Rancho Agua Caliente was a 3,219-acre (13.03 km2) Mexican land grant in present day Sonoma County, California given in 1840 by Governor Juan Alvarado to Lázaro Piña (often misspelled as "Pena" in historical documents). The name means "warm water" and refers to the hot springs in the area. The grant extended two and one half leagues to the north of Sonoma and was one quarter league wide, and included present day Glen Ellen and Fetters Hot Springs-Agua Caliente.