Allocating shortage amongst riparian and appropriative water right holders in California's drought

Abstract:

Within California’s water rights system, water users have different priorities to available water during drought. Higher priority users are less likely to face shortage due to the demands of other users, but may be limited by reduced availability of water. An integrated set of water right allocation models was developed to determine optimal allocation of shortage for riparian and appropriative water right holders, which also allows for including required flows for the environment and public health and safety, and operational reliability for senior water right-holders. Riparian water right holders have equal priority, with water shortage allocated as an equal proportion of normal diversions for all riparian users within each sub-basin. These proportions are determined by water availability, with downstream users likely to receive higher proportions due to downstream accumulations of streamflow. Appropriative users as a class have a lower priority than riparian users. Shortages allocated among appropriative water right holders are made strictly by water right seniority.