Immediately upon the withdrawal of any land for the state by the department of the interior, and the inauguration of work by the contractor, it shall be the duty of the director of the department of water resources, by publication once each week in some newspaper of the county in which said lands are situated, and one (1) newspaper at the state capital, for a period of four (4) weeks, to give notice that said land, or any part thereof as the director in his discretion may deem is for the best interests of the state, is open for settlement, the price for which said land will be sold to settlers by the state and the contract price at which settlers can purchase water rights or shares in such works provided, however, that in said notice two (2) dates of opening shall be stated, the first of which shall be at least thirty (30) days prior to the second. Said notice shall state that at the first opening only ex-service persons may participate in the entry and selection of land, and that on the day of opening all those present will be allowed to make a selection by lot, the method of drawing by lot to be determined by the director of the department of water resources; and that said notice shall state that due proof that they are ex-service persons, will be required of all applicants for the entry and selection of land at the first opening, and shall state what proof will be required.