ZIP 51531 falls in Shelby County, Iowa, where we hold 126 septic-related documents. We have not classified septic-versus-sewer status for this county, and we do not have a per-ZIP parcel count -- see the county page for what we hold and where the records are kept.
ZCTA 51531 is not entirely inside one county. Land-area share is from the 2020 Census ZCTA-to-county relationship file.
| County | Land in this ZIP | Documents held | On septic (county) | On sewer (county) |
|---|---|---|---|---|
| Shelby County, Iowa | 79% | 126 | — | — |
| Audubon County, Iowa | 21% | 54 | — | — |
Land-area overlap is from the 2020 Census Bureau ZCTA5-to-county relationship file, not an estimate of ours. Parcel and document counts are rows we hold, not a survey of every property in the ZIP. Last verified 2026-09-01.
We have not measured septic-versus-sewer status for this county yet.
ZIP 51531 spans 2 counties: Shelby County, Iowa, Audubon County, Iowa.