It is a nice graphic for a watermill building - and could replace the current watermill building in the RARR mod.
For ancient mines in my eyes the firaxis graphics with a wiped out waggon and the Vuldacon placement is the best solution. If indeed a good water connection to the watermill could be done, there would be the danger, that players could mix up that graphic with a real river tile on the map and think the water round the mill would provide an additional defense bonus for units by a river.