Two glasses of tap water from two different cities aren't the same water. Source rock, disinfectant choice, and plumbing all leave a taste behind.

A 1996 law lets Congress erase agency rules with a simple vote, and this month it's aimed squarely at California's authority to write its own tailpipe standards.

The EPA transmitted four California vehicle and equipment emission waivers to Congress on Friday, arguing they qualify for fast-track repeal under the Congressional Review Act.