Area water experts haven’t figured out why a substance banned decades ago seems to be showing up in local lakes. Nor, more importantly, are they sure how to fix the problem.
Earlier this month, North Carolina released fish consumption advisories upstream of Lake Wylie, finding fish with high concentrations of polychlorinated biphenyls. The non-organic material once found wide use as a coolant in power generation, refrigeration and industrial areas. It was banned in 1979 for most commercial uses because of adverse health effects.
Yet in the past few years, more health advisories on the Catawba River have been issued to PCB levels. Current advisories include limits on striped bass in Lake Norman, channel and blue catfish in Mountain Island Lake, largemouth bass in Lake Wylie and largemouth throughout the entire South Carolina stretch of the Catawba River, including Lake Wateree.
“There’s been no source point identified yet,” said Mark Hale with North Carolina’s Division of Water Quality. “There are some studies being planning to identify that.”
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North Carolina is updating a basin-wide water quality report from 2008. Combining testing stations for micro invertebrates and fish tissue, the Catawba has more than 150 locations looking at organism health.
Hale said insect and fish testing results in the river will be “slightly improved” in the 2013 report compared to 2008. Yet there are more fish advisories. One reason is more tests are being done for PCBs “not targeted that often in the past,” Hale said.
“It’s hard to recommend strategies to eliminate them, or to know where they’re coming from,” he said.
South Carolina issued its 2013 basin-wide water quality assessment. Testing occurred every other month last year at almost 80 stations along the Catawba. Partnerships for additional testing, including with the Catawba Indian Nation, are being looked at by the health department’s Bureau of Water.
Program manager David Chestnut said Catawba reservoirs, as opposed to true lakes, are “big settling ponds” for PCBs that escape into waterways. They don’t break down, he said, and the longtime ban means there isn’t an active location to be shut down.
“There probably isn’t a localized source to be identified anymore,” Chestnut said.
There all along?
The most likely explanation isn’t undiscovered sites are leaking more PCBs into the Catawba, but better testing is picking up what was a problem all along. PCBs “could’ve been there in those same levels of contamination for who knows how long,” Hale told members of the Catawba-Wateree River Basin Advisory Commission an April 19 meeting in Rock Hill.
Other factors can contribute. A 1979 Environmental Protection Agency press release detailing the federal ban and phase out of PCB use states the chemicals were used for nearly 50 years and 150 million pounds were “dispersed throughout the environment, including air and water supplies” with another 290 million pounds in landfills. Stockpile sites could remain.
PCBs also stick to sediment and can return through plants growing in it, stirring of the sediment or contaminated fish dying and restarting the food cycle.
What can be done?
Experts aren’t sure what can be done to reduce PCB content in fish. So they’re focusing on continued testing and public advisories. One possible solution is to let untainted sediment bury the older, PCB-laden sediment.
“As much sediment as there is flowing into, say, Lake Wylie, it should be going down,” advisory group Chairman Rick Lee said of PCB levels.
But lake fill-in harms recreation and aquatic wildlife. Dredging can reverse sedimentation problems, but it can increase PCB levels on the lake’s bottom. Commission members brainstormed everything up to testing the insects eaten by the fish see where the cycle breaks.
“We’re going to have to do something or we’re just going to say, you can’t eat the fish anymore,” said Commissioner Smitty Hanks, also a Lake Wylie Marine commissioner. “How do we break the chain? I don’t know.”
As for testing, both states want more but aren’t sure how far it can be expanded. Single fish tissue tests can cost $1,000 or more. In South Carolina, the lab can only test six to 12 fish per month, Chestnut said.
“It’s a big limitation,” he said.