Kentucky’s Mammoth Cave's hidden plumbing system allows rainwater to reach underground quickly through sinkholes, but these water routes can also carry sewage, chemicals and other pollutants into the cave

Kentucky’s Mammoth Cave has a vast underground water network fed by rainwater entering sinkholes and cracks in the limestone. The same rapid pathways that supply cave rivers can also carry sewage, chemicals, pesticides and other pollutants underground, threatening the cave’s fragile aquatic ecosystems.