Arizona v. California
The Court adopted a supplemental decree updating water rights for the Fort Mojave and Colorado River Indian Reservations along the Colorado River, after no one objected to the Special Master's proposed terms.
The order revises long-standing water allocation figures first set in 1964 and later supplemented in 1979 and 1984, fixing new acreage and diversion limits while leaving the rest of the original decree intact.
How it got here: The Special Master proposed a supplemental decree implementing the parties' settlement; the Court published it for objections, none were filed, and it now formally adopts the decree.
The Case in Depth
What happened
This case is a decades-long dispute over how Colorado River water is divided among Arizona, California, Nevada, and several Indian reservations, originally decided by the Supreme Court in 1964. The Fort Mojave and Colorado River Indian Reservations later reached agreements adjusting their boundaries and water entitlements, which required updating the Court's original decree to reflect new acreage and diversion figures.
The question before the Court
Should the Supreme Court formally adopt the Special Master's proposed update to water allocations for two Colorado River tribes?
Why it matters
This order sets the specific amount of Colorado River water two tribal reservations can draw each year, which affects tribal agriculture, water planning for the broader Colorado River basin, and how much water remains available to other users in Arizona, California, and Nevada under the river's long-running allocation system.
What changes now
The updated water allocation figures for the Fort Mojave and Colorado River Indian Reservations take effect immediately as part of the Court's ongoing decree governing Colorado River water rights. The Court retains jurisdiction over the case and may enter further supplemental decrees if future disputes or agreements require additional adjustments to the water allocation scheme.
How the Court got there
The legal reasoning, step by step
- The Special Master, an officer appointed to manage the technical details of this long-running water rights case, drafted a proposed supplemental decree reflecting agreements reached by the parties over the reservations' boundaries and water entitlements.
- The Court had already published the proposed decree as an appendix to its June 2000 opinion and invited any party to file objections with the Clerk.
- Because no objections were filed, the Court treated the absence of dispute as sufficient basis to adopt the Special Master's proposed terms without further proceedings.
- The Court amended the specific numerical provisions of its 1964 decree and 1979 supplemental decree governing acreage, diversion limits, and priority dates for the two reservations, while leaving all other provisions of the prior decrees in force.