Indian River Lagoon

The Indian River isn’t a river! It's a lagoon (also known as an estuary), which is a coastal body of water that is separated from the ocean by barrier islands. Natural or man-made inlets that cut through the barrier islands allow saltwater to mix with freshwater that comes from rainfall and runoff from the surrounding land. Since there are relatively few ocean inlets within the Indian River Lagoon (IRL), the exchange of water with the open ocean is limited. The limited mixing of waters is because of the lagoon’s location, shape, shallowness, and variations in quantities of freshwater that flows into the system. This complex relationship influences the amount of mixing and circulation of waters within the lagoon and, thus, the habitats that are formed.

 The various habitats that are formed by the mixing of saltwater and freshwater are home to more than 2,200 animal species and 2,100 types of plants. Because the habitats in the IRL are diverse, specialized, and unique, they have a low tolerance to change. Due to human activities, changes to the IRL have already begun. This situation was recognized when IRL was designated as “a priority water body in need of restoration and special protection” in the 1987 Surface Water Improvement and Management (SWIM) Act and in 1991 when IRL became part of the National Estuary Program (NEP). This program promotes “the protection and improvement of water quality and the enhancement of living resources within an estuary.”

Aerial view of Sebastian inlet
Seagrass shoals of the Sebastian Inlet <>