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The Geysers

In the late 1800s, Lake County’s Cobb Mountain was a mecca for spa-goers who came from far and wide to “take the waters,” but today is home to the largest complex of geothermal plants on earth.


A natural wonder created by the Clear Lake Volcanic Field, hot springs are the result of ground water that has been intensely heated by magma exceeding 5,000º F. The heated water collects in underground pockets called geothermal reservoirs. Water from the reservoirs escaping through the earth’s crust as steam are known as fumaroles; geysers are gushes of boiling water escaping in spurts; hot springs occur when the water bubbles into shallow bowls in the earth.


Many of the naturally therapeutic hot springs began to recede underground in the early 1900s. At about the same time, the town of Larderel, Italy, paved the way for “green energy” production when industry pioneers began utilizing underground springs to generate electricity.


Development of the geothermal fields on Cobb Mountain began in the 1950s. Today, the Geysers facility is a portfolio of 18 geothermal power plants, which are fed by more than 350 wells, producing enough clean, renewable energy to power 850,000 homes. Partnership with the local government has resulted in ecologically sound solutions for Lake County’s water and energy needs, such as recycling wastewater from area communities.


The Calpine Geothermal Visitor Center is located at 15500 Central Park Road in Middletown, just off Highway 29. (866) GEYSERS.

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