"This is not the current EPA website," a red banner on the page reads. "To navigate to the current EPA website, please go to www.epa.gov. This website is historical material reflecting the EPA website as it existed on January 19, 2017. This website is no longer updated and links to external websites and some internal pages may not work."
On the page you'll find information about the effects of acid rain, climate change (it exists!) and greenhouse gasses. Hell, there's even a press release about Fiat Chrysler violating the Clean Air Act. But, as Gizmodo notes, it's a mirror and can't host everything thanks to the limitations of it not being a full website. For images from AirNow, info regarding the Historic Air Technology Transfer Network, a database of press releases from the EPA or graphs from the Radiation Network, you'll have to navigate away from the site.
It doesn't differ too much from the official EPA website that's online now, but that could change in a heartbeat. Considering the current candidate to run the federal environmental watchdog agency, Scott Pruitt, is a vehement climate change denier, keeping this mirror site up and running could prove pretty valuable.
In his time as attorney general in Oklahoma, Pruitt sued the EPA more than a dozen times over the Clean Power Plan that curtails greenhouse gases, among other reasons. Pruitt's LinkedIn page describes him as "a leading advocate against the EPA's activist agenda."