The purpose of this chapter is to establish requirements for the grant and loan program covering rehabilitation, improvement, and construction of agricultural water supply facilities pursuant to Referendum 38, chapter 43.99E RCW. The department shall provide grants and loans to applicants for water supply facilities for agricultural use alone or in combination with fishery, recreational, or other beneficial uses of water. In this regard, an objective of providing state assistance to public bodies engaged in irrigation shall be to assist those entities in improving their efficiency of water use beyond current levels.