1. Delineation of flooding within the Ozark National Scenic Riverways in southeastern Missouri - Round Spring and Powder Mill Yale Public content 1990. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Map Distribution. English. Public. Missouri and Ozark National Scenic Riverways.