The water in the Hover Dam comes from the Colorado River, which flows through the western United States.
Extreme weather conditions have caused the river's water level to be record low.
It affects both the amount of drinking water and electricity production in the area.
In Las Vegas, water restrictions have been imposed and a state of emergency has been declared for the next few months.
Affects thousands
The US Department of Water Management has determined that there is a shortage of water in the Colorado River.
The levels are the lowest that have been measured, but their calculations show that the situation is expected to get even worse.
- Farmers are forced to set aside their fields due to reduced water allocation, says Christian Geralch, environmental activist at the organization Sierra Club.
Follow SVT's correspondent Stefan Åsberg to Hooverdammen and Las Vegas in the clip above.