Bald Head Island Conservancy

Federal Grant Brings Continuous Water Quality Monitoring to Bald Head Island 

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by Beth Darrow, Chief Scientist

In July 2022, the Conservancy installed a new high-powered water quality sonde at the mouth of Bald Head Creek as part of a 3-year US Coastal Research Program grant. Chief Scientist Beth Darrow is a principal investigator on this project led by Natalie Nelson from the Biological & Agricultural Engineering Department at NC State University. The project will pair high-frequency water quality data taken every 15 minutes from the YSI EXO2 instrument with traditional microbiological sampling to create a machine-learning model that will help predict whether water is safe for shellfishing. We are excited to own this sophisticated instrument to increase our understanding of our island’s water quality and its links to the Cape Fear River, which was also part of the Conservancy’s 5-year Strategic Plan. 

The sonde is collecting data on temperature, conductivity (salinity), dissolved oxygen, turbidity, total algae (chlorophyll), pH, fluorescent dissolved organic matter (fDOM), and tryptophan. The first six parameters are relatively standard and used throughout many monitoring programs throughout the United States. The fDOM and tryptophan sensors are new sensor types that we are testing to help predict fecal indicator bacteria/wastewater inputs. This technology has been used in fresh water, but has not yet been tested in brackish water. The computer model developed by Nelson and her student, pairing sensor measurements and microbiological data, could lead to a real-time sensor for wastewater inputs. This technology is also being tested in Morehead City in an area that has larger issues with fecal pollution than BHI, and it’s likely that the BHI site will be the more “pristine” comparison. It is exciting to be a part of such important research that could impact management of shellfish growing areas nationwide.

Conservancy staff and interns assisted NCSU PhD student Julia Harrison in July for the project’s first high-frequency sampling event, where microbiological samples were taken every two hours for 48 hours. Julia is now pairing the sample data with downloaded instrument data and analyzing it for trends. Conservancy staff are maintaining the instrument during its long-term deployment. We plan to conduct a series of high-frequency sampling events over the next two years, during dry periods and storms. 

The water quality sonde data will be made available to the public after it is downloaded and quality-checked. Eventually we hope to add telemetry capabilities so that data can be made instantaneously available via a web platform. This instrument will greatly enhance the Village of BHI Creek Water Quality data set, in which the Conservancy has taken weekly samples since 2012 and quarterly 24-hour samples since 2017. Through this monitoring data, we have observed long-term improvements in water quality on BHI over the past 5 years. 

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NCSU PhD student Julia Harrison conducts microbiological sampling during the project’s first high-frequency data collection in July



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