The Lake is blocked off by two cameramen looking to do a TV special until the player visits the Canalave Library.
Team Galactic uses a Galactic Bomb to dry up the lake. This explosion is felt in Canalave City, which is across the region. This leaves the lakebed mostly dry with a river exposed and puddles around. When the player arrives, they fights Team Galactic Commander Saturn but, Azelf is still captured.
After Team Galactic has been defeated at Mt. Coronet with the game's respective legendary Pokémon captured or defeated, the Lake will be rejuvenated with trees restored around the lake and all the water restored with the cavern at water level.