Where the annexation of territory to a district would otherwise be valid, except that such annexed territory was not within the boundaries of a municipal utility district organized and existing under Chapter 218 of the Statutes of 1921, or the Municipal Utility District Act, such annexation shall be valid. This section shall be applied retroactively to validate the annexation of such territory to a district as of the date that the annexation would otherwise have been valid.
Ca. Pub. Res. Code § 5572.1