A proposed project may be approved for assistance only if it is determined that the project substantially conforms to the California Water Plan, is engineeringly feasible, economically justified, and, if a loan is proposed, that there is reasonable assurance, commensurate with the need for the proposed project, that the public agency can repay it. The potential future growth and development of the area shall be taken into consideration in the calculation of the benefits for the determination of the economic justification of a proposed project. Such factors as the public health, safety, and welfare shall be taken into consideration in determining the need for a proposed project.