In all cases in which an assessment is levied upon land within the drainage district, and the assessment upon any tract is thereafter adjudged invalid by any court of competent jurisdiction, or, for any reason, the tract is not legally charged with the assessment, the tract shall be charged in any subsequent assessment with such proportion of the former assessment as the benefits derived by the land from the purposes for which the former assessment was levied bears to the whole amount of the former assessment.
(Added by Stats. 1943, Ch. 369.)