How farmers use water for irrigation and the quality of water that drains from farmland will be major topics of public and political discussion in 2016.  

This and next week’s articles rely heavily on researched hydrological data and reports obtained from professional scientists in agriculture and hydrology, articles in scientific journals, the USDA Economic Research Service (ERS) and the U.S. Geological Survey.  

There are two main issues: 1) is there enough water for everyone, and 2) is water runoff and water that has been used by agriculture, industry and households potable as it goes downstream to other consumers?  Today we look at the availability of water worldwide. 

Water Availability.  Most consumable water originates either from precipitation which is stored in reservoirs and upper soil formations or from underground aquifers.  Desalination projects account for less than one percent of the water consumed in the U.S., though as much as 40 percent of Israel’s water.

Even though El Nino is easing some of the immediate water shortages in parts of the Western U.S., U.S. Geological Survey reports quoted last month in USA Today indicate shrinking long-term supplies of water in the West and High Plains.  The Geological Survey conducted annual analyses of water levels in 32,000 sampled wells around the country over the past two decades. 

Water levels fell in 64 percent of the database wells over the past 20 years.  These wells mostly rely on underground aquifers throughout the country.  The losses are greatest in the seven westernmost “lower 48” states and the Ogalalla Aquifer, which underlies most of Nebraska and parts of six other High Plains states. 

Agricultural crop irrigation annually consumes around 90 percent of the water that is used for any purpose in the seven westernmost “lower 48” states.  Although some residents of the region have questioned if there is sufficient storage capacity for runoff of snow and rain and claim too much water ends up in the Pacific Ocean that could have been used more beneficially, state and federal government decision-makers have prevailed. 

Critics also argue that fishery, wetland and wildlife regulations require more runoff water than necessary, but government regulators have had the last word thus far.

Declining availability of water for agriculture, drinking and industrial use is a worldwide phenomenon.  A November National Public Radio (NPR) broadcast reported that a Saudi Arabian entrepreneur purchased 15 square miles of southern Arizona farmland recently–where both surface and underground water supplies are already short–to raise alfalfa hay to feed dairy cows in his home country. 

Each of 15 wells, one per square mile, supply the water needed for 10-11 alfalfa crops yearly, to produce hay for shipment to Saudi Arabia, where dairies and crops in this and nearby arid countries have mostly depleted their underground aquifers. 

NPR asked other Arizona farmers and other residents who were losing their diminishing subsurface and surface water for agricultural exports why they weren’t alarmed.  Many respondents said anyone has the right to farm and they didn’t know about the depletion of their aquifers. 

Hay isn’t the only crop that depletes U.S. underground water storages.  According to a December 2015 ERS report, in 2012 irrigated farms accounted for roughly half the total value of all U.S. crop sales.  Seventeen percent of U.S. cropland was irrigated in 2012; 90 percent of irrigated crops were produced in the 17 western-most states, excluding Alaska and Hawaii. 

U.S. agricultural exports overall doubled from 2006 to 2014, according to the same December 2015 ERS report.  China is the best customer for U.S. agricultural goods; Canada, Mexico and Japan are next. 

The large surplus of agricultural exports over imports of agricultural goods is a bright spot in the U.S. economy.  Agricultural production comes with costs however, mainly gradual lowering of the quantity and quality of water in the U.S.

Conclusions about water availability.  Currently, 89 percent of the world’s human population has access to potable water.  The supply of potable water available worldwide is declining, mostly because of depletion of underground supplies, even though the amounts of precipitation remain relatively constant. 

Agriculture is the main user of underground aquifers in the U.S., but 64 percent of the water used for irrigation comes from surface collectors like reservoirs and streams.  The amount of water available for agriculture and other uses from underground aquifers is declining more slowly in the U.S. than in many highly agricultural countries, largely because newer irrigation methods are reducing evaporation, which accounts for the loss of 42 percent of irrigated water.  Drought-tolerant crops are also being developed and planted.

India, China and many predominately desert countries are using up their underground aquifers much more rapidly.  Insufficiency of water will soon become a worldwide phenomenon, the United Nations Food and Agriculture Organization warns.

Next week’s Farm and Ranch Life column examines agricultural water runoff and related issues in greater depth. 


Dr. Rosmann is a farmer and Adjunct Professor in the Department of Occupational and Environmental Health at the University of Iowa.  Contact him at: www.agbehavioralhealth.com.