Compensation in cases of ascertainable substantial damage.

20. Compensation may be awarded in respect of any substantial damage caused by the exercise of any of the powers conferred by or under this Act, which is capable of being ascertained and estimated at the time of awarding such compensation:

Provided that no compensation shall be awarded in respect of any damage arising from -

1. (a) deterioration of climate, or
2. (b) stoppage of navigation, or the means of rafting timber or of watering cattle, or
3. (c) stoppage or diminution of any supply of water in consequence of the exercise of the power conferred by section 4, if no use has been made of such supply within the five years prior to the date of issue of the notification under section 4, or
4. (d) failure or stoppage of the water in a canal, when such failure or stoppage is due to-
   • (i) any cause beyond the control of the State Government,
   • (ii) the