Assessment of estuarine water quality at Fort Frederica National Monument, 2008

Gregory, M; DeVivo, Joe; Flournoy, Phillip; Smith, Katy

In August 2008, the Southeast Coast Network, in cooperation with the University of Georgia Marine Extension Service, conducted a water-quality assessment at 30 randomly selected sites at Fort Frederica National Monument as a part of the National Park Service Vital Signs Monitoring Program. Monitoring was conducted following methods developed by the U.S. Environmental Protection Agency as a part of the National Coastal Assessment Program and included laboratory analysis for chlorophyll a, total dissolved nitrogen and phosphorous concentrations, and field measurements of water temperature, pH, dissolved oxygen, and salinity. Estimates of water clarity were made using secchi depth measurements and were adjusted for naturally occurring regional conditions. A water-quality condition summary index was calculated using the categorical assessments of water clarity, chlorophyll a, and total dissolved nitrogen and phosphorous concentrations. This index indicated overall poor water-quality conditions at Fort Frederica with more than 20% of the sites having two or more of the five water quality parameters rated as poor. High nutrient levels and decreased water clarity were the reason for the majority of poor water-quality condition ratings with elevated phosphorus levels measured at 29 of the 30 sites. Elevated nitrogen and phosphorus levels were measured at nine of the 30 sites. Many of the sites with elevated nutrient levels also exhibited lower water-clarity conditions. No discernable spatial patterns were noted among individual water-quality parameters although the generally high levels of nutrients, especially phosphorus, found throughout the park may warrant further investigations as to potential sources and/ or natural occurring background levels of nutrients.

Assessment of estuarine water quality at Fort Frederica National Monument, 2008

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