As winter approaches, volunteers with Chizh for Cheii are preparing to deliver firewood to elders on the Navajo Nation reservation, where nearly 90% of homes rely on wood for heat.

The nonprofit organization, whose name means "firewood for Grandpa" in English, launched nine years ago. The volunteers work because they "don't want people to pass on because they were neglected," founder Loren Anthony said.

Young people and families traditionally help their elders collect and stockpile firewood, but when economic opportunity draws them away from the reservation, someone else has to step up.

"T...