The Sacramento/San Joaquin Delta in California has been sinking since the early 20th century, putting its levee system at risk of failure and flooding. This could impact the water quality and supply for millions of people and agricultural land in California. The U.S. Geological Survey and California Department of Water Resources studied the causes of subsidence and carbon fluxes in the delta to understand these processes better. They found that the sinking land is a threat to the levees, which could lead to serious consequences for the region's water resources.