RESOURCE RAMBLINGS Vol 6. No. 5
Wind Cave National Park Resource Management News Briefs May 2008
Wind Cave Dye Trace (A.K.A Turning the Lakes Green)
At its lowest point, Wind Cave intersects the water table of the Madison aquifer, resulting in a group of subterranean open water bodies, known as “The Lakes.” Of the known 300 caves in the Black Hills of South Dakota, Wind Cave is the only cave known to have these water-table lakes, which provide a rare opportunity for hydrological and biological research. The Madison aquifer, which is The Lakes’ water source, is the subject of numerous scientific investigations because of its complex hydrological processes compounded with its regional importance as a water source.
Numerous hydrological studies indicate potential for significant water-quality impacts to the cave. For example, previous dye tracing indicated a hydrologic connection from Beaver Creek to groundwater (the park well) in the Madison aquifer. Arsenic, which is toxic to a variety of microorganisms, has occurred at levels higher than EPA drinking water standards in cave water and the park’s well #2. Map of Wind Cave with locations of study sites.
Also, Madison aquifer water levels may be a critical factor for cave biota because declines would reduce the size of, or eliminate, The Lakes, which collectively are the largest water body in the cave. The NPS-Water Rights Division has stated that a proposed groundwater withdrawal near the park for a new water system has the potential to impact park resources. Declines of more than 70 feet as a result of the new water system are possible, however a mere 40-foot decline would eliminate The Lakes completely, which may never have occurred in geologic history. Numerous other land-use practices in the rapidly developing area surrounding the park have high potential to affect the park’s water quality.
The purpose of this qualitative dye trace was to improve upon our understanding of the hydrologic connectivity of the three bodies of water within the cave (What the Hell lake, Rebel River, and Calcite Lake) and potentially the two park wells.
On February 26th of this year, four liters of Fluorescein dye were poured into What the Hell Lake within Wind Cave. Dye receptors (small packs of charcoal in screen mesh) were placed in Rebel River and Calcite Lake to detect if the dye is passing through the site. On this same trip, a reporter and photographer from South Dakota Public Radio and TV were along filming for a segment that will air sometime in May (Times when this will be broadcast will be posted). Dye trace being poured into What the Hell Lake.
On March 25th we returned to the Lakes to change out the dye receptors. What the Hell lake still contained much dye, with the almost half of the lake still being bright green. We discovered that Rebel River was running bright green, thus proving that water from What the Hell was flowing to this site. The lab results later confirmed this. Calcite Lake appeared to be slightly green, but not enough to confirm it just based on our visual sighting. However, the lab results confirmed that indeed the dye had made its way to Calcite Lake as well.
Samples taken from the two park wells on March 20th showed no dye present. Continue monitoring will be done at both wells as the dye may show up there at any time.