Buena Vista county is located in northwest Iowa in the third tier of counties south of the Minnesota state line and the third tier east of the Sioux river, which forms the South Dakota state line. It is entirely in the Wisconsin drift soil area and the soils are mainly glacial in origin.
Stevenson, W. H. and Brown, P. E., "Soil Survey of Iowa, Report No. 16—Buena Vista County Soils" (1920). Soil Survey Reports. 18.