It has no legislative or judicial capacity, only executive, and to my knowledge, it has not erred. For example, we have all been the beneficiaries to the Clean Water Act, and its amendments and extensions.
Doesn't it basically have legislative capacity though? It makes decisions on what items can't be sold or manufactured. Regulating commerce is a legislative function, not an executive.
Their website explains the enforcement capacity, but under the Laws and Executive Orders menu it only mentions that it follows them. There is a long list of directives to the EPA, but they all come from the congress except for the three which were orders from Bill Clinton's office. (Those three have to do with federalism, recordkeeping, and dealing with Tribal governments.) Overall, it seems that any power the EPA has derives from the consent of those people governed. The people have the right to dismantle the EPA but I don't think it's a good idea.
She's pretty far out there, from what I've read. I'd hate to have to choose between a loon and an asshole. Unfortunately, that's almost always the choice in candidates that I have.