I'd like a little clarification on 'Alter River', specifically on the Divert River portion:
Q: what happens when the spell does not cover the whole river? Does the spell fail or is part of the river diverted?
Q: The 'banks' component ( This spell cannot cause a river to flow uphill, though the river surges over its natural banks and inundates terrain lower than its average depth ). What if the banks are cliffs a hundred feet above the river. Are those the banks? Or, again, does the spell fail?
Q: Within the banks part of the description, the line ends with "inundates terrain lower than its average depth". I presume that means the average depth of the river (that is, if the river is 10 feet deep, there is now a sudden wall of water ten feet high on the riverbank flowing away from the river).
Q: What happens to things flowing in the river? Do they go along the river's new course or do they wind up in the now-dry riverbank?
I think this spell could have been a lot clearer if the description made it sound like a long-lasting Dimension Door. Then the PC could have placed the outlet x number of feet from the center of where the river departed. I'd probably give it a medium range for that, but could be talked into long range. you would have to kick up the spell one or two levels in the process though.