Graham, I guess your being born in 1956 made you very aware of the powerplant collapse on the American side as you grew up. That must have been a sight to see from the Canadian side and a terror to those working at the powerplant. The fact that only one person died is amazing.
I too like the features of the canals running from the intake to the powerplant and the reservoir lake for catching additional flow at night. I would have loved to tour that facility before it was shut down. Even now it must be a thrill to imagine what it was like.
Absolutely Jinman, in fact, a sharp-eyed observer, when looking from the Cdn. side at the gorge wall on the US side, just down-stream of the Rainbow Bridge you can still see a bit of the remains of the collapsed Schoellkopf GS. A near vertical stone wall is visible which stood behind plant 1, and to the right of that, at the waterline you can see the tailraces of the collapsed plant 2. The generators and everything else is still buried under all that rubble, which is now growing trees on it. The massive Robert Moses plant at Lewiston replaced it.
As you mentioned, both the Moses and Adam Beck GS employ holding reservoirs with pump-generating stations to draw extra water off-peak (at night) to fill the reservoirs, then during the day with the extra demand, the water is released and the energy is re-captured without increasing amount of water diverted from going over the falls. There is a US-Canada treaty that limits the amount of water that can be diverted from the upper river to ensure an adequate flow over the falls for tourism.
If you think about it, these reservoirs are an evolution of the surge tanks used in the old OPGS plant. Someone must have thought, "Hey, why can't we utilize this excess water that is collected to generate more power."
Would have been cool to tour these old facilities. Unfortunately none of the Canadian plants were open to tours. The US side Robert Moses plant is though. When I was much younger, me and some friends tried to get into the old Toronto Power GS after it closed - around '73. We got into the forebay hall but were kind of freaked out by the place, it is actually pretty scary inside. Anyway, we left and now even the windows are sealed up and it is fenced off. There is talk of making one of them, TP or Rankine plant (the other plant that is visible above the falls into a museum.
Jinman, if you REALLY want to be amazed by the "underground" world at Niagara, you have to check out this link. It is AWESOME.
the Vanishing Point
Specifically, check out the 3 Niagara plants:
Ontario Power Company Hydroelectric Plant
Toronto Power Company Hydroelectric Plant
William Birch Rankine Power Station
The latter two were above the falls and had deep wheelpits excavated under them where water fell through penstocks to the turbines at the bottom. Long vertical driveshafts drove the generators which were at ground level. The outflow exited through a tunnel bored from the base of the wheelpit to behind the falls.
The Toronto Power tunnel portal is hidden behind the curtain of water flowing over the Horseshoe Falls but the Rankine portal is visible (looks like a train tunnel) between the Ontario Power GS building and the Scenic Tunnel observation platform. You can see it better from the US side or the Maid of the Mist. A similar tunnel portal on the US side exists which handled the outflow from the Edward Dean Adams plant. I remember as a kid wondering where this high-speed water shooting out from these tunnels was coming from. Now there is barely a trickle, mostly from ground water seepage.