The Econlockhatchee River (Econ River for short) is an 87.7-kilometer-long (54.5 mi) north-flowing blackwater tributary of the St. Johns River, the longest river in the U.S. state of Florida. The Econ River flows through Osceola, Orange, and Seminole counties in Central Florida, just east of the Orlando Metropolitan Area (east of State Road 417). It is a designated Outstanding Florida Waters.The origin of the river's name is not known definitively. In 1839 the spelling was recorded as “Econ-like Hatchee”. It is theorized that this represents a Muscogee name meaning “earth-mound stream”, with “econ-like” coming from ēkvnv (/iːkaná/), ‘earth, land’, and ... Source: Wikipedia