Rivers, streams, springs and ponds can all be found within the park. These waterways play an important role in connecting the varying ecosystems in the park through a vast hydrological network. At the same time, these varying waterbodies are also a critical habitat to hundreds of species of plants and animals.

A river channel with logs on the banks
Woody debris line the banks of the Green River adding a diversity of habitats.

NPS Photo/ Deb Spillman

Green and Nolin Rivers

Traveling over 30 miles thorough the park, the Green and Nolin Rivers are some of the most biodiverse rivers in North America. Approximately 87 species of fish and 58 species of freshwater mussels call the rivers home. In addition to the freshwater mussels, there are nearly 200 species of bottom-dwelling macroinvertebrates in the rivers. For these biological reasons, the Green River has been designated an "Outstanding Resource Water" by the state of Kentucky.

The Green River is the base-level stream for the Mammoth Cave System and has a crucial influence on the cave aquatic community. Water from the river often backflows into the cave system transporting sediments and carrying nutrients and food supply into the cave for the many cave species.

Most of the food energy in the rivers comes from the forest ecosystem. Washed-in organic matter, ranging from leaves and whole trees to the bodies of creatures great and small, provide organic input to the rivers. Complex biological communities in the rivers process the organic matter and the food energy propagates up the food web.

Water falling off of a rock ledge into a pool of water.
Water falls from the rock ledges above River Styx Spring.

NPS Photo/ Deb Spillman

Springs and Seeps

Typical of karst topography, the park and surrounding area is dotted with sinkholes. As the sinkholes south of the park drain, the surface water flows underground through caves within the Mammoth Cave plateau eventually emerging through springs along the Green River. Groundwater in this area can travel for over 7 miles from the sinkhole plain, passing through many parts of the Mammoth Cave system, as well as smaller caves in the area. The groundwater in the cave is home to eyeless creatures, such as crayfish, cave fish, cave shrimp and many more species of aquatic life.

Where numbing-cold groundwater bubbles up to the surface and directly into a river, these springs may be referred to as a “blue hole”, or a gravity "falling" spring. Seeping springs may not flow directly into a river, instead contributing to swamps or other waterways. These different types of springs and seeps not only support the Green and Nolin rivers, but also create their own ecosystem bridging the surface and the subterranean. The most notable springs in the park are River Styx Spring, Echo River Spring, and Turnhole Bend Spring.

A pond with water plants covering the surface
Sloans Crossing Pond provides an excellent area for wildlife watching.

NPS Photo/ Deb Spillman

Ponds and Upland Swamps

Due to the vast karst landscape found throughout the park, water often drains below the surface before large ponds or lakes can form. However, some instances of ponds and upland swamps do exist in the park. Sloans Pond, located along the Mammoth Cave Parkway, is one prime example.

Here, pooled water and shallow swamps provide habitat to a myriad of plants and animals. Water loving plants such as cattails stabilize the banks around the pond and provide filtration as water moves into the pond from the surrounding landscape.

Crayfish and dragonfly larva can be found hiding in the leaf litter in the shallows, while several species of turtles may be seen basking on a log on a sunny day. Even a resident Canada goose has found a safe haven among the tall grass and reeds on a small island near the far end of the pond.

The diversity of plant and animal life found in the small ponds and upland swamps found in the park are evidence of the value of water. In the otherwise rocky landscape of the park, these damp ecosystems allow for a wider abundance of wildlife to thrive.

Last updated: November 3, 2021

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Mammoth Cave , KY 42259-0007


270 758-2180

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