Saint Johns River is a 355.2 mile stream, with the associated WBID(s): 2213B, 2213C, 2213D, 2213F, 2213I, 2893I, 2893Z.

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. It was designated as one of the American Heritage Rivers in 1997 and pegged by an environmental organization as the 6th Most Endangered River in America in 2008. The Saint Johns is north-flowing, which is somewhat unusual among U.S. rivers.