Fixed-station water-quality monitoring at Cape Hatteras National Seashore: 2012 data summary

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

doi:10.36967/2195212

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 pH, dissolved oxygen, temperature, salinity, conductivity, 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 Cape Hatteras National Seashore fixed-station water-quality monitoring site is part of the SECN estuarine water and sediment quality monitoring efforts, 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. This report presents data from the 2012 sampling year at Cape Hatteras National Seashore. Monthly water-quality data collected at the Southeast Coast Network site near Cape Hatteras National Seashore during 2012 reflect good to fair conditions throughout the year, with water-clarity rating good in the spring and early summer and fair in the late summer. Dissolved inorganic nitrogen and phosphorus indicated good conditions when available. Chlorophyll a levels rated fair during the late summer months, and good in June and October. Data were not available for the first five months, and last two months of the year. Mean monthly dissolved oxygen levels were good throughout the entire year, ranging from a high of 9.6 mg/L in February to a low of 6.4 mg/L in July and August. No daily average dissolved oxygen levels dipped below 5 mg/L. Mean monthly pH values ranged from a low of 7.9 in January to a high of 8.3 in June with very little variability throughout the year. Monthly mean turbidity values were highest during April at 18.9 NTUs. The lowest individual turbidity reading for any given month was ≤ 2.2 NTUs and a maximum reading of 175.4 NTUs was recorded in September. Water temperatures in 2012 were similar to those in 2011. The monthly mean high in July was 28.5 ºC (83.3 ºF) and 28.1 ºC (82.3 ºF) for 2012 and 2011, respectively. The lowest monthly average for both years occurred in January with 2012 readings approximately 5 ºC (9 ºF) degrees higher.

Fixed-station water-quality monitoring at Cape Hatteras National Seashore: 2012 data summary

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