Colorado River basin

Southwestern United States
36.1°N 111.8°W · scale: Regional to international

See this case in context on the case study map.

A large basin supplying water to seven US states, thirty tribes and Mexico, governed by a stack of compacts and agreements. The volume promised in those agreements exceeds what the river reliably carries.

What is changing here, and the mechanisms driving it.

• Over-allocation established by historic agreement
• Reduced snowpack and runoff
• Reservoir drawdown at Powell and Mead
• Administrative shortage sharing between states

Find these, and write the year beside every figure. A statistic without a date is not evidence.

• Reservoir elevations at Lake Mead and Lake Powell, dated
• Volumes allocated versus average annual flow
• Size of the cuts imposed on each state
• Share of basin water used by agriculture

Who is affected, and separately, who holds the decision-making power.

• Agricultural users holding senior water rights
• Cities including Phoenix, Las Vegas and Los Angeles
• Thirty federally recognised tribes
• Mexico, under the 1944 treaty

Named above as a starting list. For each one, add what they actually want, and note where two of them want incompatible things.

Find two sources that disagree about this case — not two summaries of the same view. Record who each is, what they claim, and what interest they have. A perspective without a holder is not a perspective.

Which of the six apply here, and what each one reveals.

• Power. When users could not agree, the federal government decided.
• Scale. Municipal restriction to international treaty, one river.
• Possibility. Reallocation, efficiency and reduced demand — each with different losers.

How significant is this? How effective was any response? What are the limitations of your evidence? What else could explain the pattern? Reach a judgement and defend it.

One dated development from the last twelve months. Does it strengthen, weaken or complicate the case as recorded above? Update this every time you revisit the case.

Water scarcity, competing demands, and the politics of allocation.

• Bureau of Reclamation — Post-2026 Operations usbr.gov
  The primary source. Decision documents, the Record of Decision, and the operating guidelines.
• Geography in the News — the 2026 framework
  On this site: what was decided, who absorbs the cuts, and why the states failed to agree.
• Drought.gov drought.gov
  Current drought status, reservoir conditions and seasonal outlooks.