added). Plaintiffs point out, correctly, that beneficial use is an evolving and dynamic requirement of federal and state law. See Joslin v. Marin Mun. Water Dist., 67 Cal.2d 132, 140, 60 Cal.Rptr. 377, 429 P.2d 889 (1967) (While “what is a reasonable use of water depends on the circumstances of each case, such an inquiry cannot be resolved in vacuo isolated from statewide considerations of transcendent importance.”). Section 8 of the Reclamation Act of 1902 requires that all water provided pursuant to the Act be put to “beneficial use,” as defined by state law. 43 U.S.C. §§ 372, 383; California v. United States, 438 U.S. 645, 665-67, 98 S.Ct. 2985, 57 L.Ed.2d 1018 (1978); see also City of Barstow v. Mojave Water Agency, 23 Cal.4th 1224, 1242, 99 Cal.Rptr.2d 294, 5 P.3d 853 (2000) (<HOLDING>); United States v. Alpine Land & Reservoir Co.,
holding that article x  2 of the california constitution dictates the basic principles defining water rights that no one can have a protectible interest in the unreasonable use of water and that holders of water rights must use water reasonably and beneficially holding that mandamus was appropriate to require the director to deliver the full decreed water rights of a water right holder holding that the montana constitution protects water rights against unreasonable state action  holding substantial completion had occurred because water district took possession of all the lines filled them with water and began using them to serve the customers of the water district recognizing that water rights constitute a real property interest