The St. Lucie River is a estuary linked to a coastal river system in St. Lucie and Martin counties in the Florida, United States. The St. Lucie River and St. Lucie Estuary are an "ecological jewel" of the Treasure Coast, central to the health and well-being of the surrounding communities. The river is part of the larger Indian River Lagoon system, the most diverse estuarine environment in North America with more than 4,000 plant and animal species, including manatees, oysters, dolphins, sea turtles and seahorses. Historically, the St. Lucie was a freshwater river with no connection to either the Atlantic Ocean or Lake Okeechobee. In 1892, an inlet was dug by local residents to provide direct access to the Atlantic Ocean. During the 1900s, the river and its watershed underwent a series of modifications for navigation, flood control and water supply purposes, thus changing the St. Lucie from a river to an estuary. Location The North Fork of the St. Lucie River flows south from St Lucie County into Martin County where it joins the north-flowing South Fork, which was once called the Halpatiokee River, just south of the old Roosevelt Bridge (Old Dixie Highway) in Stuart to form the main St. Lucie River. It then passes under the Florida East Coast Railway drawbridge and the new high-level Roosevelt Bridge (U.S. Route 1) and flows east with Rio on the north side and Stuart on the south until it reaches the northern end of the Sewall's Point peninsula, where it runs south under the Evans Crary Bridge to the end of Sewall's Point, where it flows into the Indian River Lagoon directly west of the St. Lucie Inlet which goes into the Atlantic Ocean. The entire river is accessible to Lake Okeechobee by the Okeechobee Waterway. The main river passes through Sewall's Point, Port Salerno, Stuart, and Jensen Beach. The South Fork passes through Palm City. Although brackish for most of its length, the salt content of the South Fork diminishes considerably south of the Kanner Highway bridge. The headwaters of the South Fork are located in ranchland and scrub forest, primarily to the east of I-95 and northwest of Hobe Sound. The North Fork passes through Port Saint Lucie and White City. A Club Med resort lies on the eastern shore of the North Fork of the river at Greenridge Point. The North Fork is brackish along most of