Includes bibliographical references (p. 41).; 14 figs; 10 tables

The report deals principally with the water resources in the catchment for which quantitative information is available, and hydrological data relating to these resources are presented. In describing the catchment, emphasis has been placed on those features affecting run-off. The distribution of average annual rainfall is examined. Details of daily, monthly and annual mean discharges from 1958 onwards at the principal gauging site at Rakaia Gorge bridge are given, together with flow duration curves derived therefrom. Reference is made to an earlier report on low flows in the Rakaia river. Flow data relating to discharges from Lake Coleridge and Highbank power stations, and from Lake Heron are included, together with some flow measurements made at other sites in the upper catchment The effect of intermittent discharges from Lake Coleridge power station on flow in the main river is discussed, and results given of an investigation into the reduction in river flow between Rakaia Gorge and State Highway No. 1 bridge. The average annual run-off is compared with the average annual rainfall. The distribution of ground water on the plain adjoining the main river is described. The uses made of water at present are summarised. Reference is made to possible future demands of water for irrigation, and to the views expressed by certain users on future large abstractions. Details of water quality analysis are also included. (auth.)

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