Monticello Dam Overlook, Thayer

Putah and Cache: Monticello Dam

The Monticello Dam Overlook

Robert Thayer

At Devils Gate, the Monticello Dam now spans Putah Canyon's walls. Devil's Gate was a dam builder's dream: a narrow notch in the upturned strata of Blue Ridge, layered of Venado formation marine sandstone from the Cretaceous period, originally laid down in the Pacific Ocean far from shore.

The Monticello Dam overlook is an increasingly popular place as people begin to learn more about their watershed. Built by the United States Government and Solano County (Napa and Yolo Counties opted out) in the mid 1950's, Monticello Dam is operated by Solano County and the resultant reservoir is managed by the U.S. Bureau of Reclamation. The reservoir has a drainage basin of about 360,000 acres, and at normal annual rainfall, it would take 4.5 years to fill up if outflow, infiltration and surface evaporation were ignored and "zeroed out". However, the winters of 1994-95, 95-96, and 96-97 were wet enough to fill the reservoir completely and spill water down the large "Glory Hole" spillway drain visible just beyond the dam. Named for the Morning Glory flower whose shape it resembles, it draws numerous visitors, and its eerie image is captured in many a photograph.