SINKING WATERFALLS AND GIANT SPRINGS, DELINEATING RECHARGE AREAS IN THE LITTLE SEQUATCHIE WATERSHED OF SOUTHERN TENNESSEE (Invited Presentation)

The Little Sequatchie River drains the eastern escarpment of the Cumberland Plateau and is the largest tributary to the more intensely studied Sequatchie Valley. The hydrology of the 120 mi² valley has been largely altered by karst processes which has caused the majority of the streams to sink at the contact between the Mississippian Pennington Formation and the underlying Mississippian Bangor Limestone. The resulting karstification has created spectacular swallets, significant cave systems, and large springs where the sinking streams resurge. Since early 2022, dye tracing has sought to map the karst groundwater pathways in the Little Sequatchie valley in order to better understand the recharge areas that impact water quality and quantity for springs that provide critical habitat for Threatened and Endangered Species, such as the Royal Marstonia (Pyrgulopsis ogmorhaphe) and Sequatchie Caddisfly (Glyphopsyche sequatchie). Additionally, the Little Sequatchie River provides water for agricultural practices and serves as a drinking water source for nearby communities. Thus far, a total of this work has delineated recharge areas for five major springs, ranging from 1.7 to 34.4 mi² in area. Many of the dye traces have remained sub-surface for significant distances, from injection location to recovery site, with karst groundwater travelling up to 8 mi before resurfacing. These traces have also had rapid travel times, often travelling thousands of feet to miles per day. Work continues in the Little Sequatchie valley and future aspects of the project will focus on delineating a recharge area for nearby Jasper Blue Spring. Jasper Blue Spring is a large spring utilized as a drinking water source for a nearby community and is mapped to 144 ft-deep and 2.46 mi-long. The goal of this project is to provide scientific data that private landowners and state and federal partners can use to make informed decisions on the protection and preservation of this unique and vulnerable karst system.