The Solano Project took shape in the 1940s, when the Solano Irrigation District organized to manage the water resources of Putah Creek. On November 11, 1948, the Secretary of the Interior formally authorized construction. The Bureau of Reclamation built the dam between 1953 and 1957 - a 304-foot concrete arch spanning the narrow canyon where Putah Creek flowed through the Vaca Mountains. The result was Lake Berryessa, California's seventh-largest man-made lake, holding 1.6 million acre-feet of water across 20,700 surface acres. A powerplant completed in 1983 added three generators producing 11.5 megawatts, sending electricity to the North Bay. The dam's primary mission, though, has always been irrigation: the 33-mile Putah South Canal distributes water to farms throughout Solano County, and a 1999 contract provides for delivery of 207,350 acre-feet annually.

Building the dam meant killing a community. The inhabitants of Berryessa Valley vehemently opposed the project. Even the city of Winters, which stood to benefit from the new water supply, fought against it because of close social ties to the town of Monticello. Opposition changed nothing. Land purchases began in 1953, though residents were allowed to remain until rising water actually reached their property. Most of Monticello's people left by summer 1956. Crews then moved through the valley, cutting down trees, demolishing homes, tearing out infrastructure. About 300 graves had to be relocated to higher ground. Photographer Dorothea Lange documented the town's final days for what she intended as a Life magazine feature. The magazine never published it, but the images survived - a record of what progress costs when progress needs your valley.

The Glory Hole is an uncontrolled morning-glory-type spillway, meaning it operates passively whenever the lake reaches its maximum elevation of 440 feet. Water simply flows over the circular concrete lip, spiraling downward through a vertical shaft and then through a horizontal tunnel that exits below the dam. For years at a time, the spillway sits dry and exposed, its concrete funnel gaping at the sky like an empty eye socket. Then the rains come. In February 2017, after storms raised the lake level 35.5 inches in six weeks, boaters grew so eager to witness the spillway's activation that they generated enough wake to push water over the rim prematurely at 1:45 p.m. on February 13. The official spill began three days later, on February 16, for the first time in over a decade. It spilled again in February 2019.

Swimming near the Glory Hole is prohibited, and the prohibition exists for the most direct of reasons. In 1997, Emily Schwalen of Davis was swimming near the spillway when she was caught in the current. She managed to hold onto the concrete rim for approximately twenty minutes before the water pulled her over the edge and down the pipe. She did not survive. It remains the only known death from the spillway drain, but one death was enough to cement the Glory Hole's reputation as something more than a curiosity. The smooth, almost gentle appearance of the water flowing over the lip conceals enormous hydraulic force. Warning buoys mark the exclusion zone, and signs are explicit. The spectacle is best appreciated from shore.

Lake Berryessa once drew 1.3 million visitors annually. That number has dropped below 400,000, a decline driven not by the lake's appeal but by bureaucratic mismanagement. In 2008, the Bureau of Reclamation attempted to install a new concessionaire, Pensus Inc., to operate the resorts around the lake. The transition failed badly. Local resort operators were forced out without proper compensation, and the Bureau demolished their facilities. The economic collapse rippled through the surrounding community. Meanwhile, the dam itself continues doing what it was built to do: the reservoir has prevented an estimated $5 million in flood damages since 1957, and the water keeps flowing to Solano County's farms. The environmental costs are measured differently - reduced groundwater recharge, deteriorated sandbars, and declining cottonwood and willow populations along Lower Putah Creek.