Andrew,
It was quite intentional. As I say in the nature photography book I'm writing: "A composition’s elements are, optimally, observed and informed decisions, and are, at their worst, haphazard mistakes."
There are probably more than ten square miles of where I could've chosen to set up this shot. I wandered quite a bit to find spots that lined up sets of pines nicely in the foreground (both for scale and for the point of interest), as possible locations. (I also chose this general area by map and compass, based on how I wanted the light and shadow, and came back to the spot at the peak moment, to get the shot.) Besides lining them up, I had to wait for the right moment, when the waterfall was falling the way I wanted. (It constantly wanders a little, based on gusts of wind.) Also, I had to wait for the right moment, when the spray was falling over a wide area.
By the way, the trees in the Sierras are also bigger than in the UK, so the scale might yet be even bigger than you think. They're also somewhat closer than the waterfall. Anyway, the upper falls (visible in this picture) is 1,430 feet high; the entire waterfall is 2,425 feet high.
(I've been sidetracked, but will get back to it.) It seems like real veils aren't that popular, right now. Anyway, here's a bridal veil shot from last year:
