Understanding the nexus between energy and water -water used for energy and energy used for water -has become increasing important in a changing world. As growing populations demand more energy supplies and water resources, research aims to analyze the interconnectedness of these two resources.Our study sought to quantify the energy-water relationship in Texas, specifically the relationship between electricity generation and water resources as it pertains to policy and society. We examined the water requirements for various types of electricity generating facilities, for typical systems both nationwide and in Texas. We also addressed the energy requirements of water supply and wastewater treatment systems, comparing national averages with Texas-specific values. Analysis of available data for Texas reveals that approximately 595,000 megaliters of water annually -enough water for over three million people for a year -are consumed by cooling the state's thermoelectric power plants while generating approximately 400 terawatt-hours of electricity. At the same time, each year Texas uses an estimated 2.1 to 2.7 terawatthours of electricity for water systems and 1.8 to 2.0 terawatt-hours for wastewater systems -enough electricity for about 100,000 people for a year. In preparing our analysis, it became clear that substantially more site-specific data are necessary for a full understanding of the nature of the energy-water nexus and the sustainability of economic growth in Texas. We recommend that Texas increase efforts to collect accurate data on the withdrawal and consumption of cooling and process water at power plants, as well as data on electricity consumption for public water supply and wastewater treatment plants and distribution systems. The overarching conclusion of our work is that increased efficiency advances the sustainable use of both energy and water. Improving water efficiency will reduce power demand, and improving energy efficiency will reduce water demand. Greater efficiency in usage of either energy or water will help stretch our finite supplies of both, as well as reduce costs to water and power consumers.

In Texas, groundwater and surface water are managed differently. Surface water is state-owned and governed by the doctrine of prior appropriation. Groundwater law is evolving and based upon a combination of court cases and legislative actions. Like soil, groundwater is property of the surface landowner. The 1904 East case confirmed the absolute ownership of water or the “rule of capture” for beneficial use, limited only in that malicious use or willful waste and, later, subsidence of adjoining properties were not permitted. The Texas Supreme Court later indicated that rule of capture might not be appropriate doctrine, but it declined to replace it with an alternative management doctrine. In the 1990s, there were two major legal changes to the existing legal regime. First, groundwater conservation districts were designated as the preferred method for groundwater management, further emphasizing local control. Second, protection of endangered species in Edwards Aquifer springs necessitated pumping restrictions. More recently, the Day case determined that landowners had a vested property right in water below their land prior to its capture, and the Bragg case determined that, in the facts of that case, the restricting of pumping of groundwater was a taking requiring compensation. Legal constraints will be an important factor in determining the future development of the Edwards Aquifer and associated water resources.

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