Mercury testing expands at Lake Glenville
After testing last year found Lake Glenville’s walleye fish to have some of the highest mercury concentrations in North Carolina, state officials returned to Jackson County to look at mercury levels in other fish species.
“We asked them to come back and do some further testing on Lake Glenville and see how widespread it is,” said Paula Carden, Health Department director for Jackson County.
There’s already a statewide advisory on largemouth bass, but state workers returned, nets in hand, this October to sample other predatory fish species, such as smallmouth and spotted bass. It’s possible they could have snagged some other species for testing, perhaps trout and catfish, but Carden hasn’t gotten those results yet.
It was just about a year ago that the N.C. Department of Environment and Natural Resources — now known as the Department of Environmental Quality — first issued an advisory for Lake Glenville, finding that all but one of the 22 walleye fish tested had mercury levels above the state’s 0.4 milligram per kilogram action level.
Though the levels were high compared to those found in other area lakes, the resulting mercury advisory wasn’t exactly a surprise. Mercury has become a pretty common issue in lake environments, especially in predatory fish. Low levels of the metal occur naturally in the environment, but the more dangerous concentrations are mainly a result of fumes from fossil fuel burning. Those fumes rise into the atmosphere and can travel significant distances before condensing with water droplets and falling as rain. The rain eventually winds up in bodies of water, where bacteria convert the mercury into a form consumed by fish. The metal finds its way into the food sources for small fish, and bigger fish eat the small fish, concentrations of the metal accumulating in their bodies.
“It’s not the big shock or alert that it used to be to people, but we certainly want to make the public aware of it and request the proper testing,” Carden said.
Fontana Lake, Nantahala Lake and Santeelah Lake are all under mercury advisories as well. But testing at those lakes has covered multiple fish species, whereas walleye had been the only fish tested at Lake Glenville. The Jackson County Health Advisory Board wanted to know if anglers should think twice about eating more fish species than just walleye. They also questioned whether the issue might extend to other lakes in Jackson County, such as Bear Lake and Wolf Lake, and if stocked fish from hatcheries might contain mercury as well, Carden said.
The DEQ hasn’t granted the request for testing at other lakes and hatcheries as of yet. However, the county expects to get results from the second round of testing the state conducted in October sometime around early spring.
“We have asked them to hurry if possible,” Carden said.
Fishing is a popular sport in Jackson County, so it’s important to have as complete a picture as possible as to what is and is not safe to eat, Carden said.
“Not that we think it’s gotten any worse or anything like that — we just want to see how far it reaches,” Carden said.
By the numbers
• 0.4 milligrams per kilogram the state limit for mercury concentration.
• 1.67 mg/kg average mercury concentration among tested walleye in Lake Glenville.
• 0.96 mg/kg average mercury concentration among tested walleye in Santeelah Lake.
• 0.63 mg/kg average mercury concentration among tested walleye in Fontana Lake.
Source: N.C. Department of Environmental Quality data sheet
For a current list of mercury advisories in North Carolina, visit epi.publichealth.nc.gov/oee/fish/advisories.html