Turnhole Bend Spring

Turnhole Bend Spring. Mammoth Cave National Park. , Turnhole Bend Spring, 75 feet below, is the third largest spring in Kentucky, draining 345km2 of the surrounding region into Green River. Water flow can range from 100 to 6,000 gallons per second. Much of this water originates from a large area of sinkholes south of the park boundary. Thousands of sinkholes drain water underground and flow through a multitude of cave passages. This water briefly emerges at the Cedar Sink, then continues its subterranean journey until converging at this point with Green River on the surface., The Green River, along with water from Turnhole Bend Spring, continues to flow outside the park, eventually supplying water for several communities. Park Service personnel monitor the surface and sub-surface rivers to ensure healthy water quality for the park's ecosystem as well as surrounding communities. , (aside:), 19th century riverboats once entered the spring to reverse their course along the river - hence the name "turnhole", (diagram captions:), ·The waters emerge at Turnhole Bend Spring to join Green River., ·The flow surfaces briefly at Cedar Sink., ·The waters continue below sandstone-capped limestone layers, forming caves as they go., ·Rain falling on the sinkhole plain drains quickly underground., ·Draining waters enter from below - not above - the river itself.