No contract, however, providing for the levy of such assessments shall be entered into with the state of Washington or the United States as above provided unless a proposition of entering into such a contract shall have first been submitted to the electors of the general improvement district or divisional district concerned, and by said electors approved.
[ 1927 c 254 § 56; RRS § 7402-56. Formerly RCW 89.24.560.]