The county commission shall have control of the affairs of the county as such drainage district. No commissioner shall directly or indirectly be interested in any contract made by the county commission, save and except insofar as other land owners are benefited by the work constructed. They shall appoint and employ such agents and persons as they may deem necessary for the execution of the purposes expressed in this article, particularly operators of county controlled machinery and equipment, save and except they shall not become directly or indirectly employed by the county commission or by a subdistrict established by authority of this article. They shall have the right and authority to enter into contracts or other agreements with the United States government or any department thereof, with persons, firms or corporations, with the state government of any department thereof or with drainage, conservation or other improvement districts for cooperating or assisting in planning, constructing, maintaining, using and operating the work necessary to the execution of the policy adopted in this article and the purposes of this article. They may, upon written petition of the land owners, engage in or assist such owners in the location, construction or maintenance of any ditch, drain, terrace, embankment or outlet which may, in their discretion, be necessary to the accomplishment of the declaration of purposes expressed in this article. In the execution of the powers contained in this article, the county commission is authorized and empowered to use such machinery, equipment and materials as may be owned by the county or to provide by purchase, lease or rental such machinery, equipment and materials as may be necessary to accomplish the work to be done. By majority vote of the county commission, the county may lease or rent to an individual, a group of individuals or to any subdistrict the necessary machinery, equipment or materials for the necessary work; provided, that such lease or rental charges shall be on a fixed hourly basis and shall not be less than an amount sufficient to cover interest, average maintenance and amortization of the costs of such equipment as estimated by the county commission. The officers or directors of the subdistrict, as provided by the constitution and bylaws, shall collect from the individual owner or owners of the lands benefited an amount sufficient to pay the said lease or rental charges and all operating costs and expenses. Such amounts shall be collected in cash, in advance or as the work progresses, as agreed upon by the county commission and the officers or directors of the subdistrict. The constitution and bylaws of each subdistrict shall provide for a treasurer who shall be bonded at the expense of the subdistrict. He shall receive all funds collected by the subdistrict, pay all bills for operating costs and expenses, pay to the county treasury all lease or rental charges for machinery and equipment and make a proper accounting for all money received and disbursed. In case the county leases or rents such equipment to an individual or group of individuals not organized as a subdistrict, the lease or rental charges shall be paid as required by the county commission.