Understanding the connection between the cave and the land that is over it is difficult. But we do know that water is the critical factor. In recent years the park has been exploring the connections between the surface and the cave and the role of water. This water is not only important to the development and protection of the cave, it is also our ground water - the water we drink.
Having the visitor center over the cave influences more than just the flow of water. Each year, more than one million gallons of sewage flows through sewer lines from the visitor center to the sewage treatment area. Some of these were installed in the 1930's when the buildings were constructed.
In the early 1980's some of the pipes were slip-lined. During this process lengths of plastic pipe were inserted into the old lines and the flow was diverted into the new pipe. In 1999, using a special video camera, park managers monitored the lines. They discovered that not many of the lateral lines had been slip lined, and some pipes were broken.
It is difficult to measure whether sewage is leaking into the cave. However, any additional nutrients could alter the cave environment. Because no rivers or streams flow into the cave, Wind Cave is nutrient-poor. Nutrient-rich sewage would add an energy source and could change the biota of the cave.
The solution to this problem was to replace the entire sewer system with dual-contained pipes. These are pipes within pipes with leak detectors in the outer pipe. If a leak is detected, the system can be repaired before any sewage escapes from the second pipe. This major project was completed in 1999 to protect not only one of the world's most outstanding caves, but to protect the water that travels through it.