No its correct that they have lack of access to water. But its important to note this is due to the negligence on the part of the Navajo nation, and not due to any misdeed of the USA.
As I showed, they have access to ground water and the government has a program in place to build wells. But their own government isnt carrying it out. So you should be outraged, but not at the USA, at the Navajo nation for not providing for their people when they could by not building enough wells or building up their infrastructure.