Looks like great place. Did you use filter? Lens flare works nicely in some pictures but here I think it's bit distracting. I have older screwdrive version of 10-20mm sigma and it doesn't flare that "badly" naturally. Also what bothers me is the blacks, those seem to be way underexposed. I know it's difficult scene, but K-5 should be able to handle that, especially if multiple exposures are used. I would bet you used JPG, as RAW would give more room in lower end (and would also give opportunity to get some details out of shadows). Now blacks seem too black (no details/tones at all).
Composition could have also been better IMO as now the log cuts picture half in the first picture and it's bit hard to recognize the subject (is it the log, the waterfall, the rocks or the sun?). Second is better, I may have composed the biggest part of the waterfall in the golden ratio. The first one looks a bit "unbalanced" and "restless" in my eye. The second one looks bit "restless" (mostly because of underexposed blacks, distracting lens flare and bit weird greens) but overall is quite good.
But best of it all is that seems like you have found a great place. If possible, I suggest going there again and experimenting bit more. Different angles, maybe also different time of day if possible, trying to expose blacks bit better etc. Have fun. I am no pro, just a hobbyist and here are my 2 cents