5.7 km standby tunnel to carry 55 m3/sec from diversion weir on Matsuko river when water is available. Joint venture of Hochtief, Concor and Impregilo known as Matsoku Civil Contractors with consultants Matsoku Diversion Partnership comprising Consult 4 in joint venture with Lescon/FMA. Access adit 190 m long completed and work proceeding on 5 m-high, 4.5 m-wide horseshoe-shaped main tunnel being driven straight on 1:230 downgrade using drill/blast in basaltic formations. Crown will be sprayed with fibre-reinforced shotcrete and invert will have concrete channel. Advances of 25 m to 30 m/week being achieved. March 1999.