TL;DR
Blueprints should make ghost on water, so it's easier to know where to landfill.What ?
When player pastes blueprint, it doesn't leave a ghost on water. This makes it hard to guess, where landfill should go to satisfy blueprint requirements. Pasting blueprint covering water should automatically place landfill, similarly as it can now remove trees or stones.Why ?
Players want to have accurate placement on the water, because of aesthetic reasons or they need accurate land/water border for water pump placement.One workaround is to go to use creative mod, make a lake, fill it with landfill and paste blueprint there. Then make a new blueprint, so it contains landfill. Then it can be used in game again. Suggestion will improve user experience.