Art....My wife, LaKeeta is a stained glass artist and so I had a heads up on that idea. I tried it and to be honest, the colored glass reduced the look of depth so I rejected the idea even though it was a great thought on my wife's part.
You will have a wealth of glass choices in your area. My Father and his brother were glaziers by trade and had a large Pittsburgh Paint and Glass shop. As a matter of fact, they had part of the contract on the John Hancock Center, Standard Oil Building, Harris Trust Bank, and a few others. I was around glass my entire life and thus exposed to all kinds of neat patterns, etc. The best for water is any version that is used as shower door glass. There is even a variety of glass patterns called "water glass". Don't get the tempered versions, just ask for the annealed (heat treated) type. It can be cut to order and it is not expensive at all as compared to the poured types used by many modelers. I would make the main part of my river out of glass and then use the Envirotex for the edges, etc. and blend making the shore look "wet". You will then also be able to mix in a little "garbage, limbs, tires", etc. that one would see along the shore of a typical river in a populated area. Some folks paint the bottom of the glass. I found that if you paint the surface upon which the glass is going to sit, it gives a little more depth. I used 1/8th inch masonite attached to a frame for the glass to sit on. For color, I would take a picture of the river that you want to model, and then take the photo to a paint shop and have them match the photo.
Hope this helps...
Alan