CVD lignite investigations in the vicinity of the proposed Lake Dunstan

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Thomson, R. 1978 CVD lignite investigations in the vicinity of the proposed Lake Dunstan. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 317 42 p.

Abstract: Reports produced in the period 1972-1975 on the environmental effects pf the Clutha dams essentially disregarded the possible adverse influence on the lignite preserved in the Cromwell basin. More recent reports and discussions prompted the CVD section of the MWD to investigate potential lignite deposits in areas of the Clutha Valley to be flooded by the proposed Lake Dunstan, and in which no definite evidence of lignite was already known. Four cored drill holes, totalling 696 metres, were located along the western margin of the arm of the proposed lake north of Cromwell. These complemented a hole previously drilled in the same area for a tentative damsite. A dozer cut was also located at the mouth of the Kawerau Gorge in the vicinity of a reported lignite mine. No lignite seams were penetrated int he drill holes. However, several seams were exposed int he dozer cut. It is concluded that lignite is probably absent inthe eastern part of the Clutha Valley upstream of a point 2 km north of Cromwell, and that future inundation near Cromwell and in the Kawarau arm of the lake will cause the irretrievable loss of only a small part of the estimated lignite reserves.