Another unexpected observation is how the water lilies thriving in my 3 fish ponds have struggled and not spread in my 2 "duck ponds" over the last decade. These shallow (<5 ft max) ponds were originally designed to be shallower wetlands, but were dug deeper based on DNR and FWS folks saying the ground would not hold water after taking soil core samples (have become more confident in my own judgement of the my land). A third emergent wetland in another field (about 3' max) has the same lilies spreading very well. One difference is that the lilies in the duck ponds may have greater muskrat pressure, but they just never look as robust in these ponds, even when muskrats are all trapped out. These duck ponds are almost exclusively fed by springs and could have water chemistry that the lilies don't like. Most of my other pond plants have done fine in these duck ponds though. Just wanted to share this observation.