The water revenue bonds authorized by this 1959 act N.M. Stat. Ann. § 72-4-2 to 72-4-12 and the income from the water revenue bonds, all mortgages or other security instrument executed as security for the water revenue bonds, all agreements made pursuant to the provisions hereof and revenue derived therefrom by the county shall be exempt from all taxation by the state of New Mexico, or any subdivision thereof.