Ok at the risk of a new guy being flamed I'll give my 2 cents ....
I don't dislike the EPA. I'm old enough to know what the pre-EPA industrial situation looked like. Local rivers could be lit on fire or turned interesting colors at times. Raw sewage pumped into rivers and lakes. Air choked with soot from coal plants. Heavy metals from various fuels being emitted unchecked. To me, the EPA was a needed force to bring things into some sort of responsible method for keeping clean air and water. I do consider myself an environmentalist, but then again I drive a truck that gets 14 mpg. It's a balance and the way I see it if we all try to some extent we don't have to be perfect.
Is there over-reach, or mismanagement? Yes, at times there is. I happen to agree with the general thoughts on this thread, that the dpf push has reduced efficiency and raised costs in a way that isn't correctly evaluated. Some of that overreach is the EPA, some is Congress and administrations directing the agency. It doesn't make it all bad, just in need of better leadership and some checks on power. Another glaring example is ethanol policy, it's not a good solution but was pushed so hard that it's here to stay.