153.87 Mortgage or sale by board of district property prohibited; rights of bondholders protected.—No district board shall have power to mortgage, pledge, encumber, sell or otherwise convey all or any part of any water system or sewer system, or both, except that the district board may dispose of any part of such system or systems as may be no longer necessary for the purposes of the district. The provisions of this section shall be deemed to constitute a contract with all bondholders. All district property shall be exempt from levy and sale by virtue of an execution and no execution or other judicial process shall issue against such property nor shall any judgment against a district be a charge or lien on its property or revenues; provided, that nothing herein contained shall apply to or limit the rights of bondholders to pursue any remedy for the enforcement of any lien or pledge given by a district on revenues derived from the operation of any water system or sewer system, or both.
