USGS geologic Mapping and karst research in the Ozark National Scenic Riverways, Missouri, USA

The Ozark National Scenic Riverways (ONSR) was created in 1964 to protect 134 miles of the Current River and its major tributary, the Jacks Fork, that are located in south-central Missouri (fig. 1). The park includes numerous large karst springs including Big Spring, by flow volume this is the largest spring in the National Park system. The National Park Service (NPS) administers a narrow, nearly continuous corridor of land adjacent to the two rivers. Base flow for the rivers is chiefly supplied by groundwater that has traveled through the karst landscape from as far as 38 miles away from the spring (Imes and Frederick, 2002). The watershed is vulnerable to pollution, but the area remains largely rural with few industries. The springs and rivers provide habitat for numerous aquatic species as well as recreational resources for floaters, fishermen, and campers. The ONSR is a major cave park with hundreds of known caves and diverse in-cave resources.