WAIKATO RIVER, LOWER LAKES
Visitors passing through the lower Waikato area seldom realise the presence of a number of lakes between Huntly and Rangiriri, for these can be seen only from vantage points away from the main thoroughfare. In order of size the lakes consist of Waikare, 13·2 sq. miles; Whangape, 4·5 sq. miles; Wahi or Waahi, 1·94 sq. miles; Rotongaro, 1·7 sq. miles; Kimihia, 1·05 sq. miles; and Hakanoa, Karaka, and Okowhao, all of which are less than 1 sq. mile in area.
These lakes are shallow, nowhere deeper than 15 ft and commonly less than 10 ft, and they owe their origin to one common cause – the deposition of sediments from the Waikato River which was more rapid than deposition in its tributaries. Thus it is that the lakes are distributed on either side of the Waikato River, that their water levels are close to river level, that they are separated from the river by low plains, and that the remainder of their coasts border hill country.
Much of Lake Kimihia has disappeared as the result of stopbanking during the opencast mining for coal from below the lake, followed by subsequent infilling. Lake Hakanoa is being developed as a playground within the Huntly borough and the rest serve as ponding areas during major floods of the Waikato River. As such, they are likely to remain until it is economic to develop their clay-rich sediments as farm land. This would require continual pumping of lake areas to the Waikato River and further protection against floods both locally and in areas down stream.
by James Cecil Schofield, M.SC., New Zealand Geological Survey, Otahuhu.