Assessment of Estuarine Water and Sediment Quality at Timucuan Ecological and Historic Preserve: 2018 data summary

Starkey, Eric; Wright, Wendy; Cooper, Christopher

doi:10.36967/2266891

In July 2018 the Southeast Coast Network conducted an assessment of water quality at Timucuan Ecological and Historic Preserve 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 2010). 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 obtained when possible. All measured parameters were rated as good, fair, or poor based on thresholds set by the EPA (2012). Water clarity was rated fair at sixteen sites (52%), poor at fourteen sites (45%), and could not be sampled at one site (3%). Chlorophyll a concentration was rated good at ten sites (32%), fair at fourteen sites (45%), and poor at seven sites (23%). Dissolved inorganic nitrogen (DIN) concentration was good at twenty-six sites (84%), and fair at the remaining five sites (16%). Dissolved inorganic phosphorus (DIP) concentration was good at one site (3%), fair at twenty-nine sites (94%), and poor at one site (3%). Dissolved oxygen concentration was rated good at seventeen sites (55%) and fair at fourteen (45%). A water-quality condition summary index was calculated for each site sampled in Timucuan Ecological and Historic Preserve based on the categorical assessments of chlorophyll a, DIN and DIP concentrations, dissolved oxygen, and water clarity. This summary index indicated fair water-quality conditions at twenty-four sites (77%) and poor water-quality conditions at seven sites (23%). Based on the summary water-quality index rating, overall water-quality conditions at Timucuan Ecological and Historic Preserve during sampling in 2018 were poor. This rating is due to more than 20% of sites being ranked as having poor water-quality conditions resulting from low water clarity and elevated chlorophyll a. For sediment, ecological condition was ranked as good at thirty-one sites (100%). As a result, no adverse impacts to benthic organisms due to sediment contamination are anticipated at any of the sampled sites. This ranking was assigned according to the 2010 Environmental Protection Agency, National Coastal Condition Assessment (NCCA) thresholds for sediment chemistry.

Assessment of Estuarine Water and Sediment Quality at Timucuan Ecological and Historic Preserve: 2018 data summary

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