What is Wynona soil and how does it affect Oklahoma foundations?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: Wynona is a very deep silty soil on flood plains of eastern Oklahoma, including streams around Tulsa. It is somewhat poorly drained, floods occasionally in winter through midsummer, and holds a perched water table about 2 feet down from November to April. Flood exposure, wet ground and soft stream-laid layers are the main foundation factors on Wynona.

Where does Wynona soil occur?

The USDA Natural Resources Conservation Service (NRCS) keeps an Official Series Description (OSD) for each named soil. Wynona was established in 1975 in Osage County, Oklahoma, and its type location is about 4 miles south and 1 mile west of Skiatook ¹. It was previously included with the Verdigris series ¹. The OSD lists it in MLRAs 84A, 85, 112, 117 and 118 of eastern Oklahoma, southeastern Kansas and southwestern Missouri, and calls it moderately extensive ¹.

Wynona forms on nearly level to slightly concave flood plains, in silty alluvium (stream-laid sediment) ¹. That places it on the Quaternary alluvium along creeks and rivers in the Tulsa Metro and East-Central (Arkoma) regions. Most Wynona land is tame pasture, with some areas cultivated or kept as native range and hay meadows ¹.

What are Wynona soil's key properties?

"Epiaquolls" are dark-surfaced soils with a wet (aquic) moisture regime; in Wynona the wetness comes from a perched water table ¹. The "g" in Bg stands for gleyed, the gray colors that form when soil stays saturated, and Wynona shows redox mottling in both its topsoil and subsoil ¹.

The OSD names Verdigris as a competing series that is well drained, and Osage as an associated soil with a clayey control section and high shrink-swell ¹.

What does Wynona soil mean for foundations?

Flooding

Wynona floods occasionally for very brief periods from January through July in normal years ¹. FEMA's Flood Map Service Center can be searched by address for the flood map covering a lot ⁴. See creeks and flood history.

Perched water and wet crawl spaces

A perched water table is a temporary saturated zone held up above slower-draining soil. On Wynona it sits about 2 feet down for half the year ¹. HUD's soil guide identifies water table depth, natural drainage and seepage as key controls on soil moisture ⁵. Shallow seasonal water is the setting for crawl space moisture and wood decay, perimeter wetting heave and water pressure on below-grade walls.

Soft, wet sediment

Saturated, stream-laid silts and clays are the soils covered on soft soil consolidation. Some Wynona profiles also contain buried former surface layers below 40 inches, a sign of repeated deposition ¹.

Shrink-swell and drainage

NRCS rates shrink-swell by linear extensibility, from low (under 3 percent) to very high (more than 9 percent) ³. Wynona's control section is fine-silty, with 27 to 35 percent clay, while associated Osage has a clayey control section ¹. The rated value is in Web Soil Survey ². The ASCE homeowner guide recommends at least 3 inches of fall over the first 5 feet and downspouts that discharge at least 3 feet from the foundation ⁶.

Related

• Verdigris soil
• Osage soil
• Groundwater and perched water
• Crawl space encapsulation
• Soil Series Index