Grable and Percival soils are finer textured in the upper part, and Onawa soils are finer textured throughout. Grable soils occur on flood plains but are less undulating and occur further back from the river. Percival and Onawa soils occur on nearly level flood plains. Modale and Waubonsie soils are clayey below a depth of about 2 feet and occur on nearly level flood plains. Runoff is low.
Permeability is rapid or very rapid.
The soil floods unless protected by levees or dams. Native vegetation commonly is a thin stand of native grasses and sandburrs or cottonwood and willow trees. Cleared areas are in pasture or cropped to alfalfa, oats, soybeans, and wheat. Mainly along the Missouri River and other major streams in Iowa, Nebraska, and South Dakota. The series is of moderate extent.