When the official plan is filed with the secretary of the district, he shall at once notify the board of appraisers, and they shall thereupon proceed to appraise the benefits of every kind to all property within or without the districts which will result from the organization of said district and execution of the official plan; provided, however, that in the case of a district composed in whole or in part of municipal corporations, state or federal institutions, and/or political subdivisions, the board of appraisers may, in lieu of appraising benefits against each separately owned parcel of realty situated within the same, appraise the benefits as a whole to all property situated within the boundaries of said municipal corporation, institution and/or political subdivision. In such event, the benefits appraised as a whole shall be considered as benefits to the municipal corporation, institution and/or political subdivision. It shall be the duty of the governing body of the said municipal corporation, institution, and/or political subdivision to collect assessments levied on the appraisal of benefits, as provided in the Conservancy Act of Oklahoma. Provided, however, that to the extent legally permissible, as now or hereafter provided, such municipal corporation, institutions and/or political subdivisions may pay such portion of any assessments levied under the provisions of this act from funds and revenues otherwise collected and held by them, to the extent such manner of payment is deemed desirable. In the progress of their work, they shall have the assistance of the attorney, engineer, secretary and other agents and employees of the board of directors. The board of appraisers shall also appraise the benefits, if any, accruing to cities, villages, counties, townships and other public corporations, as political entities and to the State of Oklahoma.
The appraisers in appraising benefits shall consider only the effect of the execution of the official plan. The appraisers in making appraisals of benefits shall give due consideration and credit to any other works or of the systems of reclamation already constructed or under construction which form a useful part of the work of the district according to the official plan.
Okla. Stat. tit. 82, § 602