You're welcome
I think the National Park needs some more changes.
Why does it only remove the access to coal? Isn't Oil just as bad? Or Uranium?
I am not sure if it should remove the access to coal at all. Just because you have a National Park you are not forbidden to import coal, aren't you?
I think there are three options:
1) Make the Nationalpark only buildable if in the city the water and air pollution is lower than... uhm... no idea. Maybe 200 each? I am not sure how realistic that is. And remove the "removes access from coal" thing.
2) Make the Nationalpark remove the access from Coal, Oil, Uranium and any other ressources that goes in this direction. Maybe even Deer or Whale or Fisch etc because your city isn't allowed to hunt inside the National Park.
3) Let the city still have access to Coal but disable the ability to build highly pollutioning buildings like Coal Powerplant, Landfill, Garbage Dock etc.
However, I like the 1st option by far most. It would make sense that you build your Natinal Park in a city that's clean and not say: "Hmm... Our Water is almost undrinkable, our forstes die because of the acid rain, we barely can breath in that toxic smog all around here... We should definitly build a park here!"
It would also be cool if it places an "National Park" improvement on a random Forest (or maybe also Jungle/ Hill/ Peak/ Desert/ Savanna...?) like Manchu Piccu does. It would give -1 Food, -1 Production, +10 Commerce, +5 Health, -20 Air and -20 Water Pollution (for example).