Areas Of San Joaquin Valley Sink Further In 2016, Officials Blame Groundwater Pumping

SACRAMENTO (CBS Sacramento) – Radar satellite maps created by NASA show land continues to sink rapidly in certain areas of the San Joaquin Valley, putting state and federal aqueducts and flood control structures at risk of damage.

An August 2015 NASA report documented record rates of subsidence or sinking in the San Joaquin Valley, particularly near Chowchilla and Corcoran, as farmers pumped groundwater in the midst of the historic drought.

CBS13 ARCHIVE: Damage From Sinking Land Is Costing California Billions

The report released Wednesday shows that two main bowls covering hundreds of square miles where the ground is sinking grew wider and deeper between spring 2015 and fall 2016, according to a statement from the Department of Water Resources.

DWR also reported intensified subsidence at a third area, near the city of Tranquillity in Fresno County, where the land surface has settled up to 20 inches in an area that extends seven miles.

"The rates of San Joaquin Valley subsidence documented since 2014 by NASA are troubling and unsustainable," said DWR Director William Croyle.  "Subsidence has long plagued certain regions of California.  But the current rates jeopardize infrastructure serving millions of people.  Groundwater pumping now puts at risk the very system that brings water to the San Joaquin Valley.  The situation is untenable."

Groundwater wells near state infrastructure could be contributing to the subsidence recorded by NASA, says the agency.

There has been no comprehensive estimation of damage costs associated with subsidence.  Subsidence-related repairs typically covered in the cost of maintenance have cost the state an estimated $100 million since the 1960s.

Areas of concern include the California Aqueduct, the main artery of the State Water Project, the Delta-Mendota Canal, and the Eastside Bypass, which have all seen the effects of subsidence.

In response to the new findings, state officials said they will investigate any legal options available to protect state infrastructure.