Source - Economist, November 17, 2018: "Source of discord"
California's water infrastructure is primarily run by the state but there are dams and pumps that were built and are still run by the federal government. Both state and federal water entities must cooperate. Because of the 1902 Federal Reclamation Act states that state law supersedes federal law on disputes regarding water.
From the article: "Three-quarters of the state’s water falls as rain and snow north of the California delta. Three-quarters of the water is consumed south of it. A vast network of dams, canals and pumps shifts water from north to south. The system is an integrated one, but when it was planned in the 1930s (during the Depression), the state could not afford to finance the whole project. The federal government stepped in and built (and still manages) many of the dams and pumps. Operationally, the two sides need to work together. Over the years demands on the system have increased. There is not enough water to satisfy farmers, city dwellers, fishermen, environmentalists, and so on—and conflicts have to be resolved by two groups of managers, not one. To make matters worse, climate change and a six-year drought that ended in 2017 have increased the stress on the hydrology of the state, forcing a further squeeze on users and ever-tougher choices."
"In July the Bureau of Reclamation, the federal agency that oversees water management, threatened to sue California’s water board, arguing that its plan to keep more water in the state’s two largest rivers would unfairly reduce the amount diverted away for agricultural and urban use. The secretary of the interior then threatened to break off relations between the federal government and state water managers unless the state dropped its plan. At the same time, the bureau said it wanted to renegotiate a landmark agreement of 1986 which governs how much water federal and state agencies may pump out of the delta formed by the Sacramento and San Joaquin rivers. The California delta is the largest estuary on America’s Pacific coast and the source of water for 25m people. All this seemed straight out of Mr Trump’s playbook: bluster, threaten to rip up an old treaty and try to impose a new one. This example might seem doomed to fail for legal reasons. Normally in federal matters, federal law outranks state law. But water is different. An act of 1902 (the Federal Reclamation Act) says that state law precedes federal law on disputes about water, even regarding dams and levees run by the federal government. A federal law concerning California, the Central Valley Improvement Act of 1992, reasserted the primacy of state law and was confirmed by the Supreme Court. Whatever Mr Trump’s administration may think, the feds must abide by Californian law, not the other way around."