This can't be good.
    A strain of E. coli has been detected in the groundwater of the "Historic" section of Mammoth Cave National Park, raising concerns over just how it got in there.
    The bacteria was found October 26 when a Western Kentucky University researcher was running chemistry tests on water taken from Charon's Cascade, which is found below River Hall in the cave. Park officials retested the waters on October 30, and while E.coli levels in Charon's Cascade had fallen a bit, other locations measured in the Historic section produced levels that exceeded acceptable public health levels.
    On Halloween, another round of tests showed that safe levels had returned to all the sections tested. Still, park officials have opted to temporarily close the Historic section where potentially contaminated water could drip on cave visitors.
    "Now that we know of the problem, we are exploring every possible source," says Mammoth Cave Superintendent Patrick Reed.
    With the Historic section closed, tours are being diverted to the Frozen Niagara section of the cave, which is three miles from the Historic section and in a different drainage basin.
    While initial testing has indicated that the contamination source might be water flowing flowing off parking lots, officials plan to keep testing until they pinpoint the source. They also plan to test the bacteria to determine whether it's a strain found in wildlife or humans.