Stopping Subsidence

Long Beach was once called the Sinking City. Oil and gas extraction from the Wilmington Oil Field caused the land surface to collapse into a subsidence bowl stretching more than 20 square miles, from the Port of Long Beach to Seal Beach. At its deepest point, the ground dropped 29 feet. Infrastructure cracked and buckled. Flood damage was extensive, and the costs were enormous.

The turnaround began in the 1950s, when the City of Long Beach demonstrated that injecting water back into the oil-bearing formations could repressurize the reservoir, stop subsidence, and actually increase oil recovery. In 1958, the California Subsidence Act was passed, enabling coordinated waterflood operations across fault block units. By 1966, subsidence had stabilized. In some areas, the ground later partially rebounded.

Subsidence monitoring has never stopped. The Long Beach Energy & Environmental Services Department conducts elevation surveys on a regular schedule across the city, using a mix of satellite imagery, GPS technology, and traditional leveling methods. Stable ground is not taken for granted here. It is actively managed every day.