St. Johns River

The St. Johns River (Spanish: Río San Juan) is the longest river in the U.S. state of Florida and its most significant for commercial and recreational use. At 310 miles (500 km) long, it winds through or borders twelve counties, three of which are the state's largest. The drop in elevation from the headwaters to the mouth is less than 30 feet (9 m). Like most Florida waterways, the St. Johns has a very slow flow rate at 0.3 mph (0.13 m/s), and is often described as "lazy". Numerous lakes are formed by the river or flow into it, but as a river its widest point is 3 miles (5 km) across, spanning several miles between Palatka and Jacksonville, the latter being the largest urban area on the river. The narrowest point is in the headwaters, an unnavigable marsh in Indian River County. In all, 3.5 million people live within the various watersheds that feed into the St. Johns River. With a drainage basin of 8,840 square miles (22,900 km2), the St. Johns is one of the major interior wetlands of Florida. It is separated into three major basins and two associated watersheds for Lake George and the Ocklawaha River, all managed by the St. Johns River Water Management District. Like all waterways in Florida, the St. Johns is fed primarily by rainfall, most of which is immediately deposited into the river and its tributaries as stormwater runoff. Much of the water flowing into the St. Johns also comes from the Floridan Aquifer, a natural underground reservoir that serves as the fresh water source for populations living north of St. Petersburg. The banks of the St. Johns have been populated by Archaic people, Timucua, Mocama, French, Spanish, and British settlers, Seminoles, slaves and freemen, Florida crackers, land developers, tourists, and...