Atlases for Howard County, Missouri, for the years 1876, 1897, and 1967 were utilized to prepare a map illustrating the extent of riparian land under the chain and unity of title theories for a ten mile strip of land immediately west of the east boundary of the county and lying north of the Missouri River. The costs of irrigating tracts at different locations were calculated. It was concluded that the unity of title theory--classifying all land as riparian which adjoins a riparian source, is contiguous, and within the same watershed--was the preferred legal theory because it provided the needed flexibility for facilitating water useage on those tracts most productive at the margin. It was also concluded that permitting water to be used on land other than that classified as riparian is economically feasible and in some cases the minimum cost method of providing irrigation water.