I went on a tour of the North Slope drilling sites about 12 years ago. It was with a group of staffers from Republican offices. I worked for a Denocratic state senator so I don't know why I was included. I do know the language from our tour guide was a lot different on this tour than it was on another tour a friend took. That on was was meant for Democrats. Those people know their audience. I heard a lot about burdensome regulations and what was going to happen "When Anwar comes on line."
The point is regulations in effect now may be changed when people who regard them as burdensome have been in power a little longer. Pumping the oil is all that matters to many.
And I know of unreported or underreported spills which have already happened. In the meantime damage from the Exxon Valdez spill continues.
Anytime oil is pumped from the ground and transported there will be risk of spills and other damage.
The only reason we are so eager to open the wildlife refuge is that we are unwilling to change our wasteful ways. The US already uses a huge and disporportionate share of the world's energy. There is a finite supply of oil and generations to come who might need it.
A few simple measures implemented now would save more oil in a few years than ANWR will produce. We all know them; reduce speed, make sure tires are properly inflated, car pool, walk, ride bikes, stay home, quit driving large heavy vehicles. (Driving from my home about 40 miles outside Anchorage, I always see truck after truck, after SUV, after Hummer with one person in each. At least we are in a fuel-efficient 5-year-old Toyota Corolla.)