Assessment of Estuarine Water Quality at Cumberland Island National Seashore: 2022 Data Summary

In July 2022, the Southeast Coast Network assessed water-quality at Cumberland Island National Seashore as part of the National Park Service Vital Signs Monitoring Program. Monitoring was conducted following methods developed by the Environmental Protection Agency (EPA) as part of the National Coastal Assessment Program (EPA 2014). Laboratory analysis measured chlorophyll a and total and dissolved concentrations of nitrogen and phosphorous. Field measurements included water temperature, pH, dissolved oxygen, and salinity. Water clarity, which requires a Secchi depth measurement, was calculated when possible. All measured parameters were rated as good, fair, or poor based on thresholds set by the EPA (2012). • Water clarity was rated good at all thirty sites (100%). • Chlorophyll a concentrations were rated fair at all thirty sites (100%). • Dissolved inorganic nitrogen concentrations were good at all thirty sites (100%). • Dissolved inorganic phosphorus concentrations were good at three sites (10%) and fair at twenty-seven sites (90%). • Dissolved oxygen concentrations (bottom) were rated good at twenty-four sites (80%) and fair at six sites (20%). • A water-quality condition summary index was calculated for each site sampled at Cumberland Island National Seashore based on the categorical assessments of chlorophyll a, DIN and DIP concentrations, dissolved oxygen, and water clarity. This summary index indicated good water-quality conditions at three sites (10%) and fair water quality conditions at twenty-seven sites (90%). • See supplemental materials to compare the distribution of good, fair, and poor ratings for each parameter across the period of record. • Based on the EPA summary water-quality index rating, overall water-quality conditions at Cumberland Island National Seashore during 2022 sampling were fair. • The EPA summary water-quality index rating is consistent with findings 2007–2017.

Assessment of Estuarine Water Quality at Cumberland Island National Seashore: 2022 Data Summary

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