Well, it was the third level I made, and all of my solutions left you with only a few seconds left, but I can see of course that much more is possible. Still, if you're not thinking, the time will run out before you know it!
@JM: The reason for this is that if the water level were higher, it would become a precision thing with where to stop digging and where to start building. Since this was annoying, I lowered the water level, even though it is technically inactive now.