Having seen it for myself, I can tell you that the oil companies really do bend over backwards to protect the environment, particularly in the sensitive Arctic.  The Exxon Valdez disaster especially was a wake-up call for vastly improved environmental standards.  In order to protect the tundra, drill sites are constructed on 4' thick gravel pads.  Even if a 1" drop of crude oil drips onto the pad, workers are required to shovel it up for proper disposal.  For any larger incidents that might occur, spill response teams are kept ready at a moment's notice, just like a fire department.  They are equipped to contain spills on land or sea.

Prudhoe Bay also enforces other environmental rules such as for wildlife protection.  If any wildlife is crossing the road, vehicles are required to either stop and wait, or to turn around and go another way.  Workers may not honk horns, race engines, yell, or in any way try to interfere with the natural movement of wildlife. They also may not feed anything to wildlife (though that's more of a safety issue.)

Actually, I've seen more wildlife in the Prudhoe Bay oilfield than anywhere else I've ever been. Some wildlife seen frequently in the Prudhoe Bay vicinity are: Arctic fox (which are quite curious and seen nearly every day), brown (grizzly) bears, caribou, and a variety of birds, such as ravens and geese. Other wildlife seen less frequently include polar bears, red fox, and musk oxen.