painting skills needed
Tom swears by the envortex, and has gotten good results with it. The biggest advantage of resins like this, is they are clear ( they can be tinted). with shallow water, poured clear, it can show bottom detail in a small stream. I have seen folks embed fish in the middle of several pours, so you could see fish in the stream. these resins are very thin, and will level out very nicely producing a very flat level surface, and that can be good or not so good, depending on the effect you are trying to get.
one disadvantage of epoxy resin approach is, due to the thinness of the resin, it can creep up the edges of things along the shore some due to surface tension. With this technique you detail your shoreline, and paint the surface your water will cover, to help get the depth effect you want, and make a dam where the water fronts an aisle,, test it to be sure there are no holes, and then pour in the epoxy resin.
What I don't like about this technique is it is a one shot deal. being prone to mistakes, I like multi step procedures , where I can correct or compensate for errors.
In any case, for deep waters, even if you use enviortex, you will have to paint the surface you will pour on to get the depth issues, using black or very dark blue to indicate deep water, and lightening shades of blue or green for shallower water.
I like painting up my water with acrylic paints, and using acrylic gloss medium to get the shine. that takes many coats. the advantage for me is in those many coats I have lots of chances to re work the colors, and help. a real disadvantage of my method os it dulls over time, and I have to add some more gloss medium every year or so to keep it looking wet. also, I have found that items, like a waterline model left on the river for a long time will stick, and this has damaged my river enough that I had to completely re do it using ployurathane floor finish instead of the gloss medium. this did not look quite as good, but the riverboat doesn't stick to it so it can be moved about.
Envotex dries very level and flat, so if left alone as it dries it will be a smooth as a mill pond. I have seen where folks worked with it and teased it as it dried to make waves or rough water, but again that is a one shot deal. I have also seen where folks used acrylic modeling compound on top of epoxy reins to get waves and other surface effects.