There are very few, if any, colleges that are stronger than Duke in public policy, environmental science, and environmental policy, especially at the undergrad level. (For full disclosure, I majored in Earth & Ocean Sciences at Duke, so I’m admittedly a bit biased.) Unfortunately, Duke is a reach for virtually everyone these days.
Although pub pol and environmental science majors are enrolled in the undergrad college of arts & sciences (Trinity), the undergraduate programs are housed in the schools of public policy (Sanford) and environmental science (Nicholas). Both are top-notch.
That said, I agree with the posters above that there many colleges that would provide perfectly good preparation for a career in environmental policy. Much depends on your stats and what you can afford.