Its a classic common resource problem: http://en.wikipedia.org/wiki/Tragedy_of_the_commons
"... individuals, acting independently and rationally according to each one's self-interest, behave contrary to the whole group's long-term best interests by depleting some common resource."

Historically, only 2 viable solutions exist:
1) An authority to regulate (% in this case)
2) Privatization

http://en.wikipedia.org/wiki/Tragedy_of_the_commons#Modern_solutions

Pick your poison..... but be quick about it.


Ref: "The Tragedy of the Commons". Science 162 (3859): 1243–1248. 1968. doi:10.1126/science.162.3859.1243