This part shall be liberally construed to promote the public welfare by irrigating lands, improving the existing water supply for the lands or providing new means or methods of water supply, or constructing and completing dams, reservoirs, canals, drains, structures, mechanical devices, levees, dikes, barriers and the use of any pumping equipment, pipelines, or other works or a combination of any or all of the same specified in the petition to be utilized for the preservation or operation of any irrigation system constructed, or proposed to be constructed, for the purpose of irrigation.