Konza Prairie Research Natural Area (KPRNA) is an 8616 acre (3487 ha) tract consisting mostly of native tallgrass prairie, and is located in southern Riley county in the Flint Hills of eastern Kansas. Following the leadership of L. C. Hulbert, The Nature Conservancy (TNC), with money provided by Katharine Ordway, set aside KPRNA during the period 1971 to 1979. Under ownership and lease agreements between TNC and Kansas State University, the site is managed for research by the Division of Biology. Research activity has been increasing steadily on KPRNA since 1977 when it was set aside for ecosystem research. The core of the management involves experimental manipulation of watersheds with controlled fire (several replicated intervals between fire from 1 to 10 years plus unburned references) and with native and domestic grazers (planned reintroduction of bison and cattle to different treatment watersheds in November 1987) (Hulbert, 1985). The tallgrass prairie ecosystem once covered about 7% of the U.S., i.e., most of the Midwest (Kiichler, 1964). In most states where the type dominated the presettlement landscape (Illinois, Iowa, Indiana, southern Wisconsin, southern Minnesota, northern Missouri, eastern Nebraska, eastern North Dakota and eastern South Dakota) the soils have been plowed and converted to grain production agriculture, among the most productive agricultural areas in the world. Not much unplowed prairie is left and the opportunity for watershed level work under unplowed conditions does not exist at any other tallgrass prairie site in the United States. The National Science Foundation included KPRNA in its network of sites dedicated to long-term ecological research (LTER). That research has been underway since late 1980. Kings Creek, a central tract of 2619 acres (1060 ha) on KPRNA, was added to the U.S. Geological Survey's network of benchmark watersheds in 1979 (Biesecker and Leifeste, 1975) and the drainage area has been identified as a fixed station in the Survey's pilot research program termed National Water Quality Assessment (NAWQA) (Stamer, pers. comm.).