As I wrote here, I think of environmental issues in two categories:
- Regulation of pollution and emissions that affect other people's property. These regulations are essential to the maintenance of a system of strong private property rights. Without them, we would all be in court every day suing each other for damage to our property or water or air on our land from neighboring lands. Of course, we can all argue about whether set limits are reasonable, and we do.
- Regulations of land use that effects only your own land. This is a relatively new area of environmental law, ushered in by the Endangered Species act and various wetlands regulations. These regulations say that even if your proposed land use doesn't create any emissions that affect anyone else, the government may still ban your land use for some other environmentally related goal (habitat, watershed, anti-sprawl, the list is endless).
These land-use laws constitute by far the most distressing area to me in environmental law. In the worst cases, these laws can result in what are effectively 100% takings of a person's land without any compensation. (Example: you buy a lot on the ocean for $500,000 to build a beach house. Before you can build it, new regulations are passed making it illegal for you to build a house on that land. Yes, you still own the land, but it is now worthless to you since you cannot use or develop it). Good article on this here (pdf) and a listing of Cato Institute articles on this topic here.
The government is of necessity involved in #1, though we can argue that some regulatory structures are more efficient than others (e.g. trading vs. command and control). Government involvement in #2 is often a mess, and is one reason why private conservation groups and land trusts have made so much headway.
Reason has recently released a fairly comprehensive roundup of private conservation efforts that goes into much more detail on this topic.