Life from the Loam

You can't attempt to use a dredge ability if you don't have enough cards in your library.

Once you've announced that you're applying a card's dredge ability to replace a draw, players can't take any actions until you've put that card into your hand and milled cards.

If an effect puts a card into your hand without specifically using the word "draw," you're not drawing a card. Dredge can't replace this event.