We had a duck nesting last year in spring. And then she came back in summer.
At first worried about the mess, but she was actually quite good, hardly pooped into the pool. Only when she boys visiting (dad didn't hung around, but sometimes there were two or three of them) - and they always made a mighty mess.
But seeing the little ducklings was worth it. Build ramps di they can get out, which worked. Took them a while to learn to use it, but eventually they all got out, both times, and disappeared.