Well, as the only water nation left in the game, the pool is Ryleh's to pee in or not as we see fit.
As for S9 casters, I understand that they are not always necessary to cast Armageddon. Our thaumaturges speculate that if a casting of Solar Brilliance was to become corrupted, perhaps by long exposure to vast clouds of poison and stench, that the very solar sphere might be damaged or disrupted, causing all manner of dire portents upon the world.