What is subsidence?

California’s Delta was once the largest freshwater estuarine wetland on the west coast of North America. Beginning in the 1880s, agricultural interests started to drain the marsh islands and protect them with levees. The reclaimed islands yielded some of the state’s most productive farmland. However, land drainage in the Delta has caused extensive oxidation of peat soils, which causes subsidence (the loss of land elevation). Subsided lands continue to pose significant challenges for people living and working in the region, including increased costs to drain soils, declining arability for agricultural production, degraded water quality, increased vulnerability to levee failure and flooding, and substantial emissions of greenhouse gases in areas where peat soils remain.

About the Delta ISB

The Delta ISB provides oversight of the scientific research, monitoring, and assessment programs that support the adaptive management of the Delta through periodic reviews. Prior to undertaking a major review, the Board prepares a brief prospectus describing the review’s purpose and process based on engagement with interested parties, including agencies.