Suppose there is an Earth-like world with magic. Someone (maybe wanting a mining city or an isolated power base), thousands of years ago, wanted to build a city on a certain desert mountain, five hundred miles inland and 2 miles above sea level, (This city is on a slope facing in the direction of the ocean. The mountain has sand or dirt--enough, at least, so that the surface is not too hard/rocky to be a barrier to plants growing.) So they had a wizard create a river - that is, a river that flows up vertically, (without the salt and other chemicals), then goes in a right angle, flowing through the air in a straight like till it runs into the mountain. At that point it flows downhill like a normal river.
What effects will the river have on the environment?