Thermal imaging could help locate source of bacteria in Pages Creek

Pages Creek has seen worrying levels of enterococci bacteria since the testing began
Published: Oct. 1, 2021 at 3:46 PM EDT
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WILMINGTON, N.C. (WECT) - Water quality issues have been an ongoing concern in New Hanover County. Since 2008, the county has conducted water monitoring studies of seven tidal creeks in the county, tracking things like dissolved oxygen levels and elevated bacteria levels.

One creek in particular has seen worrying levels of enterococci bacteria since the testing began.

Pages Creek, which is in the Ogden area of New Hanover County, saw elevated levels of enterococci bacteria 13 times over the past year, and since testing started, has predominantly scored ‘poor’ when it comes to bacteria levels.

In response to the elevated levels of bacteria and the risk to human health it poses, the county funded multiple studies to test the DNA of the bacteria, both times finding human DNA, leading to questions of its source.

“After evaluating the long-term trend in Pages Creek, water quality monitoring has indicated elevated levels of enterococci bacteria exist in the upper and middle portions of the creek. Past investigations of the bacteria had concluded that the bacteria were from a human source and not from other animals in the area. In addition, an investigation of septic systems and sewer infrastructure came back inconclusive,” according to the report.

To discover the origin of the bacteria, the county partnered with UNCW and Coastal Protection Engineering to launch a drone equipped with thermal imaging sensors to try and track the source. In these images, temperature anomalies can be used to detect effluents — which is the outflowing of water into Pages Creek. The results of the thermal imaging flyovers along with ground surveys detected several possible locations that the bacteria could have come from.

“The county funded the study because previous efforts had not determined the source of contamination. The study was conducted earlier this year and showed some potential areas, but nothing conclusive has been determined, so we are continuing to work with CPE to determine the source,” according to a statement from New Hanover County.

There were several locations that showed some anomalies, but ultimately, the study revealed two likely sources

“Two targets, however, were identified to be on public property in proximity of the two sewage lift stations adjacent to the long-term monitoring sites at PC-BDUS and PCBDDS (Figures 4 and 10). Groundtruthing these sites revealed several subterranean seeps entering the creek from the streambank adjacent to each lift station (Figures 12 and 13). New Hanover County Planning staff has worked with CPE to perform additional water quality testing in two areas where the thermal imagery showed peculiar temperature differences. This testing has indicated Enterococci bacteria in water coming from the seeps mentioned above,” according to the report.

However, the initial testing is not conclusive.

“More samples and PCR tracing will be needed in order to make a definitive determination as to whether that groundwater contains bacteria and if the bacteria is from a human source,” according to the report.

The two sites of concern are the locations of CFPUA lift stations, sites that move wastewater from lower elevations to higher elevations.

When reached for a statement on Friday, CFPUA issued the following response.

“CFPUA is aware of this, and our staff have been working closely with their counterparts at New Hanover County to try to identify the cause. CFPUA staff has inspected nearby infrastructure, including lift stations, and have found no leaks or other vectors that might result in the bacteria levels being reported. We are continuing to work with the County on this situation. One next step that has been discussed is conducting tests to determine whether the bacteria originated from humans or some other source, which could help identify the cause.”

County commissioners will hear an update on the latest findings at their upcoming meeting on Oct. 4.

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