They dug canals discharging fresh water into the lagoon, five times the historical volume.

Huge population influx resulted in sewage, and stormwater runoff from roadways, polluting the lagoon.

[7] The full length of the Indian River Lagoon is 156 miles (251 km), extending from Ponce de León Inlet in Volusia County, Florida, to Jupiter Inlet in Palm Beach County, Florida,[8][9] and includes Cape Canaveral.

[clarification needed] It serves as a spawning and nursery ground for different species of oceanic and lagoon fish and shellfish.

There was a mass death of manatees in 2021 due to the loss of seagrass, caused by leaks from septic systems and overuse of fertilizers.

[15][16] Red Drum, Spotted seatrout, Common snook, and the Tarpon are the main gamefish in the Titusville area of the lagoon system.

[14] Indian River Lagoon is abundant with bioluminescent dinoflagellates in the summer[18] and ctenophore (comb jellies) in the winter.

While this helps prevent life-threatening flooding in the Okeechobee area, it creates toxic blooms after entering the Lagoon, a threat to flora, fauna, and humans.

Some sports fish rebounded in population in the 1990s when gill nets were banned and pollution in the lagoon was reduced.

[20][21] The 1993–1996 data base used to track the movement of water through the St. Lucie Estuary and into Indian River Lagoon is described in Smith (2007).

This includes daily mean discharge rates for the 16 gauged canals emptying into the St. Lucie Estuary and Indian River Lagoon, predicted shelf tides, and wind speeds and directions recorded along the west side of the lagoon at about 27°32'N (corresponding to Segment 11 of the model).

[22] In 2007, concerns were raised about the future of the lagoon system, especially in the southern half where frequent freshwater discharges seriously threatened water quality, decreasing the salinity needed by many fish species, and have contributed to large algae blooms promoted by water saturated with plant fertilizers.

[citation needed] In the mid 1990s, the lagoon has been the subject of research on light penetration for photosynthesis in submerged aquatic vegetation.

3) Muck from construction, farming, erosion and dead plants find their way to the bottom of the lagoon, preventing growth and consuming vital oxygen essential to marine flora and fauna; 4) Invasive species, including the Asian green mussel, South American charru mussel, and the Australian spotted jellyfish, eat clams and fish larvae.

A brown tide bloom, caused by the algae species Aureoumbra lagunensis,[29] was blamed for the low oxygen levels.

The algae growth originated in the no-motor zone of the Merritt Island National Wildlife Refuge.

Pollution is worse in areas near no inlets, such as the Mosquito Lagoon, North IRL, and the Banana River.

[3] According to the Florida Oceanographic Society, nearly 1 million people live and work in the Indian River Lagoon region.