No change of any grade previously established by a municipality shall be made without making due compensation to the owners of abutting property for any damage thereby caused to permanent improvements erected on the abutting property with reference to the grade previously established. However, the failure to make such compensation shall not invalidate any assessments on the property chargeable with costs of a grade change as provided by law on street improvements.
Okla. Stat. tit. 11, § 36-111