Limiting exports from the Delta to 3 MAF a year is based on water realities. Even in 1960, the men planning the State Water Project knew that was all they could reliably get out of the Delta.
A graph in Bulletin No. 76, Delta Water Facilities (1960), shows that any demand over 3 MAF a year would have to be met from sources that were never developed.
“Full demands on the State Water Resources Development system can be met until about 1981 from surplus water in and tributary to the Delta with regulation by the proposed Oroville and San Luis Reservoirs,” planners wrote in Bulletin No. 76. “However, upstream depletions will reduce the available surplus supplies and water will have to be imported from north coastal sources after that year.”
They projected a statewide demand of 8 MAF by 2020. That left them with a shortfall of 5 MAF, and they planned to find that by diverting water from north coast rivers. But beginning with the passage of the California Wild and Scenic Rivers Act in 1972, those north coast rivers became unavailable for development.
That was the point at which every region of California should have started looking closer to home for additional water to meet local needs.
Instead, agricultural and urban development statewide climbed just as if that extra 5 MAF of water were available. A burgeoning addiction to water transfers was fed by unsustainable allocations from the State Water Resources Control Board under pressure from the state and federal water contractors.
In 1992, the State Water Resources Control Board found that Delta pumping in wet years should not exceed 2.65 MAF in order to provide the necessary outflows to protect fish and the Bay-Delta and Estuary ecosystems. And in fact, as exports from the Delta rose above 2.5 MAF a year, the health of multiple species of fish declined.
Those planners 50 years ago were right: 3 MAF a year is the maximum that should be taken from the Delta.
Three MAF is still the number to aim for, and we don’t need any conveyance to get it. Certainly not the 9,000 cubic foot per second (cfs) proposed by the thirsty state and federal water contractors. But not a 3,000 cfs conveyance facility, either, offered as a compromise but still taking additional water the system can’t spare. And not a facility to take water from any other part of the Delta.
The three MAF a year average can be taken most years using existing through-Delta conveyance. If the water isn’t available, it’s because California is having one of its periodic droughts, and then everyone in the state has to pull together to cut consumption.