Ind. Code § 36-9-29.1-12
(k) An action to question the validity of any bonds issued for the flood control district or to prevent their issue must be brought before the date set for the sale of the bonds, and all bonds, from and after that date, are incontestable for any reason.
As added by Acts 1982, P.L.77, SEC.24. Amended by P.L.27-1986, SEC.7; P.L.6-1997, SEC.228.