The nationwide need for hydrologic information characterizing conditions in mined and potentially mined areas has become critical with the enactment of the Surface Mining Control and Reclamation Act of 1977.This report is for Area 39 in eastern Kansas and western Missouri, which is one of 7 hydrologic reporting areas in the Western Region of the Interior Coal Province.The report, consisting of a brief text accompanied by a map, graph, table, or other illustration, portrays the general geographic, geologic, and hydrologic environment of the area.Area 39 has an area of about 10,500 square miles and includes all or parts of 13 Kansas counties and 14 Missouri counties.Major streams draining the area are the Marais des Cygnes (Osage), South Grand, Little Osage, Blackwater, Blue, and Little Blue Rivers, which are tributaries of the Missouri River.Hydrologic data for Area 39 are stored in computer files accessible through the National Water Data Exchange (NAWDEX).