After years of negotiations and studies by concerned producers in the Chino Basin, a California Senate bill was introduced and approved by then Governor Ronald Reagan in 1975. This resulted in a judiciary process that began in 1977 and in 1978, resulted in a Judgment entered into the San Bernardino County Superior Court establishing the Chino Basin Watermaster.
During the three years prior to the 1978 Judgment, three committees were formed representing the three major types of water right holders within the Chino Basin. Overlying landowner-based rights holders were represented by two Pool Committees: the Overlying (Agricultural) Pool, representing farmers, the State of California, and other minimal producers; and the Overlying (Non-Agricultural) Pool representing businesses and industries. Appropriative water right holders (cities, agencies, and other water suppliers) were represented in the Appropriative Pool.
Representatives from each of the three Pool Committees formed the Advisory Committee. The Advisory Committee ratifies the consensus among the three Pools on any given matter.
The 1978 Judgment adopted and mandated the continuance of the Pool and Advisory Committees, and also created a special master of the Court called Watermaster. Initially the Watermaster duty to enforce the Judgment was assigned to the Chino Basin Municipal Water District (CBMWD) Board of Directors, with staff from that agency carrying out the administrative duties of Watermaster. The Chino Basin Municipal Water District became known as the Inland Empire Utilities Agency in 1998.
In 1998 the Court issued an Order that assigned the duty to enforce the 1978 Judgment to a new Watermaster Board, independent of CBMWD. In addition to enforcing the Judgment the nine-member Board was also tasked with creating an Optimum Basin Management Plan. The Watermaster retained separate counsel and hired staff and consultants to carry out its duties.