Crazy idea, but doesn't Colorado get like 300+ days of sun and even more intense in the mountain? If someone could come up with a nontoxic but long lasting black dye could you keep the water just above the freezing mark so that even a smaller solar system could keep up? Or maybe you could target a region of the shallows where you could put black tarps or something on the bottom? I wonder how much heat that sun could produce even in the winter at that altitude?