CHAPTER 7 WATER CONFLICTS FROM THE VIEWPOINT OF A REGULATOR

• Jurisdiction: United States

Geothermal Resources Development
(Jan 1977)
CHAPTER 7
WATER CONFLICTS FROM THE VIEWPOINT OF A REGULATOR
Dee C. Hansen
State Engineer
Salt Lake City, Utah

INTRODUCTION

Within the past several years, the potential and feasibility of developing geothermal resources for power generation and other uses has become more and more apparent. Most of the interest in developing geothermal resources is in the 13 Western States and 2 Gulf Coast States. Nearly all of the Western States have adopted legislation to control geothermal development¹ and have vested the authority to administer it with either their oil and gas or mineral resources agency, or their water rights agency, depending on whether the resource was defined within the state as a mineral or water resource. However, regardless of how the geothermal resource is defined or regulated within a state, the fact remains that water in the medium by which the heat energy is conveyed in a geothermal system and the interrelationship between the geothermal system and other hydrologic systems needs to be examined.

During the early period of geothermal development it was believed that all thermal waters were of magmatic origin, but in recent years this concept has been one of controversy and now it is generally believed that most thermal waters are of meteoric origin² (being recharged from the surface precipitation). If thermal waters are indeed meteoric in origin, then the problem of perhaps increasing the natural recharge to the geothermal reservoir as large quantities of geothermal fluids are withdrawn is a concern to other water users in the area. Also, in several locations in the West, thermal waters have occurred on the surface as seeps and springs and are presently being used for recreation and therapeutic purposes, space heating and agricultural uses, such as greenhouses, fish farming, irrigation, and stockwatering. Many of these uses of thermal waters have been established under state water laws and, therefore, it is the state's responsibility to protect them.

POTENTIAL OF GEOTHERMAL IN THE WEST

The Western United States appears to have the greatest potential for geothermal development in the United States.³ Figures 1 and 2 are maps of the Western States showing the known geothermal resources areas (KGRA) and areas considered prospectively valuable for geothermal development. The Geysers field in California is currently the only place in the United States where electricity is produced commercially from geothermal sources. The present generating capacity at the Geysers is 500 mw.⁴ There are also numerous other places in the West where thermal waters are used for nonelectric purposes such as irrigation, industrial, space heating, and recreational uses.

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Figure 1. Map of the states of California, Nevada, Oregon, and Washington showing lands classified for geothermal resources (Source — Goodwin, et al., "Classification of Public Lands")

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Figure 2. Map of the states of Arizona, Colorado, Montana, New Mexico, Idaho, Wyoming, and Utah showing lands classified for geothermal resources (Source — Goodwin, et al., "Classification of Public Lands")

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Geothermal reservoirs can be divided into three basic types, (1) hydrothermal systems, (2) geopressured systems, and (3) hot dry rock systems. The hydrothermal systems can be divided into three subgroups; (1) dry steam systems in which only steam is produced, (2) wet steam systems in which both steam and hot water are produced, and (3) the hot water systems in which water is produced having a temperature below the boiling point. The dry steam systems are quite uncommon and only three have been developed in the world of which the Geysers in California is one. The wet steam systems are characterized by hot springs and fumaroles and this type of system will possibly be the main type developed...