Did you mean the final lever on the grate in the water level? That unlocks the wall between the two forks. There's "soft walls" in there that lead you to the door that goes to the mine.
I believe the first level was the one that you just walk forwards to the door. Then in the second level you're in a hallway, where there is one room with tables and a blue item behind a gate. That the level were I'm stuck at.
Oh, that would be the fountain. To unlock that, you have to pull a lever in the Dining Hall. Then you can drink from it and banish the red skeleton blocking the exit door.
