President Donald Trump is obsessed with how California manages its water supply, demanding changes as one price of giving the state billions of dollars in aid to cope with Southern California’s deadly and destructive wildfires. However, Trump’s specific complaints are not grounded in hydrologic or managerial reality — such as his insistence that a lack of water from Northern California was a factor in either the fires’ eruption or the firefighting efforts. Hydrants dried up largely because systems were designed to deal with individual structure fires, not widespread wildfires involving thousands of buildings.