What is the Risk of Expanding Groundwater Irrigation?

The demand for more food crops to feed a hungry world has expanded the need for irrigable lands.  Few want to risk the 1930s dust bowl or the droughts of the 1950s, especially with ongoing recurrent drought periods across much of North America on a regular basis.  The access to electricity and modern submersible pumps over the past 80 years has permitted a huge expansion in the amount of irrigation performed with groundwater.  Fly over the western United States and look for “crop-circles” where center wells act as the spoke for rotating irrigation systems.  They are obvious.  But virtually all of them are located in areas where surface water is not available and groundwater is the only source of water available for irrigation.  This might work where the groundwater is surficial, but if the groundwater were surficial and found in large quantities, wouldn’t there be surface waters that intercept the groundwater?  The groundwater would feed rivers, lakes and streams.  But in most places with center pivot irrigation, the groundwater is located well below the surface, and low rainfall means that recharge to these deeper aquifer systems is limited.

Irrigation use accounts for 40% of total water use in the United States.  USGS reports that in Arkansas and Nebraska, 90% of irrigation is groundwater.  These states are two largest groundwater users in the country.  California and Texas are right behind them in total use, with groundwater accounting for 80% of irrigation use.  Idaho, Oregon, South Dakota and Washington are among the states with irrigation accounting for in excess of 90%+ of total groundwater use, although their total use is much less than that of the other four states.  The areas irrigating with groundwater in all of these states competes directly with rural potable users, both individual and small cities, and with ecosystems that may support tourism, fishing, hunting and other outdoor activities.  Unfortunately USGS also reports that in all of these states, there are areas with severe declines in aquifer levels.  For example in South Dakota, USGS estimates that 70% of the water has been withdrawn in 30 years.  So the answer in 20 years will be……  There is no answer at the moment.  Some think we should just drill deeper, but this normally comes with added costs, assuming aquifers actually exist at these deeper levels.  But agriculture can’t afford to pay for treatment, meaning they it will be difficult for them participate in a solution.  Too few people in cities means alternative supplies like reclaimed water are not available.

The irrigation from deeper aquifer that do not recharge readily is indicative of a resource management paradigm that suggests we manage water supplies for a certain period of time (usually our lifetime or work period).  The consequences beyond that timeline are not considered because it is “beyond our lifetime” or planning periods, or we assume “someone will come up with something…”  Non-surficial groundwater supplies throughout the United States and probably the world should be viewed like a scratch-off lottery card.  Once in a while you have a winner, but it’s never enough to sustain you for the long-term, let alone pass it to your kids. And once it is spent, it’s gone.  Likewise once deeper aquifers are drained….  Bryan Fagan suggests most civilizations ultimately failed as a result of water woes.   If we want our civilization to survive well beyond our time, perhaps we should revisit history.

The long-term civilization model suggests we should consider a paradigm shift with respect to non-surficial groundwater.   Non-surficial groundwater is a resource that is finite – water that is stored, but once depleted, cannot be readily replaced.  That is not a sustainable solution and suggests that these types of groundwater sources should not be looked at as primary water supplies for irrigation, or for power or urban or domestic use for that matter – they should be considered back-up sources to protect us from surficial droughts that occur periodically.  The dust bowl impacts would have been lessened if we had back-up irrigation supplies from wells.  But in the future, if the aquifers are dry, and surficial droughts occur, the impact directly affects our food supplies and our economy.  We are often caught in defining the “long-term” as 20 years, but the US is 235 years old, but still considered young.  Our perspective of 20 years as long-term is only a quarter of a lifetime, which clearly falls short of long-term from the perspective of civilization.   Something to think about….