This act shall not be construed as repealing any law now in force in this state, and shall apply only to drainage districts organized hereunder and hereafter: Provided, only, That Kan. Stat. Ann. §§ 24-602 and 24-611 may be made applicable to and become a part of the general drainage laws existing in 1909, whenever a petition of two-fifths of the voters in said districts shall be presented to the board of county commissioners, praying therefor in any county in which there has been organized a drainage district under existing laws at the time of the taking effect of this act.