Fixed-station water-quality monitoring at Fort Pulaski National Monument: 2012 data summary

Gregory, M.; Rinehart, Aaron; Wright, Wendy

doi:10.36967/2195213

In 2006 the National Park Service (NPS) Southeast Coast Network (SECN) Inventory and Monitoring Program began collecting water-quality data in the estuarine waters near Fort Pulaski National Monument (FOPU) as part the NPS Vital Signs monitoring program. The continuous monitoring data station is approximately 1.5 kilometers south of the Fort entrance at a dock on Lazaretto Creek just upstream of its confluence with the Savannah River. This station collects pH, dissolved oxygen, water temperature, salinity, specific conductance, turbidity and water level data every 30 minutes. Additional water-quality measurements are made by SECN staff and include monthly measurements of water-clarity conditions, nutrients, and chlorophyll a levels. Methods used are adapted from the water-quality monitoring program established by the National Estuarine Research Reserve Program. The Fort Pulaski National Monument fixed-station water-quality monitoring site is part of the SECN estuarine water-quality monitoring program, which routinely collects data in the vicinity of seven coastal parks located along the southeastern U.S. coast. Information collected by this monitoring program will be used to help managers make better-informed decisions by understanding trends and variability related to water-quality conditions in park waters. Summary data are presented in annual data reports published by the SECN. Findings for 2012 are as follows: Orthophosphate (DIP) levels were fair in August and November, while dissolved inorganic nitrogen levels were good in August and fair in November. Chlorophyll a levels rated as good in October and November and fair from June to September and in December. Dissolved oxygen concentrations measured during monthly sampling were good throughout the year. Dissolved oxygen readings made at the continuous recording station ranged from 2.63 mg/L in October to 9.57 mg/L in January. Mean monthly dissolved oxygen concentrations ranged from 5.1 mg/L in August to 8.9 mg/L in January. Mean daily dissolved oxygen levels commonly fell below 5 mg/L in the vicinity of this site between late July and October. Monthly water-clarity measurements were fair to good, with February, June and December reported as fair during 2012. Turbidity readings made at the continuous recording station ranged from near 0 NTUs in January to 701.7 NTUs in July. The highest monthly mean turbidity levels occurred in September (32.1 NTUs). Daily average turbidity levels were generally between 15 to 30 NTUs and rarely exceeded 40 NTUs. Mean monthly salinity values ranged from 25.1 ppt in March to 27.8 ppt during August. Individual salinity readings ranged from 17.3 parts per thousand (ppt) in June to 37.9 ppt in April. pH values ranged between 7.3 and 8.7 throughout the year with the most acidic conditions occurring episodically throughout the summer months. Mean monthly pH values fluctuated from 7.7 to 8.3 trending to lower levels during the late spring and early summer months. In 2012, roughly 10% of data were excluded from analysis because they were considered anomalous. Anomalous data during 2012 was most commonly associated with problems with dissolved oxygen and turbidity for a variety of reasons, primarily due to unknown sonde malfunctions or poor calibration data.

Fixed-station water-quality monitoring at Fort Pulaski National Monument: 2012 data summary

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