Experts say main stem of St. Johns River stable but tributaries show persistent pollution problems

Dr. Jerry Pinto, lead author of the 18th State of the River report and a researcher at Jacksonville University, told the Jacksonville Waterways Commission on Jan. 14 that while the main stem of the St. Johns River remains largely within acceptable ranges, many tributaries continue to exceed water‑quality thresholds for bacteria and nutrients.

"For the most part, the mainstream is okay," Pinto said, but he added that "the tributaries remain unsatisfactory and unchanged," listing Miller Creek, Pottsburg Creek, Red Bay, Silversmith and Cowhead Creek among the worst offenders. Pinto said the report uses enterococcus for marine sections and E. coli for freshwater as indicators of broader pathogen risk.

Pinto warned that data gaps limit confidence in trend analysis: "We have a massive reduction in the amount of data that's collected in 2024 compared to previous years," he said, noting that algae sampling in some areas dropped to single digits. Commissioners pressed for clarity on whether the drop in sampling reflected funding cuts or other operational changes.

The report highlights several drivers of degraded tributary conditions: an estimated more than 60,000 septic tanks in the watershed (about 24,000 were identified for connection or removal), recurring sanitary sewer overflows (181 events in the latest reporting year), and apparent increases in phosphorus tied in part to biosolids application from external sources. Pinto described biosolids land‑application sites and said data collected since 2020 suggest a phosphorus uptick in some locations.

Pinto also emphasized aquatic‑life concerns: "Blue crab is the biggest fishery in the St. Johns River," he said, and landings have begun to decline; he noted sea‑level rise is increasing salinity stress on submerged grass beds. He urged expanded, targeted monitoring in tributaries where algal blooms and contaminants are most likely to occur and encouraged community use of the report’s sightings app.

Commissioners and staff asked for a deeper review; Council Member Mike Barker and others urged follow‑up to determine why 2024 sampling declined and how to restore consistent monitoring. Pinto said agencies collect more samples in the main stem than in tributaries and that expanding tributary monitoring is costly but important for targeting remediation.

The commission did not take formal action on the report but requested staff follow up and made the full report and an executive‑summary brochure available via a QR code included in its packet.