There are some eye-raising National Park Service water quality reports from the 1990s concerning Gap Creek, which flows through Cudjo’s Cave (or, Gap Cave).
Chromium was found in the creek in measurements up to 70 ug/L (which is equivalent to 70 parts per billion) between the years 1991 to 1996.(1) This is nearing the EPA’s maximum contaminant level (MCL) for chromium in drinking water, which is 100 ppb.
The National Park service tells us that:
Rivers once flowed through the upper chambers of Gap Cave–and Gap Creek still flows through the lowest level of the cavern. Water flowing from the cavern was used to power several mills and the machinery at the Cumberland Iron Furnace in the 19th century. The creek was dammed inside the cave in the 1800’s to create a reservoir that still supplies the towns of Cumberland Gap and Harrogate, Tennessee with drinking water.(2)
When contaminant levels are approaching the maximum levels set by the EPA, and the water supply is a source of community drinking water, it would be reasonable to expect the continued monitoring of contaminant levels in Gap Creek. However, Jennifer Beeler, the Cumberland Gap National Park’s Resource Management Specialist, indicated the water quality reports stopped when the Tunnel construction ended:
That work was done during the tunnel construction with funding from that particular construction project. After the tunnel was completed that degree of funding for water quality work was no longer available. We do basic water quality work each month like e. coli, temp, dissolved oxygen, conductivity, ph, turbidity etc, but that is it right now.(3)
Remember when the Middlesboro Tannery was blamed for chromium found in Yellow Creek? Interestingly, it would have been impossible for the tannery to contaminate Gap Creek:
Gap Creek on the TN side of the park comes from Gap Cave, flows through the town of cumberland Gap than Tiprell and then eventually empties into the Powell River. Little Yellow Creek in the park goes into Middlesboro, flows into Yellow Creek and then eventually into the Cumberland River. So the two are not connected at all.(3)
Another possible contaminant of concern in Gap Creek is manganese. Overexposure can be responsible for symptoms similar to Parkinson’s Disease, most notably muscle tremors and other neurological damage. Manganese toxicity can also be misdiagnosed as Lou Gehrig’s disease or multiple sclerosis. Children are especially susceptible to manganese toxicity. Currently, the EPA has established a “health advisory level” of .3 mg/L, or, 3 parts per million. However, in 1996, a report by the EPA,
in developing an oral reference dose for manganese based on dietary intake, mentions an epidemiological study in Greece that showed an increase in neurologic effects such as weakness and fatigue, disturbances in gait, and neuromuscular effects, in people whose drinking water contained 1.6 to 2.3 mg/L.(4)
The water quality reports for Gap Creek, where the communities of Cumberland Gap and Harrogate obtain their drinking water, show up to 210 parts per billion, or, .21 mg/L on December 1, 1991 and 270 parts per billion, or, .27 mg/L, manganese on March 23, 1993.(1)
(1) STORET Central Warehouse, EPA.
https://ofmpub.epa.gov/storpubl/storet_wme_pkg.Display_Station?p_station_id=CUGA_CPSU_GC4&p_org_id=11NPSWRD
(2)Cave Handout, National Park Service.
https://www.nps.gov/cuga/learn/nature/upload/cave-handout2.pdf
(3) Email communications, June 23 2015, with Jennifer Beeler, National Park Service.
(4) Drinking Water Notification Level for Managanese, California EPA State Water Resources Control Board.
http://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/Manganese.shtml