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Waiau-ua. This river could be utilised for the development of power by a dam built in any suitable site in the gorge below Hanmer Plains. Water could be taken out of the river just above the road-bridge, and the water-level raised by a dam 100 ft. high across the river, and a supplementary dam across the old river-channel. The drainage-area above this point is about 750 square miles. The river drains a length of about forty-seven miles of the main range, which varies in height from over 5,000 ft. to 7,100 ft. The conditions are favourable for a relatively high volume of flow. In the absence of data as to the flow of the river, the flow may be taken as equal to that of the Waimakariri per second per square mile, say a minimum flow of 1,600 cubic feet per second. The fall in the river from the roadbridge to the lower end of the gorge is 160 ft., the distance a little over seven miles. There is a fall of over 30 ft. in a short distance below the bridge. A dam 100 ft. high should in this short distance, or a little more, give about 20,000 b.h.p. at a cost of about £160,000 for the purely hydraulic works. By taking the water in a conduit to the lower end of the gorge, about seven miles in length, 30,000 b.h.p. would be got. Probably this would cost about twice as much per brake horse-power for the purely hydraulic part of the scheme. A gauging taken recently gave about 3,300 cubic feet per second for what was supposed to be a low-water level of the river, but the result seems high. It is possible the figures given for available power are low. It is not, perhaps, improbable that the Waiau-ua may have a high flow per second per squarejnile, in view of the great length of the main range drained by the river. Westland. The Chief Surveyor, Hokitika, has furnished a very complete report on the rivers of this provincial district. Some of the tributaries of the Grey River might be found suitable for power schemes, but detail information as to fall and flow are not yet available. The Arnold River, flowing from Lake Brunner, has a fall of about 234 ft. from the lake to its junction with the Grey River. The drainage-area feeding the lake is 178 square miles. The area of the lake is fifteen square miles. Measurements of ordinary flow of the river made by the Engineer of the Greymouth Harbour Board some years ago gave 1,750 cubic feet per second. This is nearly 10 cubic feet per second per square mile. The distance to Arnold bridge from the lake-outlet is 11J miles on the straight, and seventeen miles by the river. Allowing for fall in conduit, the limit of power to be got from the lake would be 22,000 b.h.p. if a nearly straight conduit were possible, but much less than this for a conduit following the river. A complete scheme would be a relatively costly one. It might be possible to get one or two smaller schemes river by dams and short races, but no information on this point is available. The Teremakau is a large river, but it flows in a wide shingle bed. It would therefore be difficult to take water out of it. Below Jackson's the fall is 20 ft. per mile, and this is too small to give any chance of a cheaply developable power scheme. Above Jackson's the fall is greater, but the riverbed is wide. A race to take a large volume of water would be expensive, and of considerable length to get a fair amount of power. Above the Otira, where the fall will be steeper, a conduit would require much tunnelling. The river is not a good one for power purposes. Power could probably be got easier from the Taipo River, a tributary of the Teremakau, than from that river itself. About four miles up from the main road there is a narrow chasm where a dam could be built and the water taken to a power-station on the main road. The minimum flow is given as 350 cubic feet per second, but the fall is not available. The Arahura River, if free from mining grants, would be a likely river to get some power schemes, and should be worthy of attention if a power scheme is investigated for the Hokitika-Greymouth district. Arthur's Pass (Otira and Rolleston). The possibilities of water-power in the Otira Gorge have a double interest, as the minor schemes may be developed for tunnel-construction, and the larger ones for an electric-traction scheme to work the railway traffic over the tunnel incline, and thus avoid all smoke nuisance in the long tunnel. For working air-drills, ventilation, haulage, &c, at the Otira end of the tunnel, the falls in Holt's Creek, Barrack Creek, and Westley's Creek are available. Each is probably good for 200- or 300-horse power, Holt's Creek being quite near the lower end of A 4 tunnel. At the Bealey end the Punch-bowl fall is available. A head of about 700 ft. is to be got by a little over half a mile of pipes. Ordinarilyseveral hundred horse-power would be got, perhaps five or six hundred, but in frost the amount would be reduced. For electric working of the railway traffic there are several schemes possible. To draw the full train-loads up the grade that could be brought up to Otira Station by the 84-ton locomotives contemplated to be used by the Railway Department in the future—without the steam locomotives —would require turbines of at least 1,600 b.h.p. For the existing B engines turbines of »bout 1,200 b.h.p. would be required.

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