Residents and visitors have enjoyed the warm waters of Boyes Hot Springs, Agua Caliente and Fetters Hot Springs in the Sonoma Valley for over a hundred years. In many spots, the water that bubbles up is insulated by the surrounding porous soil. Cooled lava and tuff, a soft rock formed by cemented volcanic ash or dust, contain multiple pockets of air that assist with heat retention. There are also warm springs near Los Guilicos, in the canyon of Mark West Creek and near Geyserville.
Before the arrival of the first Spanish padres, Pomo groups in the Sonoma Valley enjoyed the springs. In 1834, Lieutenant Mariano G. Vallejo came at the direction of the Mexican government to secularize San Francisco Solano in Sonoma. Part of the land he controlled was called the Rancho Agua Caliente, which contained the springs of the Sonoma Valley.
“By the late 19th century, hot springs resorts and spas were all the rage in Europe and America. The timing was perfect for enterprising Sonomans to capitalize on the springs. Each of the springs…developed into their own communities (with which) the residents identified. Visitors, especially French, Italian and German, were drawn to resorts that catered to their interests,” said Patricia Cullinan, president of the Sonoma Valley Historical Society.
The arrival of the railroad made it easy to travel from San Francisco to the Sonoma Valley. Trains full of visitors came to the springs every weekend. They stayed for the warmth, scenery, opportunities for hunting and fishing, and fresh and plentiful food.
Medical research shows the health benefits of warm springs include increasing comfort and reducing blood pressure. Bathing in hot springs is not a substitute for medications that lower blood pressure. In addition, people must be cautious when getting out of a warm spring because they may feel dizzy from the drop in blood pressure.
Learn more about the springs of the Sonoma Valley at the Sonoma Valley Historical Society’s Depot Park Museum and the Marcy House Archives and Research Center in Sonoma. Visit depotparkmuseum.org.
