[Kalium]

From a system perspective, the system functions better when everyone is incentivized to measure and ensure efficient use. That water both comes from and returns to the big river in time does surprisingly little to mitigate the basic limits of how much water is going in and out at any given time.

[jeffbee]

Please speak in concrete terms. Which inferior rights holder would get more water, and how much more, if Sacramento City had more meters?

[Kalium]

I don't think there is a simple concrete answer to that, because that answer lies on the far side of quite a few uncertainties. The answer is probably a number of them, because after investing in metering and efficient usage the City of Sacramento would likely use significantly less water.

If nothing else, the big river would have more water.