Limitations on Groundwater Use: Who Decides?

Groundwater provides an abundant water supply in many basins of the Americas – though undesired consequences may accompany its use.   Groundwater reservoirs can be classified in two simple ways:  those that are not stream-connected and receive little recharge; and, those that are stream-connected.   The non-stream connected basins hold a reservoir of water that has a finite life; using this water is a venture in mining.  Limitations relate to quantity of water in reserve, quality, ease of withdrawal, and ultimately, a decision as to over what timeframe one might decide to deplete the resource, leaving some or none to future generations.   Stream-connected basins, on the other hand, are limited by the extent to which a region permits impacts to the stream, whether there are transboundary controls, or pre-existing obligations to be met.   Historically, these questions have been addressed in the context of human uses:  the potential supply is quantified, the potential demand is assessed, and the resource is allocated to meet as many human needs, including urban, irrigation, and, sometimes, with reserves for potential future needs set aside.  Water allocation and water use in the United States over the past century presents paradigms that some developing countries might consider, as their water demands increase.  

Developing regions may want to study the paradigms of the United States, not as examples to follow; rather, as case studies in trade-offs and unintended consequences.  The United States has demonstrated shortcomings in many management approaches – particularly with respect to sustainability and impacts to ecological systems.  As regions of the United States struggle with issues of groundwater allocation, one reliable precept has emerged:  resolution of groundwater conflicts involves transfer of water from one sector to another, and often, transfers are associated with change to the hydrologic and ecologic landscape.   Choices can be informed by technical information, but there is seldom one best technical approach.  Often, choice on groundwater use is driven by economic conditions, absent consideration of limitations on growth or values regarding landscape or ecology.  Examples of water supply and groundwater use in the Southwestern United States are provided to illustrate some historic management procedures, unintended consequences, and impacts to watershed ecology.   The examples provide insight into the kinds of trade-offs that result when growth abuts against natural resource limitations.  Developing regions may conclude that, ultimately, those who have a stake in the hydrologic landscape may want a role in decision-making over groundwater resource development.