A giant, 45-mile long underground tunnel is at the heart of a new plan to move water from California’s wetter north to its parched south.
The scheme would see water removed from the Sacramento River, the state’s largest, to the California Aqueduct which currently ends near Santa Barbara and San Bernardino in the state’s southern portion.
A report looking into the project said the 10-year construction would require removing 71 buildings, including 15 homes, as well as taking over 2,340 acres of farmland and running through sites significant to tribal communities.
It could also harm two types of fish – the Delta smelt and the endangered Chinook salmon – and adversely affect water quality by increasing the amount of bromide, chloride and salt content.
But the feasibility study said all that, would still result in less negative consequences than other options that have been on the table for dealing with southern California’s drought, for the past 50 years.
The preferred plan for the huge tunnel would be to build two stations to pull water from the Sacramento River near the state’s capital, then carry it south before breaking off at the top of the California Aqueduct, the state’s main channel for moving water south, built in the 1960s.
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Two in three Californians, or about 27 million people, rely on water that comes from the Sacramento-San Joaquin River Delta.
At the southern end of the Delta, state and federally-run pumping plants currently suck up the water and send it south. The proposed tunnel project would take the water from the Sacramento River before it reaches the Delta.
The Metropolitan Water District of Southern California is the state’s largest water contractor, using water from the Delta to supply 19 million people, including the city of Los Angeles.
Adel Hagekhalil, the company’s general manager, said they were working to expand its supply from other sources, but the tunnel project was “critical to provide flexibility and ensure the state is capturing all of the water it can”.
How much does a giant tunnel cost?
State water officials say a tunnel is badly needed to modernise the state’s water infrastructure in the face of climate change, which scientists say is likely to cause both prolonged droughts and major deluges of rain and snow.
It would also better shield the state’s water supply from the risk of an earthquake that could cause levees (a natural or artificial wall that dams water) to crumble and ocean salt water to flood into the system.
Though California is in the third year of a punishing drought, it saw record rainfall last October and another major dump of rain and snow in December, some of which the state was unable to capture.
The cost of building the planned tunnel has not been revealed though a prior estimate for a different route was estimated to be about $16 billion (£13 billion).
It would be paid for by the water companies that would use it but even if state politicians agree to go ahead with the plan, is unlikely to begin until at least 2028 and would take more than a decade to build.