Tonight on Discovery – Killing the Colorado, a documentary about the drought facing large parts of the American West.
Seven states and over 40 million people all depend on the water from the Colorado River and the fact that there is not enough of it creates conflict over use.
The river itself flows from the Rocky Mountains to the Gulf of California, its 1,450 miles have supported human habitation for at least 8000 years.
Now this mighty river, which helped carve out the Grand Canyon, seldom reaches the sea. Instead the demands placed on it mean that most years it dries up some 100 miles before it gets to the ocean.
The big cities are often accused of drying up the valley but some reports say up to 75% is used for agriculture.
The drought facing the American West is predicted to be the worst in a 1,000 years.
Is water set to become the oil of the 21st century? What can be done?
This documentary by award winning filmmakers seeks to explore the roots of the problem, talks to the people using the water and looks at possible solutions.
Many experts say the impact from drought is only going to get worse, mirroring similar changes around the planet.
But others strike a note of optimism, saying the problems are caused by humans, therefore they can be fixed by humans.
Killing the Colorado premieres tonight at 9/8c on Discovery.