The exercise of the powers granted to the water development authority by this article will be in all respects for the benefit of the people of the state, for the improvement of their health, safety, convenience and welfare and for the enhancement of their residential, agricultural, recreational, economic, commercial and industrial opportunities and is for a public purpose. As the construction, acquisition, repair or renovation of projects or infrastructure projects will constitute the performance of essential governmental functions, the water development authority shall not be required to pay any taxes or assessments upon any project or upon any property acquired or used by the water development authority or upon the income therefrom. The infrastructure revenue bonds and all interest and income thereon shall be exempt from all taxation by this state, or any county, municipality, political subdivision or agency thereof, except estate taxes.