Saint Johns River

St. Johns River
St. Johns River near Astor
Name origin: Spanish: San Juan del Puerto
Country	United States
State	Florida
Tributaries
- left	Mills Creek River, Econlockhatchee River, Wekiva River, Alexander Springs, Salt Springs Run, Ocklawaha River, Rice Creek/Simms Creek, Black Creek (Clay County), Ortega River, Trout River
- right	Murphy Creek/Dunn's Creek, Julington Creek, Pottsburg Creek, Intracoastal Waterway/Sisters Creek
Cities	Sanford, Deltona, DeLand, Palatka, Green Cove Springs, Orange Park, Jacksonville
Landmarks	Blue Cypress Lake, Lake Hell 'n Blazes, Sawgrass Lake, Lake Washington, Lake Winder, Lake Poinsett, Lake Harney, Lake Jesup, Lake Monroe, Lake Beresford, Lake Woodruff, Lake George, Doctors Lake
Source	St. Johns Marsh
- location	near Vero Beach, Indian River County, Florida
- elevation	30 ft (9 m)
- coordinates	27°57′18″N 80°47′3″W / 27.95500°N 80.78417°W / 27.95500; -80.78417
Mouth	Atlantic Ocean
- location	Jacksonville, Duval County, Florida
- elevation	0 ft (0 m)
- coordinates	30°24′05″N 81°24′3″W / 30.40139°N 81.40083°W / 30.40139; -81.40083Coordinates: 30°24′05″N 81°24′3″W / 30.40139°N 81.40083°W / 30.40139; -81.40083
Length	310 mi (500 km)
Basin	8,840 sq mi (22,900 km2)
Discharge	for Mayport, Florida
- average	15,000 cu ft/s (400 m3/s)
- max	150,000 cu ft/s (4,200 m3/s)
St. Johns River surrounding with corresponding watersheds designated by the St. Johns River Water Management District: 1. Upper basin, 2. Middle basin, 3. Lake George basin, 4. Lower basin, 5. Ocklawaha River basin

The St. Johns River (Spanish: Río de San Juan) is the longest river in the U.S. state of Florida and its most significant one 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 headwaters to mouth is less than 30 feet (9 m); like most Florida waterways, the St. Johns has a very low flow rate 0.3 mph (0.13 m/s) and is often described as "lazy". It is notable among some that the river's course flows north, a relatively rare characteristic. Numerous lakes are formed by the river or flow into it, but as a river its widest point is nearly 3 miles (5 km) across. The narrowest point is in the headwaters, an unnavigable marsh in Indian River County. The St. Johns drainage basin of 8,840 square miles (22,900 km²) includes some of Florida's major wetlands. 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.

A variety of people have lived on or near the St. Johns, including Paleo-indians, Archaic people, Timucua, Mocama, French and Spanish settlers, Seminoles, slaves and freemen, Florida crackers, land developers, tourists and retirees. It has been the subject of William Bartram's journals, Marjorie Kinnan Rawlings' books, and Harriet Beecher Stowe's letters home. Although Florida was the location of the first permanent European settlement in what would become the United States, it was the last U.S. territory on the east coast to be developed; it remained an undeveloped frontier into the 20th century. When attention was turned to the state, however, much of the land was rapidly overdeveloped in a national zeal for progress. The St. Johns, like many Florida rivers, was altered to make way for agricultural and residential centers. It suffered severe pollution and human interference that has diminished the natural order of life in and around the river. In all, 3.5 million people live within the various watersheds that feed into the St. Johns River. The St. Johns, named one of 14 American Heritage Rivers in 1998, was number 6 on a list of America's Ten Most Endangered Rivers in 2008. Restoration efforts are under way for the basins around the St. Johns as Florida continues to deal with population increases in the river's vicinity.