(a) Any water improvement district, water control and improvement district, levee improvement district, county, city, town, or other political subdivision of the state may contract to contribute to the cost of the construction of drainage, flood-control or water-supply improvements, or the changing of land elevations which need correction. The improvements to be constructed may be outside the contributing district, municipality, or other political subdivision of the state, and may be located outside the state or the United States.
(b) The works may be constructed by any agency.
(c) The contribution shall be proportionate to the benefit which the contributor will derive from the proposed improvements.