In all cases where the lands assessed for any water supply or any reservoir or reservoir capacity constructed or made available under the provisions of this chapter lie in whole or in part under any existing canal system, or are so located that the same can be irrigated through such canal system or any part or extension or enlargement thereof, the board of county commissioners of the county in which such lands, or any part thereof, are located are authorized to enter into a contract on behalf of such county, with the company, irrigation district, or individual owning or operating any such canal system under which such district, company or individual shall become the agency of the county for the distribution and delivery of such reservoir or other water to the lands of such county lying under or so located that they can be irrigated from such existing canal system, and as such agent of the county to provide for the operation and maintenance and repair of the irrigation works constructed or made available under the provisions of this chapter and authorizing such canal owners or operators to collect from the landowners under said canal system an operation and maintenance charge, toll, fee or assessment sufficient to pay the cost of such operation, maintenance and distribution including the cost of operating and maintaining the reservoir or the proportionate part thereof properly chargeable to such land, and to require the payment of such operation and maintenance charges as a condition to the delivery of such reservoir or other water supply and to withhold delivery of such reservoir or other water until all such operation and maintenance charges for past years have been paid, and when so provided in the contract between such canal owner and the county or when so ordered by the board of county commissioners, shall withhold the delivery of such water supply so provided or made available by the county under the provisions of this chapter, from any lands on which any instalment of the principal, or interest of the said liens provided for in this chapter, or the amount due the sinking fund as herein provided, or any assessment levied by the county for the purpose of paying any such instalment or annual interest charge or sinking fund remains delinquent, delivery to such lands, however, to be resumed upon payment of all assessments then due and payable or delinquent, but no part of the water supply provided or made available by the county under the provisions of this chapter shall be delivered to lands against which benefits have not been assessed.