Fixed-station water-quality monitoring at Cape Hatteras National Seashore: 2015–2016 data summary - Version 1.1

Hynds, Mark; Starkey, Eric

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 Cape Hatteras National Seashore (CAHA) as part the NPS Vital Signs Monitoring Program. The continuous-monitoring data station is located at a dock at the Ocracoke Village boat ramp. This station collects conductivity, dissolved oxygen, pH, salinity, temperature, 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. Southeast Coast Network staff follow methods that were adapted from the water-quality monitoring program established by the National Estuarine Research Reserve Program (Wenner and Geist 2001). The Cape Hatteras 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. Highlights from the 2015–2016 data record are summarized in this report. The site was down for maintenance issues from August 2015 to May 2016. This data summary contains data for January through July in 2015, and June through December in 2016. The limited data availability should be taken into consideration when reading this summary. • Chlorophyll a concentrations were good for seven samples and fair for two samples. Values ranged from 1.62 µg/L to 12.91 µg/L. • Water clarity was good for four visits and poor for one visit (March 2015). • Mean monthly dissolved oxygen concentrations were good throughout the period, ranging from a low of 5.68 mg/L in September 2016 to a high of 11.78 mg/L in March 2015. No daily average dissolved oxygen concentration fell below 6.6 mg/L. • Mean monthly pH values ranged from a low of 7.7 in April 2015 to a high of 8.7 in August 2016. The daily mean value ranged from 7.9 to 8.2. • Monthly mean turbidity values were highest during February 2015 at 18.2 NTUs. The lowest individual turbidity reading for any given month was 0.0 NTUs, and a maximum reading of 75.2 NTUs was recorded in October 2016. • Water temperatures in 2015–2016 ranged from a minimum monthly mean of 4.8 °C (40.6 °F) in February 2015 to a maximum monthly mean of 28.7 °C (83.7 °F) in July 2016. Individual temperatures ranged from a minimum of -1.1 °C (30.0 °F) in February 2015 to a maximum of 33.2 °C (91.8 °F) in June 2015.

Fixed-station water-quality monitoring at Cape Hatteras National Seashore: 2015–2016 data summary - Version 1.1

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