Continued funding for a giant underground tunnel that would reroute part of drought-prone California's water supply was approved by the Metropolitan Water District of Southern California.
The $142 million in funds for pre-construction and planning costs is key to the Delta Conveyance Project, which state officials have described as critical to water supplies and transport around the state due to aging infrastructure and climate change-related shifts in precipitation.
California's water supply relies on a complex system of channels, aqueducts, dams and reservoirs to deliver water to homes, farms and businesses in the nation's most populous state. Much of it was constructed 50 or more years ago.
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The network of waterways that makes up the Sacramento-San Joaquin Delta would include a 45-mile long tunnel, if the Delta Conveyance Project moves forward with a key vote expected in 2027.
"After careful consideration, our board took this step because it allows us to gather critical information about the project’s benefits and costs that will allow us to evaluate whether we will participate in the full construction of the project," said Metropolitan board Chair Adán Ortega, Jr. said in a statement.
The Metropolitan Water District of Southern California is the largest of dozen agencies that vote to continue funding for preconstruction and planning. Gov. Gavin Newsom has been a major supporter of the project.
"Nothing else comes close because nothing is more important," Newsom said earlier this week. "Because this impacts 27 million Californians."
The tunnel would be designed to move more water from north to south during California's winter storms, some of which are fueled by atmospheric rivers and are capable of bringing days of rain and mountain snow. California faces extreme variability when it comes to winter precipitation with both extremely wet and dry years.
About 50 percent of California's total precipitation fall in about five to 15 days each year, according to the state Department of Water Resources. That's a small window to replenish mountain snowpack and water reservoirs.
Two-thirds of the state's water supply relies on snowfall in the Sierra Nevada Mountains, which acts as a giant natural reservoir with the snowpack melting in spring and early summer, then flowing into the state water system.
Southern California receives about 30 percent of its water from the State Water Project.
Critics have said the tunnel project's $20 billion price tag is too high and point to other options to improve the sprawling state water system with less impact to the Sacramento-San Joaquin River Delta’s ecosystem.
Barbara Barrigan-Parrilla, executive director of Restore the Delta, said the tunnel aims to transport too much water to farm operations that should be scaling back on water use as the state faces a potentially drier future. California grows much of the country's fresh produce.
“There are certain elements that just want to build things for the sake of building things rather than doing the analysis of building the right things,” she said.
The tunnel has drawn widespread opposition from Central Valley communities that say it would harm their economies and the delta. Last year, the state completed a key environmental review for the project, but it still must pass additional review and obtain various state and federal permits.
The Associated Press contributed to this report.
