Not exactly. Ocean water isn't usable without removing the salt and other solutes. When a lake or river dries up, it may lose its bedrock and therefore, even wh

Not exactly. Ocean water isn't usable without removing the salt and other solutes. When a lake or river dries up, it may lose its bedrock and therefore, even when it rains again, the river no longer holds water. So you end up with the water spread out over land, which is useless - because we don't have tree-like roots to just suck low density water out of the ground. We rely on large pools to be efficient.