Karst aquifers are particularly vulnerable to surface pollution. Unlike sandstone aquifers that sit underneath thick layers of rock and sediment that allow filtering of pollutants, they are made of hard rock such as limestone and gypsum, creating a “super-highway” to the subsurface, she said.
“They are uniquely easy to pollute,” she said.
But that same rapid movement that makes Karst aquifers so susceptible to pollution can also help restore them.
Once a source has been identified and the pollution cleaned, the caves – and the life inside – will recover, said Elliott, the cave biologist with the Missouri Dept. of Conservation.
Elliott points to Hidden River Cave in Kentucky, a popular tourist attraction that was closed in 1943 because it was polluted by municipal sewage and wastes from a creamery and chrome-plating plant. By the mid-1980s, a new wastewater treatment plant was built, and by 1995, many of the animals such as cavefish and crayfish that had vanished returned to the section that was once heavily polluted.
“The cave no longer stinks, and we have tours again,” said Aley, the groundwater hydrology expert at Ozark Underground Laboratory. “When the water was so polluted, there was no life. Cave fish and crayfish were gone. We now have both back. This is a success story.”
That’s the desired outcome for those working to restore Beacon Cave, its underground streams and the waterways it feeds. The problems, however, persist.
The rural West Virginia cave is popular with climbers and valued for its underground stream as well as a slow-moving whirlpool.
Tests of the Bluestone River watershed conducted in July by the U.S. Environmental Protection Agency found that PCB concentrations are dropping, but they still exceed state water standards.
Both West Virginia and Virginia have issued advisories against eating fish caught in the river near the cave.
“The next step is for all of us to figure out if there were other historical sites that are somehow still contributing to the problem,” said Shelley Williams, an environmental specialist with the Virginia Dept. of Environmental Quality.
Schaer, the West Virginia geologist, said he believes buried drums from the long-gone electric manufacturing plant could still be polluting the cave.
Michael Towle, the federal EPA on-scene coordinator at Beacon Cave, agrees there could still be a source of PCBs underground, “in the cave itself perhaps.” But he said it’s a large, complex watershed, so finding it won’t be easy.
“A lot of this stuff has long since been buried, filled over and gone from most people’s memory banks,” he said, “so it may remain hidden forever.”
This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.