Elpis' research suggests that the area around the Cleft is most likely inhabited by Apache and Hopi, rather than Navajo. I have therefore started making some plot adjustments:

The Navajo in the area are there because of La Casa's days as an Indian school run by the government. I have rewritten the WNDN interviews and will inject elsewhere that the Navajo are there because their children were "stolen" from their rez and placed in the school at La Casa. The parents followed in order to be close to the children even though no contact was permitted. In time a Navajo community formed.

Does that help?

Works for me!