> Water use in California is divided into approximately 51% for environmental uses, 39% agricultural use and 11% urban uses, though that varies considerably between regions and between wet and dry years. Solely relying on these statewide volumes is controversial because they don't consider the fact that most of the volume of water used for environmental purposes includes flows down Wild and Scenic Rivers in the North Coast where there is no practical way to recover it for either agricultural or urban use because it lacks many connections to the statewide water supply system. It also doesn't factor in the amount of water required to keep salty water from the Pacific Ocean from intruding into the Delta beyond a certain small concentration.

If we set aside the 51% of California's water that isn't actually used by people, that 39% of total water becomes 79.6% of water used. So, yeah, 80% of usage.

This is completely false. The federal Central Valley Project that the article concerns is a major water delivery system that is key to much of the state.

(There are other federal roles beyond the CVP in California water supply—e.g., there is a federal role in Colorado River water management, but the CVP is the big, big federal involvement.)

> If it gets declared a disaster then Federal disaster relief will try to help. So 0% of the extra water brought in for disaster relief will go to farmers.

This has nothing to do with disaster relief. This is allocation of the water flow through the CVP, which is routine supply, not something that only kicks in in a disaster.

> The 80% figure is farm use of water in the state.

No, it's the ag share of non-environmental water use in the state.