[4] For about 12,000 years, Native American tribes built steambaths and thermal pools at the Geysers and used the steam and hot water for healing purposes, as well as spiritual and ceremonial practices, and cooking.

[6] The heated muds were used to soothe skin rashes and other aches and pains, using the fumaroles as a natural energy source.

[5] The Wappo also collected sulfur which they called te'ke and a Wappo village, named tekena'ntsonoma (teke sulphur + nan well containing water + tso ground + no'ma village) was located about 12 miles (19 km) southeast of Cloverdale and on the present-day Sulphur Creek.

[5] In 1938, the main building was destroyed in a landslide although the bar/restaurant, small cabins and the swimming pool stayed open, despite another fire in March 1957, until about 1979.

It is estimated that the development meets 60% of the power demand for the coastal region between the Golden Gate Bridge and the Oregon state line.

[15] Steam used at The Geysers is produced from a greywacke sandstone reservoir, capped by a heterogeneous mix of low permeability rocks and underlain by a silicic intrusion.

[8] However, since October 16, 1997, the Geysers steam field has been recharged by injection of treated sewage effluent, producing approximately 77 megawatts of capacity in 2004.

[21] The effluent is piped up to 50 miles (80 km) from its source at the Lake County Sanitation waste water treatment plants and added to the Geysers steam field via geothermal injection.

Since 2003, SRGRP has delivered approximately 11 million gallons per day of tertiary treated wastewater to replenish The Geysers’ geothermal reservoir.

In 2004, 85% of the effluent produced by four waste-water treatment plants serving 10 Lake County communities was diverted to the Geysers steam field.

[21] The injection of wastewater to the Geysers protects local waterways and Clear Lake by diverting effluent which used to be put into surface waters,[21] and has produced electricity without releasing greenhouse gases into the atmosphere.

[27] Before 1969, there were no earthquakes above magnitude 2 recorded by the United States Geological Survey (USGS) in an approximately 70 square miles (180 km2) area around the Geysers.

A large Bouguer Gravity anomaly combined with slower seismic velocities, located below the Clear Lake Volcanic Field, suggests a magma body is heating the geothermal area.