Iowa Code § 589.19
If the title to real estate has been conveyed more than ten years earlier, by the sheriff of a county pursuant to sheriff 's sale under the foreclosure of permanent school-fund mortgages to the state, or to the state for the use of the school fund, or to the county for the school fund; and the land has been sold under authority of the board of supervisors of the county and conveyed under its authority, more than ten years earlier, and the full purchase price paid and credited to, and used by, the county for the permanent school fund of the county, all right, title, or interest of the state in and to the real estate is relinquished and quitclaimed to the purchaser or the purchaser's grantees forever, and the title confirmed in the purchaser, or the purchaser's grantees insofar as the erroneous conveyance is concerned.
Iowa Code § 589.19