During his tenure as a lawyer, Carlos also represented numerous clients in the Gila River and Little Colorado River Stream Adjudications. His clients in these proceedings have included municipalities, irrigation districts, and numerous mining, farming and power companies, all of whom were located in watersheds tributary to the Gila River. As a consequence, these entities and many others are subject to the ongoing adjudication of the rights to water from the Gila River and its tributaries. During this time period, much of the litigation focused on whether groundwater should be included in an adjudication that was primarily designed to determine surface water rights. See, Matter of Rights to the Use of the Gila River, 171 Ariz. 230, 830 P.2d 442 (1992, referred to as Gila River I); Gila River II, 175 Ariz. 382, 857 P.2d 1236 (1993); Gila River III, 195 Ariz. 411, 989 P.2d 739 (1999); Gila River IV, 198 Ariz. 330, 9 P.3d 1069 (2000); and San Carlos Apache Tribe v. Superior Court, 193 Ariz. 195, 972 P.2d 179 (1999).

As part of his representation of several ranching families in these adjudication proceedings, Carlos worked with the Arizona Cattle Growers Association and the Arizona State Land Department to draft and pass legislation to clarify ownership of the rights to water used on state trust land. When challenged by several Indian Tribes, these provisions were expressly upheld by the Arizona Supreme Court. San Carlos Apache Tribe v. Superior Court, 193 Ariz. 195, 216-217, 972 P.2d 179, 200-201 (1999).

In the Little Colorado River Adjudication, Carlos represented a major electric utility, and also a ranching family that claimed water rights for the irrigation of approximately 1,500 acres of land. These lands were eventually conveyed to the U.S. Forest Service for wildlife conservation purposes, as described below.