Drought in the southwestern U.S. will deplete the vast Lake Mead this week to levels not seen since Hoover Dam was completed and the reservoir on the Colorado River was filled in the 1930s, federal water managers said Tuesday.
http://www.usatoday.com/...
The lake's previous record, broken this week, was in 1956 after another persistent drought. However, there is greater demand today. The population of Los Angeles City was less than 2.5 million in 1960 and is over 3.8 million today.
The problem: inflows continue to exceed outflows, with inflows 62% of what they were last year.
http://lakemead.water-data.com/
According to a 2013 Potsdam Institute for Climate Impact Research study:
...found that water resources will be affected by changes in rainfall and evaporation due to climate change, putting 40 percent more people at risk of absolute water scarcity.
Many Americans think water shortages only occur in third world distant lands; their faucet will always flow water on command. But in some areas of the US, reality may have a sobering lesson, and sooner than many expect.
Federal water managers gave Arizona and Nevada a 50-50 chance of seeing water deliveries cut in 2016.
Lake Mead is not the only body of water suffering historic declines.
The Ogallala Aquifer in the Mid-West received a lot of attention with the proposed route of the Keystone XL pipeline. Farmers worried, rightly so, that any oil spill would poison their primary source of water. But climate change is posing an even larger threat.
The once bounteous quantities of water that flowed under his farmland in the Texas Panhandle are a distant memory–pumped to the last drop. Now there is only one source of water for his wheat and sorghum: the sky above. “We try to catch anything that falls,” Spinhirne says.
The scope of this mounting crisis is difficult to overstate: The High Plains of Texas are swiftly running out of groundwater supplied by one of the world’s largest aquifers – the Ogallala. A study by Texas Tech University has predicted that if groundwater production goes unabated, vast portions of several counties in the southern High Plains will soon have little water left in the aquifer to be of any practical value.
http://www.nbcnews.com/...
Now, the Ogallala it is a closed system that has no real way to replenish itself from surface water. But as more irrigation water is drawn from the Ogallala due to reduced surface rainfall (climate change), the aquifer water levels continue to fall.
It can take as long as 6,000 years for water to percolate through the thick layers of earth and rock separating surface from aquifer. In most areas, pumping the water is akin to mining iron or copper; once removed from the ground, the resource doesn’t come back.
from the same article - fracking is contributing to the problem:
...the expansion of oil and gas drilling throughout the region, spurred by the advent of water-intensive hydraulic fracturing, has brought new challenges. The drilling process, which can use up millions of gallons of chemical-laced water per well, has stirred angst among some farmers. They worry about increased competition and the reality that fracked water can rarely be reused.
http://www.huffingtonpost.com/...
So the question is: what do we do when there is no water?