The bureau of Reclamation believed it necessary that basin-wide studies of stream pollution be conducted to establish base data for use in planning maximum water utilization; to document the extent and nature of existing pollution; and to record general standards of water quality. Sanitary engineers detailed to the Lower Platte River Basin Study by the Nebraska State Health Department and the Public Health Service included the Niobrara River Basin and Ponca Creek Valley in their investigations. A mobile laboratory unit was moved to Ainsworth, Nebraska, in the Niobrara River Basin, June 8, 1949. The report contains reviews of State water pollution control laws, laboratory results, presentation of data, discussion, conclusions and recommendations. An appendix is included for individual laboratory and flow data.