Major California rivers drain into the Sacramento-San Joaquin Delta, and over decades of building dams and reservoirs and pumps, it’s become the major hub of the state’s water system. It’s not just the water flow that’s been transformed here, however. This land used to be made up of tidal wetlands and marshes of tullies. Today, there are nearly 60 islands surrounded by levees. Most of the land here is used for farming, and it’s some of the richest farmland in the state.