Surface water
The Colorado River Is Over-Allocated
The Colorado River is over-allocated. Legal entitlements total 16.5 million acre-feet a year, while actual average flow is about 12.5 MAF — a structural deficit of roughly 4.6 MAF, or about 28% of everything promised on paper. That gap exists today, before any additional warming, because the 1922 Compact divided a flow record measured during an unusually wet stretch. Flow has fallen roughly 20% since 2000, and about 40 million people depend on the river.
The structural deficit
| Legal allocation | 16.5 MAF/yr | What the Compact and treaties promise |
|---|---|---|
| Actual average flow | 12.5 MAF/yr | What the river actually delivers |
| Structural deficit | 4.6 MAF/yr | About 28% of allocations have no water behind them |
| Flow decline since 2000 | ~20% | Measured against the 20th-century baseline |
| People dependent | 40M | Across seven US states and Mexico |
| Basin area | 246,000 sq mi | River length 1,450 miles |
Why an over-allocated river matters to groundwater
When surface allocations cannot be met, the shortfall does not disappear — it is made up by pumping. That is the mechanism connecting a Colorado River shortage to falling water tables hundreds of miles away: every acre-foot not delivered from the river becomes an acre-foot drawn from an aquifer that recharges far more slowly than it is being emptied.
It is also why storage, rather than allocation reform alone, changes the arithmetic. A river running 20% below its baseline still produces flood peaks. Capturing those peaks underground is the difference between a wet year passing through and a wet year being banked. How aquifer storage and recovery does that →
Lake Mead reference points
Lake Mead is the buffer absorbing the deficit. Its elevation moves constantly, so the figure below is a dataset reference point rather than a live reading — but the thresholds around it are fixed and are what matter.
Pre-drought (2000)
1,214 ft
Dataset reference
1,065.37 ft
Minimum power generation
1,050 ft
Dead pool
895 ft
At the dataset reference elevation the lake sits about 149 ft below its pre-drought level and roughly 170 ft above dead pool — the point at which water can no longer pass the dam. Power generation becomes unreliable at 1,050 ft, which is reached well before dead pool. For current elevation, consult the US Bureau of Reclamation directly; this page is about the structural gap, which does not move with the weather.