"NOCC" (Narrow Overflow Connecting Channel)

It appears (dependent on flows, of course) that there may be a narrow channel which splits off to the left from the left channel (about midway down the island) and connects across to the outflow channel from the hydro plant.
Being able to make it to this channel will be highly dependent upon flows, and will likely require ferrying across strong currents ... or ... you may have to carry up the larger island (or you may opt to paddle a up the outflow channel from the hydro plant, to beyond where this small channel connects, and then carry across the island there).