THE CRISIS / EXPLAINER
Where the water goes
About 19.3 maf of water leaves the Colorado River every year before what is left reaches its delta. 52 percent of it grows crops, and most of that grows hay for cattle; cities and industry take 18 percent; rivers and wetlands transpire 19 percent and the reservoirs evaporate 11 percent. Follow the water from where it is used to what it is used for to which crops.
The diagram
The whole river, all water consumed: 19.3 maf a year
Where it is used
- Upper Basin 31%
- Lower Basin 51%
- Gila Basin 9%
- Mexico 8%
What it is used for
- Agriculture 52%
- Cities & industry 18%
- Rivers & wetlands 19%
- Reservoir evaporation 11%
Which crops
- Alfalfa 27%
- Other hay 6%
- Wheat 6%
- Cotton 3%
- Corn 1%
- Other crops 10%
| Use | Upper Basin | Lower Basin | Gila Basin | Mexico | Total |
|---|---|---|---|---|---|
| Agriculture | 3512.96 | 6610.06 | 725.55 | 1598.83 | 12447 |
| Cities & industry | 974.49 | 2621.70 | 522.52 | 252.28 | 4371 |
| Rivers & wetlands | 1757.32 | 1752.74 | 742.52 | 149.51 | 4402 |
| Reservoir evaporation | 1139.67 | 1234.65 | 154.19 | 0.00 | 2529 |
| of agriculture: Alfalfa | 2213.63 | 3347.01 | 391.80 | 415.70 | 6368.14 |
| of agriculture: Other hay | 932.96 | 542.59 | 21.77 | 15.99 | 1513.31 |
| of agriculture: Wheat | 75.59 | 396.60 | 58.04 | 799.42 | 1329.65 |
| of agriculture: Cotton | 0.00 | 251.65 | 181.39 | 287.79 | 720.83 |
| of agriculture: Corn | 204.52 | 13.56 | 21.77 | 0.00 | 239.85 |
| of agriculture: Other crops | 86.26 | 2058.65 | 50.78 | 79.93 | 2275.62 |
| Total | 7384.44 | 12219.15 | 2144.78 | 2001 | 23749 |
How to read this
The left column is where the water is used: the Upper Basin above Lee Ferry, the Lower Basin below it, the Gila Basin that joins near Yuma, and Mexico, each including the water its canals and pipelines export to cities outside the basin (about 12 percent of the river, to the Front Range, Utah's Wasatch Front, Albuquerque, coastal Southern California and Tijuana). The middle column is what it is used for. The right column splits agriculture into crops; “Other crops” is the remainder so the crops add up to agriculture exactly. “All water” counts everything the river loses on its way to the delta; “Direct use only” counts what people take, 13.4 maf a year, on which farms read 75 percent and cities 25 percent. Hover or focus a node to follow its water; click or press Enter to pin it; the basin chips re-base every share to one unit.
Why the river no longer reaches the sea
- The river matters to more than 40 million people and more than 2 million hectares of cropland, in seven states, 30 tribal nations and Mexico.
- It was overconsumed, with more taken than flowed in, in 16 of 21 years from 2000 to 2020, an average overdraft of 10 percent a year, drawn from Lake Mead and Lake Powell.
- Stabilising the reservoirs would take cuts of 2.4 to 3.2 million acre-feet a year, 22 to 29 percent of direct use in the two basins, and likely another 811 thousand to 2.4 million acre-feet by 2050 as warming reduces runoff.
- The Lower Basin is already using less: cities and industry consumed 38 percent less in 2019 than in 2000, and farms 15 percent less.
What this diagram does not show
No split of cities into homes, businesses and industry: the delivery data behind the accounting does not separate them, and nothing unsourced is drawn. No “tribal” sector: tribal water is used for farms and for towns and is counted inside those sectors; who holds the senior rights is the subject of how water rights work. The four units are drawn as a schematic, not a map. Every figure is a cell in the paper's two tables, and the site refuses to build if they stop adding up.
Sources
Every number on this page is read from one of these documents, at the place named. The tables are 2000–2019 averages in million cubic metres a year; one million acre-feet is 1,233.48 of them.
- New water accounting reveals why the Colorado River no longer reaches the sea · Richter, B. D., Lamsal, G., Marston, L., Dhakal, S., Sangha, L. S., Rushforth, R. R., Wei, D., Ruddell, B. L., Davis, K. F., Hernandez-Cruz, A., Sandoval-Solis, S. and Schmidt, J. C.; Communications Earth & Environment 5:134 (open access; full text also at par.nsf.gov/servlets/purl/10511760), 2024-03-28.Table 1 (p. 4): all water consumed by unit, sector and crop; Table 2 (p. 5): direct human uses; pp. 1 and 3: people, cropland, tribal nations, overconsumption and exports; p. 3: cattle-feed shares; p. 6: Lower Basin declines; p. 8: the cuts needed to stabilise the reservoirs.
- 2027–2028 Operating Guidelines: Colorado River Guidelines for Coordinated Operations of Lake Powell and Lake Mead · Department of the Interior, Bureau of Reclamation, 2026-08-21.Section 5.3, pp. 8–9: reductions of 760,000 af (Arizona), 440,000 af (California), 50,000 af (Nevada) and 700,000 af of system conservation.