KARST HYDROGEOLOGY FEATURES OF THE COLLINS RIVER IN THE SAVAGE GULF AREA, SOUTHEAST TENNESSEE

The Collins River near McMinnville is a 67-mile-long (108 km) stream in the southeast portion of Middle Tennessee in the United States; it is known for its sports fishery, recreational paddling, and scenic qualities. It was also the inspiration for the foundation of the Tennessee Scenic River System. Less commonly known are the karst hydrology aspects of this river, where most of the sustained flow issues from the base of the Cumberland Plateau at the foot of the escarpment below the community of Beersheba Springs; an area known to canoeists as the ‘Blue Hole of the Collins’. The Collins River proper originates in the Savage Gulf State Natural Area, where the flow of three main streams in deep valleys or ‘gulfs’ carries water flowing off the Pennsylvanian Age sandstone and shale bluffs of the Southern Cumberland Plateau into the soluble limestones of Mississippian Age which underpin the bedrock of the escarpment. Owing to the generally inaccessible nature of the undeveloped and in some places pristine character of these tributary valleys, little is published about the karst features present in these drainages. The channels of the headwaters of the Collins River, plus the tributary Big Creek and Savage Creek valleys, all contain multiple swallets where surface flow abruptly disappears only to reappear further downstream in or adjacent to the cobble and boulder clogged valley floor. Raw water quality information recorded by the City of McMinnville for their water supply intakes on the Collins and Barren Fork Rivers show that during periods of little rainfall the Collins has markedly different alkalinity, hardness, and pH values than the Barren Fork, indicating a significant groundwater contribution.