BACKGROUND INVESTIGATIONS INTO MAQUOKETA CAVE WATER SOURCES IN EASTERN IOWA

Due to their complex natures, little research has been conducted on the source of water in midwestern caves. With funding from the Iowa Space Grant Consortium, ongoing investigations are being conducted by the University of Northern Iowa within Wind Cave National Park. To better understand the data collected in South Dakota, samples have been collected and analyzed from Maquoketa Cave State Park, near the border of Iowa and Illinois. Three sources were identified by park staff and sampled by the researchers. One source (Dancehall) travels in an open-air channel for hundreds of meters through a tall, vaulted cave. The second collection site (TD Spring) is a spring which trickles directly from the rock wall outside the lower Dancehall opening. The third site (Rainy Day) is an open-air stream in a much shorter, less ventilated cave. It is important to note that these three sampling sites are within 100 meters of each other yet have strikingly different chemistries. Indicating that the latter two sampling sites are fed by shallow, conduit water sources, the pH levels of both hovered near 7.5, while the Dancehall site consistently had a pH above 8.0. The difference in pH is in many cases indicative of limestone buffering, the process by which water becomes more basic due to time spent passing through the limestone bedrock of Iowa. It is likely that despite its open-air nature, the Dancehall water source is fed more by deep, diffuse flow than conduit flow. Conflictingly, the DO of this larger water source is higher on average than the DO of the other two Maquoketa sites studied. Ionically, both TD Spring and Dancehall samples have approximately 60% less Chlorine than Rainy Day. Both TD Spring and Dancehall also have significantly higher nitrate concentration than Rainy Day Cave. All sites have similar Sulfate concentrations when tested with an Ion Chromatograph. These data indicate that TD Spring and Dancehall Cave have more in common than they share with Rainy Day, but a definitive source of the water that feeds these three systems has not yet been nailed down. After the park, now closed for bat hibernation, opens again in the Spring, a dye tracing will be organized to more fully and definitively ascertain the ways in which these water sources are fed. This data will be used in the Summer of 2022 in the performance of a dye tracing at Wind Cave National Park.