It might seem that the cave is isolated from the surface world – that the things that happen on the surface would have no effect on the cave. However, that is not entirely true. The changes inside Jewel Cave are usually so slow that the average person would not notice, but changes do occur, especially where moisture is able to seep from the surface into the underlying cave passages.

Increased moisture can cause the formations to grow faster, or it can erode them away. Forested areas above Jewel Cave receive less moisture than open, grassy areas. This is because trees take up much more rainwater than grasses do. When the surface of Jewel Cave was heavily forested with ponderosa pines, less moisture got into the cave. The Jasper Fire killed many of the pine trees, leaving the area open for grassy meadows. As a result, more rain water is expected to enter the cave, causing more changes.

The fire opened up the meadows to native plants such as blanketflowers, purple coneflowers, and western wheatgrass. Unfortunately, the fire-disturbed land also encouraged the growth of exotic plants such as mullein and Canada thistle.

Jewel Cave National Monument employs a “weed crew” to manually remove these unwelcome invaders. This means cutting the plants or pulling them up by their roots. The Monument does not currently use chemical herbicides on the plants because these could filter down along with the water into the cave, and the National Park Service strives to maintain natural water quality.

Many people, even those in big cities, get their drinking water from underground aquifers or rivers. Spraying herbicides or pesticides on the ground, dumping oil onto your driveway, or just pouring out chemicals like used cleaning fluid . . . all of these have the potential to affect the quality of the water you drink.