Putah Diversion Dam diverts water into Putah South Canal about 6 miles (9.7 km) downstream of Monticello Dam. The dam is a gated concrete weir structure with an earth-fill embankment wing. It creates the small Lake Solano, which has a capacity of only 750 acre-feet (930,000 m³).
The canal is entirely concrete-lined except for a mile (1.6 km) of pipe called the Putah South Pipeline. Most of the lands are below the level of the canal and are served by gravity. Lands above pump water straight from the canal. The canal ends at Terminal Dam, which is made from earth-fill.
The dam forms a small 119 acre-foot (147,000 m³) reservoir. The reservoir supplies drinking water to the city of Vallejo. Most of the canal is operated by Solano Irrigation District, but the Bureau of Reclamation operates the headworks.