Lake Mead, which sits behind Hoover Dam, is now on track to hit its lowest water level ever recorded and scientists blame a "mega drought" that they say is caused by climate change.
The country's largest reservoir is now at 37 percent of its capacity.
Pat Mulroy is the former head of the Southern Nevada Water Authority and she told CBS News this is a tipping point.
"This landscape screams problems to me. I mean, just look at the bathtub rings. To me that is an enormous wake up call," she says to CBS News.
The Feds could declare a water shortage for the lower Colorado River system later this summer which would force automatic water supply cuts to Nevada and Arizona next year.
If things get worse beyond that Southern California could feel a harsh impact.