Mosquito Lagoon
The 2026 health assessment for the Mosquito Lagoon is “Slight Improvement / Stable.” The 2025 assessment was “large improvement” due to seagrass gains. While seagrass coverage was stable in 2026, chlorophyll-a and turbidity levels declined within the basin. These declines influenced the water quality and algal bloom scores.
Algal Blooms
Chlorophyll-a data collected between August 1, 2025 to August 1, 2026 show the Mosquito Lagoon experienced algal bloom conditions 51.90% of the time. The median chlorophyll-a concentration in the basin for the year was 15.29 µg/L, earning a “fair” assessment. Mosquito Lagoon had the highest number of harmful blooms of any basin.
Salinity
Salinity levels in Mosquito Lagoon were higher between August 2025 and August 2026 than most other basins (median= 30.65 ppt). This is likely due to how long water stays in the basin and how isolated it is from freshwater input. These higher salinity levels are ideal for seagrass growth and likely contribute to the successful rebounding of seagrass meadows measured in the basin over the past two years.
Seagrass
The Mosquito Lagoon had a “slight increase” in seagrass coverage for the 2026 assessment. Based on St. Johns River Water Management District mapping data, coverage changed from 15,099 acres of seagrass in 2023 to 15,429 acres in 2025 for a 1.49% increase in coverage. Mapping data are taken every two years and 2027 coverage will be available in the spring of 2028.
Sediment Health
Sediment health data points for the Mosquito Lagoon came from MRC, Florida Institute of Technology, and Smithsonian Fort Pierce Marine Station research. Sediment quality studies are an area where we need to expand research efforts to inform Lagoon health and restoration projects. However, what sediment data that are available indicate good overall soil health, which is good news for seagrass potential.
Wastewater Spills
From August 2025 to August 2026, there were 12 wastewater spills that affected the Mosquito Lagoon watershed with two spills suspected of releasing into the Lagoon. Of those two spills, both released a total of approximately 54,000 gallons of untreated wastewater.
Water Quality
Overall water quality in the Mosquito Lagoon was “poor” in 2026. The health indicator assessment is based on averaging pH, turbidity, total nitrogen, total phosphorus, dissolved oxygen, and chlorophyll-a scores in the basin. The Mosquito Lagoon water quality is broken down below. The basin had an overall decline in health from “fair” in 2025. This is due to higher chlorophyll-a concentrations which negatively affected turbidity (water clarity).
Your Financial Support Makes It Happen!
Donate to become an Annual Member Today!
Marine Resources Council (MRC) coordinates Lagoon-wide efforts to Save the Indian River Lagoon, but we need your support to succeed. It will take a community to save the Lagoon, working at all levels.
MRC is holding government workshops, coordinating diverse stakeholder groups, showcasing community leaders, and working with businesses and individuals to encourage actions that will help save the Indian River Lagoon.
This website is managed by the Marine Resources Council, a 501(c)(3) nonprofit organization that has been dedicated to protecting and restoring the Indian River Lagoon since 1983.
Marine Resources Council • 3275 Dixie Hwy NE, Palm Bay, FL 32905.
Community Workshops
Science
LagoonWatch
2025 Report
2024 Report
IRL Action Assemblies
Restoration
Mangrove Nursery
Education
Lagoon at Noon
Low Impact Development
2026 LID Conference
2025 LID Conference
2024 LID Conference
2023 LID Conference
2022 LID Conference
2021 LID Conference
Teacher Resources
Rain Barrels
Site development by Editype.