortega River, Doctors Lake, Julington Creek, Black Creek, the Cross Florida Barge Canal, the Oklawaha River, the Wekiva River, Lake Jessup, and the Econlockhatchee River. Fort Drum Creek drains into the St. Johns Marsh, the source of the river.