and therapeutic reasons and is still popular today. Historical use of hydrothermal basins was mostly confined to hot springs, due in part to the great abundance of hot springs relative to the very few geyser basins worldwide. More importantly, historical use of thermal features was limited to those found at Earth’s surface. It was not until the Industrial Revolution in the nine- teenth century that technological development and increas- ing demand for electricity inspired a new use for geothermal resources: energy production.
Geothermal Energy Development
Even though geothermal energy comprises less than 1% of total global energy production and only 4% of total renew- able energy use (IEA 2007), geothermal energy prospecting and development has had a greater impact on geyser basins worldwide than any other human activity. Globally, at least eight geyser basins have lost all or most of their natural geyser activity due to geothermal energy development (Bryan 1995), while several others are threatened by potential development from geothermal leases on site or in adjacent areas. Because of the lack of long-term documentation of geysers in many loca- tions, the exact number of individual features that have been altered or destroyed is uncertain.
Damage to geysers and springs from geothermal energy development results from drilling into the subsurface hydro- thermal reservoir. Drill holes created to extract heated
Geysers often stop erupting or erupt less frequently and with less volume, and springs dry up.
Although the first use of geothermal energy for electric generation occurred in 1904, geothermal energy production was initially concentrated in vapor dominated reservoirs that contain relatively large mounts of steam. Development where geysers were located did not occur until the 1950s, when there was a shift toward the use of geothermal systems that contain an abundant supply of heated groundwater relatively close to the surface. These systems were less expensive to develop, easier to find due to obvious geothermal activity at the surface, and more abundant worldwide (Duffield and Sass 2003, Rinehart 1980).
ourism Geysers and hot springs have also suffered impacts from human activities related to tourism, such as vandalism and infrastructure development. Throwing objects into geysers, whether to induce eruptive activity or simply for “good luck,” can change the delicate balance of water pressure and circula- tion (in essence, plugging the vent), resulting in alteration or cessation of the feature’s natural activity. Rocks, sticks, cloth- ing, coins, and numerous other items have been pulled from geyser vents. The circulation change can also change the water temperature, harming microbial algae mats that require spe- cific temperatures.
groundwater and steam create new channels that rob gey- sers and springs of water and heat needed to sustain pressure.
Development of tourist facilities such as roads, structures, walkways, and paths in thermal areas has undoubtedly dam-
Figure 2. Relative sizes of selected geyser basins (Steingisser 2006). Geyser counts include active, dormant, and extinct geysers, and do not imply that all were active simultaneously. Geyser counts at a location can vary from one researcher to the next. the counts shown here are based on the sources cited in the figure.
17(1) • 2009