We have quite a few mills with waterwheels and also waterwheels as separate PNG objects in our free Vintyri™ Cartographic Collections. You'll find the mills in Symbol Set 3, Commercial and Artisans Structures. The waterwheels are in Symbol Set 2, Base Structures, Parts and Externals. There also are parts to put together the water chutes necessary for top-driven waterwheels. The symbols are based on real historical buildings. Photos of most of the originals are in the accompanying PDFs. These symbols are free, open gaming material that can be used in personal, commercial and other work at no cost. Go to: http://www.vintyri.org