Signs of an above-ground sewage spill that occurred at Mammoth Cave National Park back in May have been detected inside the cave system, but is not thought to be a threat to visitors.

Back on May 27 some 5,000 gallons of sewage leaked from pipe lines, and about 3,000 of that was initially recovered, according to park officials. While check dams were installed to slow drainage of the sewage following rain storms, recent tests detected levels of E.coli in waters from the Cataracts, a waterfall near the route of the Violet City Lantern Tour.

“The appearance of the spill may have disappeared on the surface of the park, but it is important that we trace it and see how it may impact resources underground,” said Russ Runge, the park's acting superintendent. “In a karst area, everything that happens on the surface affects the cave below. At this point, it appears that pulses of storm-water mobilize residual sewage causing elevated E.coli levels in certain areas for short periods after storms.

“Water samples collected at Cataracts, a waterfall adjacent to the Violet City Lantern Tour, showed elevated levels of E.coli," he said. “We will continue to run the tour because Cataracts is off the tour route, away from where visitors walk.”

The spill occurred along the Mammoth Cave Parkway and above the habitat of the Kentucky cave shrimp, an endangered species. Park staff are expanding the sampling area by collecting water samples at water table locations in the cave and at cave springs on the surface.