We have a small decorative pond - originally one of those plastic insets like you can buy at Lowe's, but it has developed a bit from there. It's pretty much a "water feature", though.
When we put it in, there were no small children on our block, so I really didn't worry about it. Then we got new neighbors next door who had a toddler, and dh and I talked about taking it out, but then the neighbors put in a similar pond, so we kept it, but we've made it fairly small child unfriendly. There's a low decorative fence around it, and we've planted wild roses all around it.
We do cover it with screen in the winter, but that's to keep the leaves out.