Newly released seagrass monitoring data from 2025 shows a major increase in seagrass coverage across the Indian River Lagoon, offering one of the strongest signs yet that portions of the troubled estuary are recovering after years of environmental decline.
The latest figures from the St. Johns River Water Management District show the lagoon contained 17,042 hectares of seagrass in 2025, compared to 9,924 hectares in 2023, an increase of more than 7,000 hectares, or roughly 13,000 football fields.
District officials said field monitoring also showed seagrass becoming denser across the lagoon. Mean transect length increased from 84 meters in 2023 to 124 meters in 2025, while average transect cover rose from 3.95% to 10.77%.
Dr. Lorae Simpson, a supervising environmental scientist with the district, said the lagoon has seen a sharp rebound in recent years, though recovery remains incomplete.
“We've seen a 72% increase compared to our 2023 data, which is absolutely fantastic, but we are still 47% behind that historical coverage of 2007-2009,” Simpson said.
The district’s monitoring combines aerial mapping with in-water transect surveys to track both the overall spread and density of seagrass throughout the estuary.
“Combining aerial mapping with field transect data gives us a more complete picture of seagrass condition across the lagoon,” Simpson said. “While increases in extent and cover are encouraging, sustained monitoring at multiple scales is critical to guide where and how we focus our management efforts.”
Simpson said the recent growth is likely tied in part to drier weather conditions across Florida, which reduced freshwater runoff into the lagoon.
But with temperatures rising and the rainy season beginning, scientists are now watching closely to see whether the recovery can withstand conditions that have historically fueled algae blooms.
“This is the prime recipe for algal blooms to take place,” she said. “And so, essentially just watching the rain as well as the temperature, but hoping that our restoration work that we had done previously and that our partners as well as us are continuing to work towards have helped.”
Between 2009 and 2021, widespread algae blooms devastated seagrass throughout the lagoon, clouding the water and blocking sunlight needed for growth. While recent trends have been positive, Simpson said recovery has not been evenly distributed across the estuary.
She pointed to the central portion of the lagoon as an area where gains have lagged behind other regions.
“The central IRL is still lagging behind in recovery. We actually saw a decline in seagrass coverage in that region over the last two years,” Simpson said. “We saw large increases in the northern IRL and the Banana River Lagoon, smaller increases in the south central and the central IRL, and then a small increase in the Mosquito Lagoon because it already had a significant amount of seagrass.”
The district said restoration projects aimed at improving water quality may also be contributing to the rebound. In the early 1900s, canals were built to divert water east into the lagoon to support agriculture and flood control, altering the system’s natural hydrology and increasing nutrient pollution.
To address those impacts, the district has completed four canal diversion projects, C-54, Fellsmere Main, C-1 and the Crane Creek/M-1 Flow Restoration Project, designed to redirect water back toward the St. Johns River after treatment and storage.
Simpson said those projects are helping restore more natural water flow patterns.
“So instead of water making its way to the Indian River Lagoon, which we had changed the hydrology of in the early 1900s, now we're sending it back to the St. Johns River, where it was historically headed in the first place,” she said.
District Executive Director Mike Register said the latest data reflects years of restoration work throughout the lagoon system.
“These results reflect meaningful progress and years of coordinated effort to improve water quality across the lagoon,” Register said. “While we’re encouraged by the trend, continued investment in restoration and science-based management will be critical to sustaining this momentum.”
Despite the encouraging data, Simpson said the lagoon remains highly vulnerable and will require continued long-term restoration and monitoring efforts before it can fully recover.
“There's so many different other interconnecting factors within that that we all need to be maintaining and working towards because it is such a highly dynamic system,” she said. “Success for the Indian River Lagoon would be to get back to our historical coverage from 2007-2009. So we have 47 percent to go and I'm very hopeful that we can get there.”
The district plans to continue monitoring seagrass conditions through biennial aerial mapping and annual transect surveys as the rainy season begins and algae growth conditions increase.