No doubt animals are intelligent. (All life forms on Earth are equally 'intelligent'). No doubt they imagine a nice pool, then go about cutting down natural items like trees to use to make it.
However, they do not contemplate things like 'will cutting down the trees change the environment?'
Nor do they go mix limestone and gravel, and haul it to the river to make a better dam.
Niether did we a few hundred years ago but the dam got built.
Qibbling over structural materials aside, a dam is a dam.
The point is man's works are his natural works, same as beavers or bees.
We just do it better and with more vision because we are further up the food (intellect) chain.