Texas Natural Resources Code - NAT RES § 21.043. Lost Field Notes

(a) If the original field notes of an authorized survey are lost or destroyed, the owner or his agent may obtain a certified copy of the record from the county surveyor on making an affidavit of the loss or destruction and filing it in the office of the county surveyor where the survey was recorded.

(b) The certified copy shall be as valid as the original record and shall secure to the owner all the rights before the commissioner that the original would have secured.