From a new Public Policy Institute of California white paper on water allocation reforms:
Regions with drought-prone climates need reliable accounting of water availability and use. Authoritative water accounting is a foundation for the transparent, reliable, timely administration (and, if necessary, curtailment) of water rights, management of groundwater, and water trading. This drought spotlighted serious gaps and fragmentation in California’s water accounting system, hampering such actions.
Importantly, according to authors Brian Gray et al., California law does not now have a framework for measurement return flows, the water returned to the system (through agricultural drainage back to a river or groundwater recharge):
Understanding net water use (the amount applied minus return flow) is key to understanding water availability and also the amount of water that can be traded without harming other water users.
California also suffers from a lack of clarity of the place public health and safety, and the environment, have in the water rights priority queue:
The water board does not have a clear policy to take public health and safety or the environment into account when ordering surface water curtailments, even though an array of laws designates these public interests as priorities that may take precedence over senior water rights. So far, this omission has been especially costly for the state’s stressed riverine and wetland ecosystems.
The proposed solution:
Adopt a process for the local development of watershed-based environmental flows, combining a state mandate and local authority to flesh out details (water board and local action).
There is much more, a very rich and thoughtful package of actionable recommendations.