California built a $20 billion rainwater storage tunnel

A giant tunnel used to collect and store rainwater will help California cope with prolonged drought caused by climate change .

The administration of California governor Gavin Newsom announced in mid-May a plan to spend more than $20 billion to build the Delta tunnel to collect more water when it rains and store it to better prepare for prolonged droughts. long period of time caused by climate change, according to Independent .

The Sacramento-San Joaquin River Delta seen from above. (Photo: Times of San Diego).

State authorities have been trying to build a water storage tunnel system for decades. The most recent version approved by the California governor is one giant tunnel instead of two tunnels as proposed by his predecessor Jerry Brown. According to Newsom's administration, California could collect more water from the Sacramento River during major storms and pipe it south for storage. The most recent cost estimate in 2020 showed the tunnel project cost $16 billion . New analysis shows the tunnel would cost $20.1 billion due to inflation. The project will be paid for by 29 local public water agencies with customer revenues.

Analysis conducted by Berkeley Research Group shows that the tunnel will bring benefits of up to $38 billion, mainly due to increased water supplies that help better respond to natural disasters such as earthquakes. "The benefits are clearly worth the costs ," said David Sunding, professor emeritus at the University of California, Berkeley, who led the analysis.

The new tunnel will be part of the State Water project, a complex system of reservoirs, dams and canals that supplies water to 27 million people and irrigates 303,515 hectares of farmland. Climate change is threatening the state's water resources. A recent drought caused water levels in reservoirs around California to drop to dangerous levels, even leading some hydroelectric plants to shut down. State authorities predict that by 2070, water supplies will decrease by 22% due to climate change.

The proposed tunnel would be 72 km long and 11 m wide, large enough to carry nearly 610 million liters of water per hour. The tunnel would transport water from the Sacramento River around the Delta to a reservoir near Livermore.

State authorities say the tunnel will allow the state to collect more water when California is hit by "atmospheric rivers," major storms that can flood the state for weeks during the rainy season. According to the analysis, the tunnel will increase water supply by 17%, nearly enough to reduce the decrease caused by climate change.