Yeah, history actually supports that statement. You know how the Clean Air Act came out in like 1973 or so? Well the 50 years prior to that air pollution was steadily improving by natural market mechanisms. Government piggy-backed the movement and revisionist history leads us to believe we couldn't have done it without the state.
You think government protects the environment? Regulation hasn't stopped people from polluting. Government nukes. Regulation that forces BP to drill at a depth where they have little experience (though BP is at fault, too). Etc.
"According to Pentagon spokesman Kevin Doxey, in 1991 there were 17,400 contaminated toxic waste dumps at 1,850 U.S. government installations. Waste from these sites is leaking into groundwater, contaminating land, killing livestock, and causing increased rates of cancers."
If it were a corporation everyone would know about it and be calling for the end of capitalism. Erin Brockovich successfully sued for $300M and got an Oscar over pollution that didn't cause increased rates of cancer.
Liberty and the Environment: Freedom Protects, Government Destroys