1913 The original Comox Lake impoundment dam was constructed at Comox Lake outlet by Wellington Colliery company [later Canadian Collieries (Dunsmuir) Ltd.].
The diversion facilities, as they existed in 1950 prior to redevelopment, were comprised of the present cross-stream weir with two electric gates that controlled flows into a half mile long open wooden flume. The flume led to a 1000 ft. section of brick lined “V” bottom canal – 26 ft. wide by 7 ft. deep in the center. A concrete spillway at the end of the canal diverted excess water back to the river through a short natural channel. Up to 300 cfs. of water for power production passed through a heavy trash rack, down this concrete forbay to a wood stave pipe 2.5 miles long to the power house where two 4700 H.P. reaction turbines generated 7 mw. of 25 cycle power.
This is a bit at odds with what I have seen so far…
Drawing records from the 1950’s show several alternative layouts for fish screens. In anticipation of fish screen construction the power intake section of the dam was constructed with four intakes, although only two were used for power generation. They converge immediately downstream of the dam into a single 3.66 m diameter woodstave penstock. The other two intakes were capped on the downstream side of the dam. Water velocity in the woodstave penstock is 2.64 m/s. The grade of the penstock for the first 1200 m is sufficient only to compensate for hydraulic losses in the pipe and maintain the hydraulic gradient 9.49 m above the crown of the pipe.