Riparian water law in Michigan has long been that "Reasonable Use" is restricted to use on the riparian property. It does not include the right, for example to pump water out of a lake to irrigate non riparian property. A farmer that sells off his/her lakefront property for housing has forever and irrevocably lost riparian rights and "reasonable use" is off the table. He/she can never irrigate from the lake again because once severed, riparian rights cannot be reassembled.
It would not surprise me, however, if Grant is right about an appeal being quite likely successful. Our ultra conservative Republican courts often ignore finders of fact and appropriate case and common law unless they fit their political persuasion. They often select and/or create laws to support their position, while claiming to be "strict constructionists." If they do select "reasonable use" as their standard in this case, they will be expanding the concept far beyond what has been done before and will be putting all of our lakes, streams, groundwater, and even the Great Lakes at risk.