Wyoming v. Colorado
The Court issued a final decree in a water dispute between Colorado and Wyoming, limiting how much water Colorado could divert from the Laramie River through a specific tunnel project while protecting certain existing Colorado water rights up to fixed amounts.
The decree set exact yearly limits in acre-feet for several competing water uses, resolving a long-running interstate fight over a shared river and giving both states a clear allocation to follow going forward.
How it got here: Wyoming sued Colorado directly in the Supreme Court's original jurisdiction over shared river water rights, and commissioners took evidence before the Court issued this decree.
The Case in Depth
What happened
Wyoming sued Colorado in a dispute over rights to the Laramie River, a stream that crosses the state line. Colorado water users had built projects, including the Laramie-Poudre Tunnel, the Skyline Ditch, and various meadow-land irrigation works, to divert water from the river and its tributaries, and Wyoming argued these diversions were taking more water than Colorado was entitled to.
The question before the Court
How much water could Colorado's water users keep taking from the Laramie River without violating Wyoming's rights downstream?
Why it matters
Farmers, ranchers, and water officials in both Colorado and Wyoming who depend on the Laramie River now have specific, enforceable limits on how much water can be diverted for particular projects. This kind of court-ordered allocation shapes water planning and irrigation for decades, since river water is a scarce and contested resource in the arid West.
What changes now
The decree fixed firm yearly limits on Colorado's Laramie-Poudre Tunnel diversions while leaving other named Colorado appropriations undisturbed, and ordered Colorado to pay Wyoming's litigation costs. A footnote notes that a modified decree was later entered on October 9, 1922, meaning this initial decree was not the final word on the exact allocation between the two states.
What this does not decide
The decree does not resolve rights to Sand Creek, leaving both states free to continue any lawful existing diversions there. It also does not permanently fix the numbers stated here, since the opinion notes a modified decree was later issued in 1922.
How the Court got there
The legal reasoning, step by step
- The Court had already taken evidence through commissioners appointed to examine the facts of how much water each side's projects used and needed.
- Applying the interstate doctrine of equitable apportionment, under which the Court divides a shared river's water fairly between states based on existing beneficial uses, the Court set specific caps on the newer Laramie-Poudre Tunnel diversion.
- The Court preserved, rather than disturbed, the water amounts already being used under older, previously recognized Colorado appropriations, including the Skyline Ditch and the meadow-land projects.
- The Court also carved out Sand Creek, leaving each state free to continue any lawful existing diversions from that tributary without the decree affecting those rights.