Which dam provides the largest water supply for agricultural and urban use in California?

Shasta Dam is recognized as the largest water supply source for both agricultural and urban use in California due to its substantial reservoir capacity and strategic position in the state's water infrastructure. The dam is located on the Sacramento River and plays a crucial role in the Central Valley Project, which is essential for distributing water to vast agricultural regions in California's Central Valley, as well as providing municipal water supply.

Shasta Dam's significant capacity allows it to store large volumes of water during the rainy season, which can then be released during dry periods to meet irrigation and urban demands. The reservoir created by the dam, Shasta Lake, not only serves agricultural needs but also provides recreational opportunities and contributes to flood control.

While other dams listed, such as Oroville Dam and Folsom Dam, also have important roles in California's water management system, they do not match the scale of water supply provided by Shasta Dam. Proper understanding of the roles of various dams is vital in managing California's complex water needs effectively.