IS GROUNDWATER USE A CASE OF THE TRAGEDY OF THE COMMONS? By Courtney Wilson CIVE 633 ENVIRONMENTAL HYDROLOGY Fall 2009 October 28, 2009 Potable water makes up approximately 0.8% of all water on Earth and the majority of the water available for consumption is in the form of groundwater. Humans rely on groundwater for consumption, irrigation and industrial purposes. A growing concern is that groundwater consumption often goes unregulated. When overconsumption of groundwater begins affecting surface water the relationship between the two becomes apparent. Precipitation over land appears in two forms: surface water and groundwater; however the two are frequently treated as if they come from two different sources. Surface water use is effectively regulated and groundwater use is still often unregulated. Will lack of understanding and lack of regulation lead groundwater to become a modern day “Tragedy of the Commons”? When groundwater is pumped at a rate greater then it is replenished the water table is lowered. If the water table is lowered below the well depth the well will need to be deepened, and pumping cost will increase because the water will have to be extracted from a lower elevation. Water extracted from deeper levels will tend to be more saline. Over pumping groundwater by an individual will lead to lowering the water table, increased pumping cost, and deterioration of water quality. Ultimately, the cost for an individual overuse of the resource is shared by all, leading to the Tragedy of the Commons. Historically, groundwater rights have been governed using either the Law of Prior Appropriation or the Rule of Absolute Ownership (Law of Capture). The Law of Prior Appropriation was originally developed to determine ownership of surface water in California during the gold rush. When applied to groundwater, the Law of Prior Appropriation allows the individual who initially used the water for beneficial use to have rights to that water. Beneficial use it typically defined as use for irrigation, industrial or domestic use. According to the Law of Capture, a landowner is entitled to the ground water under his land. The problem with the Law of Capture is that underground aquifers frequently span multiple land owners. One land owner’s groundwater pumping can affect the surrounding landowners by drawing down the water table. Also, groundwater is not an unlimited resource. Groundwater is replenished over a much longer period of time, where surface water is replaced a lot faster. Reliance on the Law of Prior Appropriation and the Law of Capture will unfortunately lead to the Tragedy of the Commons. The Tragedy of the Commons teaches us that with each individual acting logically in her/his best interest, the commons will be destroyed to the detriment of all. The cost of over pumping groundwater is not immediately seen and is shared by all users with access to the aquifer, while the benefits are gained immediately and solely by the user. With each person making rational economic decisions about how much ground water they need and how to put the groundwater to beneficial use, this common resource will be destroyed. Modern day ground water regulation in California involves multiple water districts acting independently in the best interest of their populations. This state of affairs has lead to water mining throughout California. While we typically think of the Tragedy of the Commons involving individuals acting in their best, the actions of the independent water districts are a wonderful modern day example of the Tragedy of the Commons. Each water district acts in its own best interest without regard for the other districts or the water source. Continuing this behavior will lead to depleted groundwater supplies and the ultimate demise of all. Whether it is individuals acting to benefit themselves or water agencies acting without concern for neighboring agencies, one can see how groundwater use is a case for the Tragedy of the Commons. Because the cost of over pumping groundwater is divided among all users, it is not in the best interest of an individual to reduce his/her consumption. The incremental net gain of one user is far greater than the incurred cost. The perception that cost of over pumping groundwater is seemingly minimal compared to the benefits gained will invariably lead to the Tragedy of the Commons. References Ashley, J., and Z. Smith. Groundwater Management in the West. Univerisity of Nebraska Press, 1999. Glennon, Robert. Water Follies: Groundwater Pumping and the Fate of America's Freshwaters. Island Press, 2002. US Geological Survey. Ground-Water Depletion. http://ga.water.usgs.gov

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