The "tool" cards as we called them were supposed to do similar things to what you mentioned. we cut them out for time purposes, though I'll admit they weren't as interesting as they sound.
I agree usually you feel like you'd like water to be optional instead of mandatory, though I think thats more the result of simplifying the water layout and raising the card value maximum, both of which butchered the original water mechanism lol. I like the sound of the compost bin! If we work on this further I'll give a try and see if discarding the highest cards isn't always obvious.
Thanks a lot for the suggestions!