Okla. Stat. tit. 11 § 37-221
Any owner of real estate proposed to be assessed may, at or prior to the hearing on the apportionment, file his objections in writing against the validity of the assessment roll and proposed assessment, setting forth the nature thereof, and shall have full opportunity to be heard. The governing body shall make such adjustments as may be just and proper. Any and all objections to the amount and validity of the assessments shall be deemed waived unless presented at the time and in the manner herein specified. At the hearing on the apportionment, or any adjournment thereof, the municipal governing body may review and correct the apportionment and raise or lower the same as to any lots or tracts of land, as it shall deem just. The governing body by resolution shall confirm the apportionment and assessment as so revised and corrected by it. The determination by the governing body of the existence and extent of special benefit to each tract or parcel of land in the district is hereby declared to be legislative in nature, and shall be conclusive upon the property owners and upon the courts.
Okla. Stat. tit. 11, § 37-221