law: The Dam Safety Act, 2021
  39. Compulsory evaluation in certain cases.-
  The comprehensive dam safety evaluation referred
  to in section 38 shall be compulsory in the case of, -
  (a) major modification to the original structure or design criteria;
  (b) discovery of an unusual condition at the dam or reservoir rim; and
  (c) an extreme hydrological or seismic event.