As I understand it, all rain is mildly acidic when compared to naturally hard ground water. We notice that our pool pH changes after a rain. We’ve had the pool for nearly 30 years and it has always been this way.
I do think there's a chance that this acid rain is having a significant negative impact on flora and fawna over broad areas of land (especially in the Smokey Mountains). While I'm a self-professed "rabid conservative" I still think we're smart enough to generate energy without doing that type of broad ecological damage.