Who Drinks the River?
The Colorado's paper allocations exceed its water, and the shortfall has to land on someone. This is a working model of that arithmetic: set the river's flow, choose the allocation rule, and the model computes who gets what.
Reservoir storage, next 30 years
Who takes the cut
What this is. An annual mass balance of the Colorado mainstem: one storage node (Mead+Powell), naturalized Lees Ferry inflow, direct human consumption held at its 2000–2019 recorded average (13.7 MAF/yr), evaporation scaling with storage. Backtested against the 2000–2024 reservoir collapse; its one calibrated parameter (1.77 MAF/yr of residual inflow) sits inside the hydrologically expected range.
Stylization. The seniority rule shown here is a party-level simplification of the priority system — Arizona's CAP is junior to California's 4.4 MAF under the 1968 Basin Project Act, so cuts stack Arizona → Nevada → Mexico → California. Real law operates on individual rights and treaty minutes. The 2027–28 rule follows the Record of Decision signed August 21, 2026: the states' own negotiated split for the first 1.5 MAF, seniority beyond it.
Sources. Richter et al. 2024, 10.1038/s43247-024-01291-0 (consumption accounting); Reclamation natural-flow database 1906–2024 (supply); Boulder Canyon Project Act & 1944 Treaty (entitlements); post-2026 ROD (framework). Full verification ledger ships with the source.