Historical Background for the Alto Subarea of the Mojave Adjudication

In 1996, the Final Judgment in the Mojave River Basin Adjudication established a “physical solution” to address overdraft conditions and ensure that downstream users received sufficient surface or subsurface flow from upstream areas.  The basin was divided into five hydrologically-related, but distinct subareas, and water supplies within the subareas were apportioned among the producers.

A Base Annual Production (“BAP”) right was established for each producer in the basin.  BAP is a producer’s maximum annual production from 1986 to 1990 and is used to determine the producer’s proportional share of the available water supply each year.  BAP can be permanently transferred either independently or appurtenant to land.

In the first five years following entry of the judgment, the total BAP in each subarea was ramped downed from 100% to 80%, and each year the watermaster evaluates conditions and determines if further ramp down is needed.  The ramped down annual supply is allocated to the producers as Free Production Allowances (“FPA”).  FPA specifies the amount of groundwater that holder can pump with incurring a replenishment obligation.  Unused FPA can be carried over to the following year.  Both FPA and carryover water can transferred to another water user, who can use it to meet a replenishment obligation or to increase their allowed pumping for that year.

While transfers of BAP, FPA and carryover water occur in all five subareas, markets have developed in the Alto subarea, which includes most of Southern California’s high desert communities.