Opinion ID: 1253871
Heading Depth: 2
Heading Rank: 2

Heading: on groundwater, surface water, subflow, and the reserved water rights doctrine

Text: ¶ 6 The trial court held that federal reserved rights apply not only to surface water and subflow, appropriable categories under Arizona law, but also to non-appropriable groundwater. The court also held that federal reserved rights holders are entitled to protection from any off-reservation groundwater pumping that significantly diminishes the amount of water available to satisfy the purpose of the reservation. These rulings attribute more expansive water rights to federal claimants than to those asserting claims pursuant only to state law. To explain this aspect of the trial court's decision and to set the context for our discussion, we review some history and terms.
¶ 7 In Gila River II, we summarized the bifurcation of Arizona law respecting surface water and groundwater: [R]ights associated with water found in lakes, ponds, and flowing streamssurface waterhave been governed by the doctrine of prior appropriation.... On the other hand, underground water has been governed by the traditional common law notion that water percolating generally through the soil belongs to the overlying landowner, as limited by the doctrine of reasonable use. [3] 175 Ariz. at 386, 857 P.2d at 1240. ¶ 8 Arizona does not entirely confine the doctrine of prior appropriation to surface waters. Our courts have extended prior appropriation to a category known as subflow, historically defined as those waters which slowly find their way through the sand and gravel constituting the bed of the stream, or the lands under or immediately adjacent to the stream, and are themselves a part of the surface stream. Id. at 387, 857 P.2d at 1241 ( quoting Maricopa County Mun. Water Conserv. Dist. No. 1 v. Southwest Cotton Co., 39 Ariz. 65, 96, 4 P.2d 369, 380 (1931) ( Southwest Cotton )). The notion of subflow is significant in Arizona law, for it serves to mark a zone where water pumped from a well so appreciably diminishes the surface flow of a stream that it should be governed by the same law that governs the stream. Id. at 96-97, 4 P.2d at 380-81. ¶ 9 Yet the notion of subflow is an artifice, as we acknowledged in Gila River II, that rests on a hydrological misconception. 175 Ariz. at 389, 857 P.2d at 1243. To pump well water from lands under or immediately adjacent to a stream is not, we now know, the only pumping that may significantly diminish surface flow. The hydrological connection of groundwater and surface water is sometimes such that groundwater pumped more distantly within an aquifer may have comparable effect. Leshy and Belanger [4] explain: When water is pumped from an aquifer by means of a well, it creates what is known as a cone of depression. This is caused by the groundwater in the aquifer moving toward the well. If the material in the aquifer has a high transmissivity value, the cone of depression will be wide and shallow. If, on the other hand, the aquifer does not easily transmit water, the cone of depression will be steep and narrow. If water is pumped continuously from the well, the cone of depression will become larger. If the water table is close enough to the earth's surface to allow this cone to cut into a surface stream, water from the stream would directly infiltrate into the ground, following the slope of the cone of depression until it reached the well. Even if the cone did not intersect the stream directly, it could affect the amount of water in the stream by intercepting water that would otherwise migrate toward the stream. This would cause less water to be available in the stream bed. If water were removed by pumping from a well and none were reintroduced, the water table would decline. If several wells were pumping, there would be a more rapid decline. Any time the rate of water withdrawn from an aquifer exceeds the rate of recharge, the water table will decline. Leshy & Belanger, 20 Ariz. St. L.J. at 663-64. ¶ 10 Conforming their law to hydrological reality, most prior appropriation jurisdictions by now have abandoned the bifurcated treatment of ground and surface waters and undertaken unitary management of water supplies. Id. at 659-60. In Gila River II, however, we declined to do so, explaining: [I]t is too late to change or overrule [ Southwest Cotton ].... More than six decades have passed since Southwest Cotton was decided. The Arizona legislature has erected statutory frameworks for regulating surface water and groundwater based on Southwest Cotton. Arizona's agricultural, industrial, mining, and urban interests have accommodated themselves to those frameworks. Southwest Cotton has been part of the constant backdrop for vast investments, the founding and growth of towns and cities, and the lives of our people. Gila River II, 175 Ariz. at 389, 857 P.2d at 1243. Limiting ourselves to interpreting Southwest Cotton, not refining, revising, correcting, or improving it, we reaffirm[ed] Southwest Cotton's narrow concept of subflow and directed the trial court to devise a subflow standard on remand that turns on whether the well is pumping water that is more closely associated with the stream than with the surrounding alluvium. Id. at 389-93, 857 P.2d at 1243-47.
¶ 11 A subflow standard, once it has been established, will serve to identify well-users who pump water subject to prior appropriation. But this adjudication is not limited to water subject to prior appropriation; it extends also to water subject to claims based on federal law. An adjudication such as this cannot achieve its comprehensive purpose without quantifying and prioritizing federal, as well as state law, claims. Since there is not enough water to meet everyone's demands, a determination of priorities and a quantification of the water rights accompanying those priorities must be made. Obviously, such a task can be accomplished only in a single proceeding in which all substantial claimants are before the court so that all claims may be examined, priorities determined, and allocations made. See United States v. Super. Ct., 144 Ariz. 265, 270, 697 P.2d 658, 663 (1985). ¶ 12 Approximately two-thirds of the land in Arizona is federally held, much of it in trust for Indian tribes. See ARIZONA STATISTICAL ABSTRACT 173-177 (1993 ed.). The McCarran Amendment permits us to include federal claimants in the adjudication, for it permits the United States to participate in state court proceedings that comprehensively adjudicate rights to the use of water of a river system or other source. 43 U.S.C. § 666(a). In conformity with the McCarran Amendment, our general adjudication statute, A.R.S. § 45-252(A), authorizes determination of the nature, extent and relative priority of the water rights of all persons in the river system and source. And A.R.S. § 45-251(4), as we have indicated, defines river system and source to include not only appropriable water, but all water subject to claims based upon federal law. [5] ¶ 13 The rub is that, in order to adjudicate and quantify water rights based upon federal law, the Arizona courts must afford federal claimants the benefit, when state and federal law conflict, of federal substantive law. See Arizona v. San Carlos Apache Tribe, 463 U.S. 545, 571, 103 S.Ct. 3201, 77 L.Ed.2d 837 (1983) (state courts must apply federal substantive law to measure federal rights in state adjudication); accord United States v. Super. Ct., 144 Ariz. at 276-77, 697 P.2d at 669-70. And the particular issues that we now consider arise pursuant to a doctrine of federal substantive law known variously as the reserved water rights, the reserved rights, or the implied reservation doctrine. ¶ 14 The reserved water rights doctrine provides: [W]hen the Federal Government withdraws its land from the public domain and reserves it for a federal purpose, the Government, by implication, reserves appurtenant water then unappropriated to the extent needed to accomplish the purpose of the reservation. In so doing the United States acquires a reserved right in unappropriated water which vests on the date of the reservation and is superior to the rights of future appropriators. Cappaert v. United States, 426 U.S. 128, 138, 96 S.Ct. 2062, 48 L.Ed.2d 523 (1976). The doctrine applies not only to Indian reservations, but to other federal enclaves, such as national parks, forests, monuments, military bases, and wildlife preserves. Id. at 138-39, 96 S.Ct. 2062; Arizona v. California, 373 U.S. 546, 601, 83 S.Ct. 1468, 10 L.Ed.2d 542 (1963).