1959 Map of Twitchell Dam

About this map

Twitchell Dam and its newly formed Twitchell Reservoir anchor this 1959 study of the rugged interface between San Luis Obispo and Santa Barbara counties. The map documents a critical hydrological junction where the Cuyama River and Sisquoc River converge to form the Santa Maria River. This area is defined by the transition from the steep San Rafael Mountains down into the Santa Maria Valley, a landscape managed by a complex network of engineering features including a Spillway Tunnel, Gaging Stations, and extensive Levees. Rural settlements like Garey, Gates, and Rex appear alongside the expansive Santa Maria Grant boundary, illustrating the persistence of older land divisions. The presence of numerous Oil Wells in the southern canyonlands highlights the region's mid-century petroleum industry amidst family-named landmarks like Fulger Point and Cañada de los Coches.