The county commission may, if it determines after notice and hearing, in the same manner as is provided for establishment of such a district that a drainage district organized by the county commission under this chapter has been inactive for at least ten years, make an order calling for the dissolution of the inactive district and the distribution of any funds of the inactive district, by the county treasurer, to any subsequently organized district or districts incorporating all or part of the territory of the inactive district on a pro rata basis of any funds of the inactive district; and if any portion of the inactive district incorporated under this chapter is not within a subsequently organized district the county commission shall order the county treasurer to make refunds on a pro rata basis to the present owners of the property on which the tax was levied as their interest appears of record, and the county treasurer shall have authority to draw checks against the funds of the district for this purpose. After all the funds have been distributed, the county commission shall declare the district dissolved. In prorating, the assessed valuation of the various tracts of land shall be the basis on which the proration is made and the assessed valuation of the tracts involved for the year in which the dissolution is ordered shall be used.