In the Golden State most precipitation falls in the northern and eastern parts, whereas most of the water demand is in the central, west and south parts. Moreover, California faces extreme variability in precipitation, which is expected to worsen with climate change.
California’s Water Resilience Portfolio is the state’s roadmap to prepare the state’s water systems for a warmer, more variable climate, including actions to maintain and diversify water supplies, protect natural ecosystems, and improve infrastructure to store, move and share water. A key part of the portfolio, an essential for climate adaptation according to the California Department of Water Resources (DWR), is the Delta Conveyance Project, which the DWR started planning in 2020, and after extensive environmental review, received approval last December. The project has thus moved forward to a phase of further engineering, design and permitting.
The project intends to modernise the state’s water infrastructure to, among other things, capture and move more water during wet seasons to better endure dry seasons, minimize losses from climate-driven weather extremes, and protect against earthquakes disrupting water supplies. Specifically, the proposed Delta Conveyance Project, known as the Bethany reservoir Alternative, involves constructing new conveyance facilities in the Delta that would add to the existing infrastructure of the State Water Project (SWP): two new intake facilities, a tunnel and a pumping station.
The State Water Project, built in the 1960s, delivers water from the Sacramento-San Joaquín Delta to other regions in the state, down to southern California. Owned and operated by the DWR, it is a water storage and delivery system that includes canals, pipelines and reservoirs to deliver water for more than 27 million people, as well as agricultural land and business.
Plans for the Delta Conveyance project, in its present form or earlier versions, have been de subject of controversy for decades, as project opposers fear it will destroy de delta’s fragile ecosystem, informs the Los Angeles Times. They argue it would significantly change the delta’s hydrology, diverting more water, increasing the estuary’s salinity and worsening water quality.
The current concept would have a cost of $16 billion and a 45 mile tunnel with an internal diameter of about 36 feet (about 11 metres), and would be buried about 140-170 feet (43-52 metres), which would make it one of the longest water tunnels in the world if completed.
The DWR claims that, had it been operational at the end of 2021, when California received record-breaking amounts of precipitation, the Delta Conveyance Project would have captured additional water - enough water to meet the needs of over 2.5 million people for a full year. Similarly, this year it could have captured water for 5 million people for a year during the rain events in January and February, and such opportunities are expected to be more common as the state receives more rain instead of snow as a result of warmer temperatures.
Moreover, the proposed tunnel should be able to withstand an earthquake better than the existing levees in the delta: DWR’s Director Karla Nemeth said that the potential impact of a powerful storm or earthquake to breach one of the levees “keeps me up at night”, as it could endanger the water supplies for 27 million people.
Still, opponents say the money would be better spend on supporting levees and restoring the floodplain to reduce flood risk, in addition to changing water management to protect the delta. Threats to water quality, fish and wildlife in the delta are a significant issue for communities around the delta, once a thriving wetland that provided livelihoods to Indigenous groups.
State officials hope to address some of those concerns through a Community Benefits Program for local communities, which includes a fund for projects geared to recreation, air quality, habitat conservation and other local priorities.
At the root of the dispute about the project’s merits is, as usual with these types of projects, who receives the benefits (water users elsewhere in California) and who endures the costs (communities around the delta), but also whether such a high-cost investment will be able to provide the water availability that officials expect from it, and whether other alternatives to increase water resilience make more sense. Water from the SWP is a portion of the state’s water portfolio, which includes as well groundwater and the Colorado River. To increase water resilience, the state and water agencies are pursuing numerous local projects that include recycling, groundwater recharge and desalination, in order to reduce reliance on water from the SWP in the future, as well as efforts to increase water conservation and efficiency.
