Fixed-station water-quality monitoring at Cumberland Island National Seashore: 2017–2019 data summary

Starkey, Eric; McCay, Dainiel

In 2005 the National Park Service (NPS) Southeast Coast Network (SECN) Inventory and Monitoring Program began collecting water-quality data in the estuarine waters near Cumberland Island National Seashore (CUIS) as part of the NPS Vital Signs monitoring program. The current continuous-monitoring station is located on the Sea Camp dock. This station collects pH, dissolved oxygen, temperature, salinity, conductivity, turbidity, and water level data every 30 minutes. Southeast Coast Network staff make additional water-quality measurements, which include monthly measurements of water-clarity conditions, nutrient concentrations, and chlorophyll a levels. Network staff follow methods adapted from the water-quality monitoring program established by the National Estuarine Research Reserve Program (Wenner and Geist 2001). Data and results are compared to EPA criteria (EPA 2012) which rate conditions as good, fair, or poor. The Cumberland Island National Seashore fixed-station water-quality monitoring site is part of the SECN estuarine water- and sediment-quality monitoring effort, which routinely collects data in the vicinity of seven coastal park units located along the southeastern U.S. coast (DeVivo et al. 2008; Gregory et al. 2013). 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. This data summary report contains data for January 2017 through December in 2019. A gap in data collection occurred between July 2018 and February 2019. Results in this report can be compared with those presented in the 2015–2016 fixed station water-quality data summary report (Hynds et. al. 2018). Key findings from the 2017–2019 data record are are listed below and summarized in this report. Chlorophyll a concentrations were good for eight samples and fair for sixteen samples. Values ranged from 2.19 µg/L to 14.80 µg/L. Water clarity was good for seventeen samples, fair for three samples, and poor for four sample. Mean monthly dissolved oxygen concentrations were good to fair throughout the period, ranging from a low of 1.6 mg/L in September 2017 to a high of 10.5 mg/L in January 2018. Nearly 70% of daily means were above the threshold for good (> 5.0 mg/l). Mean monthly pH values ranged from a low of 7.4 in September 2017 to a high of 8.0 in January 2018. The daily mean value ranged from 7.2 to 8.0. Monthly mean turbidity was highest during December 2017 at 96.5 NTUs (nephelometric turbidity unit). The lowest mean daily turbidity reading was 6.8 FNU (formazin nephelometric unit) in November 2019, and the highest mean daily turbidity of 335.9 NTUs was recorded in December 2017. Note that NTU and FNU are roughly equivalent measures. Water temperatures in 2017–2019 ranged from a minimum monthly mean of 10.9°C (51.6°F) in January 2018 to a maximum monthly mean of 30.0°C (86.0°F) in July 2018. Individual temperatures ranged from a minimum of 7.7°C (45.9°F) in January 2018 to a maximum of 32.6°C (90.7°F) in July 2018.

Fixed-station water-quality monitoring at Cumberland Island National Seashore: 2017–2019 data summary

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