249.800.  Revenue bonds may be issued without election, when, notice, procedure — election required, when. — The board of any district contemplating the issuance of revenue bonds under the provisions of sections 249.760 to 249.810 may give notice of its intention to issue the bonds without submitting the proposition to the voters of the district, the notice to state the maximum amount of bonds proposed to be issued and the general purpose of the bonds.  The notice shall further state the right of the voters in the district to file their written protest against the issuance of the bonds as hereinafter provided.  The notice shall be published twice in a newspaper published in the county in which the district is located.  If within fifteen days after the date of the first publication of the notice there shall not be filed with the secretary of the district a written protest against issuance of such revenue bonds, signed by a number equal to twenty-five percent of the voters voting at the last preceding election of supervisors within the sewer district, the board of the district shall have power to issue the revenue bonds of the district to the amount and for the purpose specified in the notice without an election.  If within fifteen days after the date of the first publication of the notice there is filed with the secretary of the district a written protest against the issuance of the revenue bonds signed by the requisite number of voters within the sewer district, the board of the district shall thereupon submit the proposed revenue bond issue to the voters of the district and, if a majority of the voters voting on the question shall vote in favor thereof, the proposed improvements may be made and the revenue bonds issued in payment of the cost thereof.