Madeline Heim gets enthused talking about wetlands or watersheds. Her voice picks up a tone of wonder at the mention of "dark skies." And it carries a bit of an edge on the subject of climate change.

MINNESOTA CITY, Minn. – Sabrina Chandler spent much of her life on the other end of the Mississippi River. Growing up on the Gulf Coast near New Orleans, where levees wall the river off, she had to ...