St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District
St. Johns River Water Management District -
Water bodies, watersheds and storm water

The Indian River Lagoon:
An estuary of national significance

The Indian River Lagoon is a diverse, shallow-water estuary stretching across 40 percent of Florida’s east coast. Spanning 156 miles from Ponce de Leon Inlet in Volusia County to the southern boundary of Martin County, the lagoon is an import­ant commercial and recreational fishery and economic resource. The total estimated annual economic value of the lagoon is $3.7 billion, supporting 15,000 full and part-time jobs and providing recreational opportunities for 11 million people per year.

The people attracted to the lagoon by its features — its vast diversity of marine life, plants and animals; temperate climates; accessibility and direct links to the Atlantic Ocean — have changed those characteristics over the last century and particularly within the last 50 years. Throughout recorded history, there have been fish kills, algal blooms and changes in water quality. The lagoon has had a natural ability to absorb a certain amount of pollutants. However, when overloaded, the lagoon suffers.

After years of declining water quality, the lagoon’s condition improved beginning in the early 1990s in conjunction with numerous restoration and water quality improvement projects and programs. Seagrass coverage in the estuary — used by scientists as an indicator to determine relative water quality — climbed steadily from 1993 through 2011. The projects and programs during that timeframe included:

  • Cost-share stormwater projects that capture sediments before they reach the lagoon
  • Regional projects that include dredging muck from major lagoon tributaries
  • Coastal wetland restoration projects
  • Water quality and sediment studies by several state agencies and educational institutions
  • Seagrass mapping and monitoring by the St. Johns River Water Management District
  • Water quality monitoring by the St. Johns River Water Management District
  • Monitoring of fish populations by the Florida Fish and Wildlife Research Institute
  • The St. Johns River and South Florida water management districts sponsor of the Indian River Lagoon National Estuary Program (IRLNEP), which works with a network of partners and has implemented more than $80 million in projects to improve water quality in the lagoon. This investment has been leveraged with federal, state and local funding resulting in $200 million in capital improvements and preservation dollars for the lagoon.

Following the progress and improvements, an algal “superbloom” appeared in the portion of the system known as Banana River Lagoon in spring 2011. It ultimately spread into the northern Indian River Lagoon and farther north into the Mosquito Lagoon (see map). Concurrently, a lesser bloom extended from just north of Melbourne south to the Vero Beach-Fort Pierce area (see map). Approximately 47,000 acres of seagrasses were lost, a reduction of about 60 percent of the lagoon’s total seagrass coverage.

In August 2012, a brown tide bloom began in the Mosquito Lagoon and moved into the northern Indian River Lagoon near Titusville. The bloom reappeared in 2013. Compounding concerns are the losses of manatees and pelicans since July 2012 and bottlenose dolphins since Jan. 1, 2013. Various agencies are investigating the deaths.

Why did the superbloom occur? Many factors were in play, elements that may have contributed to a “perfect storm” of sorts. Preceding the blooms, long-term droughts had increased salinities in the lagoon and extremely low water temperatures occurred during the winters of 2010 and 2011. These extreme climatic events in conjunction with chronic, decades-long nutrient enrichment may have favored certain algae species that had previously never reached bloom proportions. While no single factor explains the superbloom, it is likely that these and other events contributed.

The St. Johns District, IRLNEP, federal and state agencies, local governments and educational institutions are individually and collectively working to find answers to the cause of the superbloom and to identify what, if anything, can be done in the future to limit or avoid a similar event. The various partners are investigating the possible causes of the blooms and developing strategies to reduce their magnitude, duration and frequency. Chief among this work are the Indian River Lagoon 2011 Consortium and the St. Johns District’s Indian River Lagoon Protection Initiative. The Initiative is focused on better understanding the sources, cycling and transport of lagoon nutrients and the long-term impacts from the loss of the lagoon’s seagrasses, as well as potential strategies aimed at restoring the lagoon to a seagrass-dominated ecosystem.


Ed Garland at (321) 676−6612 or


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St. Johns River Water Management District
4049 Reid Street, Palatka, FL 32177
(800) 725-5922