LAKE ROTOMAHANA.

New Zealand Herald, Volume LXVII, Issue 20760, 31 December 1930, Page 14

LAKE ROTOMAHANA.

Sir,—On December 8 I visited Rotomahana Lake with Mr. Warbrick and spent some time viewing the height of lako and the country between it and Lake Tarawera. Rotomahana has fallen 2ft. since I was there a year ago. This was due to no continual rain for several days at a time during the winter months, but the greatest recorded, rise in the lake during the last four or five years was 25ft. in six weeks —about 19ft. rise would cause the lake to overflow and will greatly increase the speed at which it will empty itself into Tarawera, because the incline toward Tarawera would be.steep, whereas if opened now by making a cutting of 19ft. deep by 30t3yds. or so long there would bo some distance of level ground beforo the water reached a steep toward Tarawera. It would not be costly and could be done by some of the unemployed whom tho Government are trying to find work for. Twenty men for six or eighl weeks should make a big hole in the job. But there is nothing more sure than the fact that the dam will overflow and burst the" dam whenever there are a few days of continuous heavy rain. Rerewhakaitu, which I also visited, has gone down two or three feet, but heavy rains would quickly it again—there is a long arm of the |iake at the north-west side which runs toward Rotomahana. It would require a rise (at the end of this arm) of 20ft. before the lake would overflow into Rotomahana. Not far from Mr. Brett's house the end of a fence can be seen quite 15ft. below the water, showing the lake had risen considerably, although, like Rotomahana, it had fallen 2ft. or more during the winter and spring. I did not examine l the contours of the hills to the east and cannot say whether, when it overflows, it will be toward Rotomahana Lake or Rangitikei River, but an earthquake at any time (and there were three at Rotorua last week) might make a crack or fracture of the land between Rotomahana and Tarawera, which would quickly develop into a burst dam. This also applies to Rerewhakaitu. C. A. WniTNEV.