+1 on willow. There are a lot of willow species, but I'd say that is one of the more bushy kind. If so, it will not get real tall (or suck up a lot of water), but rather bush-like in appearance. It does not appear to be near the dam so "take it or leave it". Are there other willows near by? One more thing to consider is that one willow will make a lot more willows every year. I personally like willow trees so long as they are where I want them. My pond is not necessarily where I would want them.

An interesting fact about willows is that you can make willow tea (or willow water) which helps root growth on newly started tree cuttings. If you are into propagating trees from their branches or just want to stimulate root growth on your potted plants, dice up the new years growth from the branches, make some willow tea and water your trees/plants with the water. The tea actually smells good, but I can't get myself to take a slug for fear of a case of the urgencies.

Fish on!,
Noel