SACRAMENTO (CN) – Overpumping of California’s dwindling groundwater supply is causing the Central Valley to sink at a historic pace, in some places 2 inches per month, according to a NASA report released Wednesday.
Satellite and aircraft images revealed sinking basins throughout the state, including an area near the California Aqueduct that sank 8 inches in four months last year. Land in the Tulare basin near Corcoran sank 13 inches in an eight-month stretch, according to the NASA report .
Scientists and state officials warned that if the land continues to subside so rapidly, nearby roads and water infrastructure could be affected soon.
“Roads can be broken by fissures, pipelines have been exhumed and the slope of the land can be altered, changing drainage patterns,” the report states.
Faced with reduced federal and state surface water deliveries, farmers across the Golden State have been pumping groundwater at an unmatched pace.
“Because of increased pumping, groundwater levels are reaching record lows – up to 100 feet lower than previous records,” Department of Water Resources Director Mark Cowin said in a statement.
Reactions to the long drought – generally reported as 4 years long, though some climatologists say it has been going on for 16 years – have accelerated land subsidence. In some areas the land has been sinking nearly 2 inches per month.
The Central Valley aquifer, below the state’s most fertile and productive farmland, stretches 400 miles from north to south and is the state’s largest source of subterranean water. The aquifer has collected water for thousands or millions of years, but researchers say the water bank is shrinking and there is no regulatory system to monitor how much is being withdrawn.
While lawmakers approved the state’s first groundwater monitoring program last year, it’s still being developed and does not become law until 2020.
“Groundwater acts as a savings account to provide supplies during drought, but the NASA report shows the consequences of excessive withdrawals as we head into the fifth year of historic drought,” Cowin said.
The regulator is developing a $10 million plan to help communities monitor and prevent further subsidence in the Central Valley and protect infrastructure, including canals, aqueducts and bridges.
Manmade contamination of the state’s largest reservoir is also an issue, according to a study released this week by the University of Nebraska-Lincoln. The study found that natural uranium levels in the aquifer far surpass Environmental Protection Agency guidelines and that the contaminated samples are linked to nitrates, a common ingredient in fertilizers.
As the state scrambles to conserve water supplies through mandatory water restrictions, the agricultural industry continues to take the biggest hit. Economists estimate the industry will lose $1.84 billion to drought this year, including 10,000 jobs and more than 500,000 fallowed acres.
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