Central Indian River Lagoon

The 2025 health assessment for the Central Indian River Lagoon is “okay” with significant variability across the five health indicators. This is a notable improvement from 2024, when the Central IRL was the only basin with an overall “poor” assessment. This change was driven by improvements in harmful algae bloom concentrations and seagrass coverage. Chlorophyll-a concentrations decreased, meaning algae concentrations were “good” across the basin with few substantial, long-lasting blooms.

While seagrass coverage is still very limited, there was a slight increase compared to past years. However, water quality remains “poor” with high nutrient concentrations (nitrogen and phosphorus), poor water clarity (turbidity), and a large number of wastewater spills.

Algal Blooms

Chlorophyll-a data collected between August 1, 2024 to August 1, 2025 indicate the Central Indian River Lagoon experienced harmful algal bloom conditions 43% of the time. Of those harmful algal bloom conditions, 63.2% of blooms were considered low bloom, 17.3% of blooms were considered mid bloom, and 19.5% of blooms were considered high bloom. The median chlorophyll-a concentration in the basin for the year was 4.40 ug/L (the average concentration value was 9.10 ug/L), earning a “good” assessment.

Salinity

From August 2024 to August 2025, median salinity in the Central Indian River Lagoon was at levels that support peak growth of oysters, clams, and at least two species of seagrass. While this is promising for restoration work, seagrass restoration (specifically) will be difficult until water clarity (turbidity) improves.

Seagrass

The Central Indian River Lagoon had a “Slight Increase” in seagrass coverage. Based on St. Johns River Water Management District satellite data, seagrass coverage improved from 1081 acres in 2021 to 1237 acres present in 2023. This represents a 14.5% increase in coverage. Satellite data are taken every two years and 2025 coverage will be available by spring of 2026.

Sediment Health

Sediment health data in the Central Indian River Lagoon are from Florida Institute of Technology research. Although data are sparse, they show good sediment conditions. This is good news for the possibility of future seagrass growth. However, sediment health data are still too limited to draw basin-wide conclusions.

Wastewater Spills

From August 2024 to August 2025, there were 44 wastewater spills that affected the Central Indian River Lagoon watershed with eight releasing into the Lagoon. Of those eight spills (between 1000 and 3,190,000 gallons), all eight released untreated wastewater. Although the total number of spills was down from 2024, the Central IRL had the largest spill in the Lagoon region at 3,190,000 gallons; 2,000,000 gallons were recovered from this spill during remediation.

Water Quality

Water quality in the Central Indian River Lagoon was “poor” in 2025. The health indicator assessment is based on averaging the pH, turbidity, total nitrogen, total phosphorus, dissolved oxygen, and chlorophyll-a scores in the basin. The Central Indian River Lagoon received a “good” for pH and chlorophyll-a concentration, “okay” for dissolved oxygen, “poor” for turbidity and total phosphorus, and “very poor” for total nitrogen. 2025 water quality data are largely consistent with 2024, only showing an improvement in chlorophyll-a that was balanced by a decline in dissolved oxygen concentration.