Last week there was a local news article about the EPA fining three companies in the Inland NW. Two in Idaho, one in Spokane:
EPA fines Spokane Valley, Hayden companies for allegedly violating Clean Air ActAlligator performance has been one of the bigger diesel truck performance vendors. They moved to Idaho from Nevada back in 2013 or so.
Another similar company down near Boise completely shut down operations within the last 2 years. I don't know if the EPA came after them or what.