Anthropogenic impacts along Florida’s longest river

The St. Johns River is Florida’s longest at 500 kilometers, with an elevation change of less than nine meters. The low slope and long distance create incredible variability in water quality and flow between the fresh headwaters to the south in agricultural Central Florida and the estuarine waters of Jacksonville in Northeast Florida, a metropolitan area of 1,000,000 people. Despite the river’s designation as both a “class III” water body and a “National Heritage River,” intentional acts and unintended impacts are creating economically and ecologically costly repercussions. This valuable aquatic system is impacted by pollutants that enter the watershed upstream when the tide is ebbing and then from downstream when the tide is flooding. Recurring harmful algal blooms extending north from the upper St. Johns River and water-quality time series data collected from the lower St. Johns River highlight the anthropogenic impacts and the need for change.

Speaker: Melinda Simmons, Jacksonville University