The accompanying figures depicting various considerations of coliform-type bacteria concentration in the Missouri River are based upon data furnished through the cooperation of water treatment plant operators at Omaha, Nebraska; Council Bluffs, Iowa; St. Joseph, Missouri; Kansas City, Kansas; Lexington, Missouri; and Boonville, Missouri. Operators at Omaha, Council Bluffs, and Kansas City, Kansas, made available their routine daily analysis results. Personnel at the Missouri plants began daily analyses in February 1955 at the special request of the Missouri Division of Health and Public Health Service. Collection of data at the six localities is continuing. This report concerns the period February 1955 to December 1956.