Be aware there are two trees in the gorge section of the Nith. Fist one is in the middle of the river some 20 -30 yards down stream of the "pour-over" at the line of boulders on the exit. It's an old tree, fairly bare and pointing downstream but easily paddled around, however swimmers should be aware that it is there. The second is against the river bank another few yards down stream on river left, so be careful where you swim to if you're in the water.
Pretty sure the next big water will move them further down stream.