Sleeper, your first two prototype pics have a look I’m familiar with from climbing, another hobby. They are quite different from the picture of the Colorado River in Nevada posted later.
There, the blue color is a reflection from the sky. In your case, those pics look just like many of the glacial runoff streams I’ve see. The water itself, and perhaps the streambed, may well be the source of the pale blue color in your prototype pics.
In a real river, the perceived color is mostly a product of three variables, the color of the bed, the color of the water itself, and the nature, depth, and color of the reflections the sky imparts to the surface. In my OPINION, you might be able to match an effect by using a different variable, example, if you matched the look of the bed by changing how your layout water reflected light, or if you matched a water color by painting the bed, BUT, if you do, you are likely to see unintended effects when you move from place to place and change viewing angle. In my opinion, you will be best served matching the bed to the prototype, the water tint to the prototype, then use reflection to fine tune it.
A glacier grinds up a LOT of rock as it moves, and the runoff water contains a high degree of rock fragments, known as “glacial flour”. Drinking that stuff is reported to be very bad news, and I’ve never done it. Drinking straight glacial melt, without the flour, is a problem too, as it has zero minerals and will leach critical minerals out of your system.
Anyway, if your stream is glacier fed, and you are sure you want to model a river that is going to look pretty strange, even though the prototype looks just as strange, even when you’re standing beside it, then I think the color in the stream bed in your second layout pic, (not sure what the darker blues beside the streambed are but they don’t match the prototype pics) is right where you want to be.
Envirotex, melted hobby-water beads,