Mansergh, G.D. 1973 Geology of the Waimate county water supply intake, Otaio River, S118. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 160 7 p.
Abstract: Water is obtained from a filter gallery in Recent Alluvium in the Otaio River. The Recent Alluvium together with older alluvium deposits lies on a surface cut in Bluecliffs Silt and this surface slopes gently towards the left bank. Water losses from the river bed and the alluvial gravel through a fault 500 ft upstream of the intake, and the geological formation on its upstream side, may occur. The greatest groundwater flows should be close to the left bank in a shallow depression between the Bluecliffs Silt and the older gravel of the left bank. It is suggested that, either the filter gallery be shifted to the left bank, or a weir be built, founded on the Bluecliffs Silt, to raise the groundwater surface. (auth)