I just checked,there are a few bad things I'dd like to point out:
-It's possible to save 75% using just one digger (one of the entrances releases lemmings twice as fast as the other 2).
-The water's active area overlaps the edges of the pit.
-There's one block I noticed to be offset by 1 pixel.
The design strongly remembers me to the level "the room with no exit" by the way
I'm not sure what other people will say,but at least the 1 digger solution backroute is something that really needs fixing