Non-native grasses and eucalyptus trees brought to California centuries ago for agriculture and landscaping have reshaped the state’s fire dynamics.

Melted plastic pipes and drastic water-pressure drops are potentially leaching toxic chemicals and contaminants into local supplies. Multiple water authorities in north Los Angeles have issued Do Not Drink notices.

As hurricane-force winds fan the most destructive wildfires in California history across bone-dry foothills, communities face the dual threat of natural forces and a warming world.