Irrigation and thermoelectric power for steam generation are the two largest users of fresh water in the United States. Irrigation accounts for 137 Bgpd and thermoelectric power 136 Bgpd.
Public supply plus domestic use from private wells accounts for 47 Bgpd. Industrial and mining use is about 21 Bgpd.
The numbers on a regional basis have more meaning as drought affects the traditional supplies of surface and aquifer water. Conservation measures in the public supply as well as alternative farming and irrigation methods are being applied and have been successful as the entire United States uses less water than it did 25 years ago. Even so, in some cases conservation measures are not enough. Where the supplies are not adequate to meet the demand, water rights are used to allocate diminishing supplies, but these can be disputed and often trigger lawsuits. The situation is not helped by inconsistent rulings by water districts.
In other parts of the world with large populations such as India and China the water resource and usage problems are even more acute.
USGS Water Use
For example, the water in the giant High Plains aquifer (also called Ogallala aquifer) covering a huge expanse from South Dakota to the Texas Panhandle was deposited during the ice age. Recharge is extremely slow, but the withdrawal rate is about 420 billion cubic feet per year, a volume equivalent to the annual flow of 18 Colorado Rivers. In eastern Colorado, much of the agricultural usage is for corn crops to support the new ethanol industry, but the Republican River and the underlying Ogallala aquifer are being depleted at a high rate that cannot sustain itself.
Fred Pearce in his classic book, When the River Run Dry, discusses another aspect of water…what economists call “virtual water”, the water that it takes to grow specific agricultural products. As we expend valuable water resources to grow and export crops, in effect we are exporting the water used to grow those crops. The United States exports a third of all the water it withdraws from the natural environment as virtual water…the water used to grow the grain for export and feed the beef for export. Recognition of the value of the water used to grow certain types of crops is receiving more attention as competition for supplies in arid and semi-arid areas heats up.
Supporters of a market based approach of allocation of water rights state that having the ability to sell or trade water rights would establish a true value for the water and encourage more efficiency in the system. Water in effect would go to the highest value uses, and discourage wasteful uses. Clear ownership of water rights would be established, thereby lessening the litigation over water rights that drag on in the courts.
The potential buyers of water supplies, including aquifers, are big cities in the arid southwest with money to spend. And with the increasing value of water, many owners do indeed sell their rights.
Opposing Websites Property and Environment Research Center World Bank Policy Research Initiative, Canada