The Gila River and Little Colorado River adjudications trace their origins to proceedings initiated in the 1970s under the then-existing general adjudication procedures set forth in Arizona Revised Statutes sections 45-231 to 45-245. On April 26, 1974, the Salt River Valley Water Users' Association (SRP) filed a petition with the Arizona State Land Department (SLD) to determine the water rights in the Salt River above Granite Reef Dam (but excluding the Verde River). On February 24, 1976, SRP filed a similar petition for the Verde River and its tributaries. On February 17, 1978 and on April 19, 1978, utilizing these same statutes, the Phelps Dodge Corporation filed petitions with SLD to determine the water rights of the Gila River system and source and the Little Colorado River system and source. These petitions sought adjudication of the Upper Gila River watershed and of portions of the Lower Gila River watershed. On April 3, 1978, ASARCO, Inc. filed a petition with SLD for the adjudication of the San Pedro River and its tributaries.

On December 24, 1980, the Buckeye Irrigation Company filed a motion to intervene and a petition to enlarge the scope of the adjudication with respect to areas of the Gila River watershed not included in the previously filed petitions. This motion and petition were granted on March 17, 1981, and included the Agua Fria River watershed and portions of the Lower Gila River watershed. At the time, there was litigation pending in federal court which sought an adjudication of the Santa Cruz River watershed in Pima and Santa Cruz counties. Because of this litigation, the Maricopa County Superior Court, by granting the Buckeye Irrigation Company petition for adjudication of additional rights, did not include that portion of the Santa Cruz River watershed located in Pima and Santa Cruz counties. Following the conclusion of that litigation, on October 30, 1985, the Buckeye Irrigation Company filed a petition, granted by the Superior Court, for the inclusion of those portions of the Santa Cruz River watershed.

In April 1979, the Legislature amended the general adjudication procedures. Under these amendments, the Salt River, Verde River, and Gila River adjudications were transferred from SLD to the Maricopa County Superior Court. The San Pedro River adjudication was transferred to the Cochise County Superior Court. In November 1981, the Arizona Supreme Court consolidated these adjudications into one proceeding assigned to the Maricopa County Superior Court under the caption In re the General Adjudication of All Rights to Use Water in the Gila River System and Source, Nos. W-1, W-2, W-3 & W-4 (Consolidated).

Under the amended statutes, the Little Colorado River Adjudication was transferred to the Apache County Superior Court where it is litigated under the caption In re the General Adjudication of All Rights to Use Water in the Little Colorado River System and Source, No. 6417.

These cases were assigned to the Maricopa and Apache County Superior Courts because these are the counties where the largest number of potential claimants reside. Pursuant to the amended statutes, summons were issued in both adjudications and served on potential claimants in each watershed. Copies of the summons were served upon all persons listed in property tax assessments in each watershed and on all persons in the watershed who had, at the time, any kind of water rights filing on record with the Arizona Department of Water Resources (ADWR). In July 1984, a special notification was made to owners of registered wells in the Upper Salt River and San Pedro River watersheds. The summons required the filing of a statement of claimant with ADWR if the person claimed a water use from a well in the watershed.

Each watershed in the Gila River system was noticed. The original filing deadlines were:

Gila River Adjudication:

Upper Salt - June 30, 1980
January 4, 1985 (groundwater claims)
San Pedro - July 11, 1980
January 4, 1985 (groundwater claims)
Agua Fria - November 1, 1985
Upper Gila - November 1, 1985
Verde - November 29, 1985
Lower Gila - January 20, 1987
Upper Santa Cruz - August 3, 1987
Little Colorado River Adjudication:
December 23, 1985

Original deadline was May 1, 1982. Next deadline was set for June 30, 1985 after Supreme Court held that the McCarren amendment removed any federal impediment to Arizona state courts jurisdiction over Indian water rights.

Any person or entity who uses water or has made a claim to use water on property within the Gila River system or within the Little Colorado River system, potentially may be affected. The legislature has charged the Arizona Superior Court with quantifying and prioritizing validly existing water rights claimed in these watersheds. The final court decrees will establish the existence and ownership of claimed water rights, as well as important characteristics of the water rights including location of water uses, quantity of water used, and date of priority of the water rights.

The Special Master is a judicial officer appointed by the Arizona Superior Court to hear cases arising out of the adjudications and report on legal and factual issues designated by the Superior Court. After resolving all the objections to the hydrographic survey reports, the Special Master will present a report and recommended final decree to the Superior Court judge assigned to each adjudication. After hearing and resolving any objections to the Special Master's report, the judges will issue the final decree for each watershed. Special Master’s website.