THe word you’re looking for is “conservationist.” An environmentalist doesn’t want us to use the resources God gave us while the conservationist wisely uses all the God given resources. Key word is wisely.
I once had to school a conservative US Senator on national radio about that when he said “We’re all environmentalists.”
That said, I also support the new rule. Hikers should carry copious amounts of water in the Grand Canyon, not just a 12 oz throw away bottle. Nalgene’s run about $10 each so people tend to hang on to them. A friend of mine told me that he came across some guy who was several miles into the trail and his can of Coke was empty. My friend had enough water on him that he was able to spare an entire gallon to give the guy.
Try coming up from the bottom after descending the North trail, ASSUMING that the water supply is WORKING at IG, 3 and 1.5 mile rest stops!