Nearshore Water Quality Study
The general perception that water quality near the Island of Captiva is becoming degraded prompted the Captiva Community Panel and SCCF Marine Lab to obtain funding from Lee Tourism Development Council to st
udy the issue. The Marine Lab first characterized the near shore water quality through periodic and rain-event monitoring on the gulf and estuary sides of the island. The characterization showed rain events triggered elevated human indicator bacteria concentrations and that Captiva sources seemed to be adding significant nitrogen loading to the near shore waters. A source tracking effort then targeted Captiva groundwater and runoff to better identify the sources of nitrogen and bacteria. The study found stormwater runoff from diffuse terrestrial sources introduced indicator bacteria into the estuary and Gulf around Captiva in concentrations high enough to cause periodic beach advisories. The study also found that areas of Captiva Island which relied upon septic systems had significantly elevated levels of nitrogen in the groundwater and that this groundwater likely contributed to surface water loadings. However, concentrations of indicator bacteria in groundwater near septic systems were not elevated, suggesting these bacteria did not survive the septic system/groundwater environment. The study suggested more complete removal of nitrogen by existing septic systems would be prudent in addressing water quality issues in that area as well as reducing stormwater runoff through re-vegetation and management efforts.
Captiva Water Quality Assessment Project Final ReportCaptiva Water Quality Assessment Project Year One: Summary and Findings