I have spent a bit of time over the years on the Tongario river, it's normally a winter fishery, July, aug is when the trout run,
But I have fished it several times in summer, it's a nice blue ribbon river, in peak NZ summer, have caught a few nice brown trout, 7-9 lbs at that time, but no bigger rainbows,
Other rivers in the region, that offer a more wilderness experience, are more to my likening.
Hope that fish graced the table, as skin damage, and warm river temps, much less chance of surviving.
Hope you enjoy the area, central North island NZ, is a great outdoor playground.