Approximate - nearest available gauge. Use as general reference only.
The photo above gives some perspective of the overall site/location of this feature. On this particular day, there was a lot of water going through the dams (on the other side of the island), so the river downstream was rather high, resulting in the N Wave not being very well formed. (I did not bother to suit up and surf.) As mentioned in the write-up, the wave will generally be at its best when there is less water being let out from the dams, making the river downstream a bit lower, meaning more 'drop' out of this pipe, and thus a bigger wave.