The upper course of the river is called the Econlockhatchee River Swamp. Located southeast of
Orlando, the swamp is long, from
Lake Conlin to
State Road 528. South of
State Road 532, the swamp is known as Cat Island Swamp, named after an island near
County Road 500A. The river is at its widest (1.6 km) here, bordered by
Lake Preston to the west. Seven miles downstream, the river's elevation is . The Disston Canal joins
Lake Mary Jane and
Lake Hart to the swamp. Turkey Creek Bay is an arm of the
swamp, through which the tributary
Turkey Creek flows. North of
Wewahootee Road, the Econlockhatchee River leaves the swamp and remains a free-flowing river for the rest of its journey to the
St. Johns River. == List of crossings ==