When it shall appear upon an investigation by the state board of land commissioners that certain lands belonging to the state are more valuable for reservoir purposes than for any other purpose, the said board may withhold such lands from sale, and such lands shall be reserved by the state for storage purposes as a means of reclaiming other state lands in the vicinity. If, upon investigation, it is ascertained that certain state lands are more valuable for reservoir purposes than for any other purpose, and can be used as a means of reclaiming other lands in that vicinity, the said board may withhold the same from sale until such time as it is advisable to sell the same and may sell such lands as a whole for the purpose of reservoir site, and upon such terms and conditions as they may deem advisable, but no such lands shall be sold for less than ten dollars ($10.00) per acre: provided, that if the lands so sold for reservoir purposes are not used for the purpose of said reservoir, or if the works in connection with which said reservoir is to be used are not constructed within five (5) years from the granting or sale of the said lands, or such further time as the state land board shall grant, the rights granted shall revert to the state.