Arizona's tracked reservoirs read about 84% full at the start of July 2026 — a number that, taken at face value, would make it one of the wettest states in the Southwest. It is a mirage. That figure is almost entirely two Colorado River reservoirs — Lake Mohave (105%) and Lake Havasu (89%) — that the US Bureau of Reclamation holds near the top by design, because their job is to regulate river flow between the big dams, not to store water for dry years. Strip them out and Arizona's own storage tells a much drier story: San Carlos Reservoir, the largest reservoir wholly inside the state, is essentially empty. And the water Arizona actually lives on — its Colorado River allocation, banked in Lake Mead (26%) and Lake Powell (22%) — sits in two reservoirs that line Arizona's borders but are chronically low. Live figures are on the Arizona page; the national picture is on the United States page.
Key takeaways
- The ~84% headline is misleading. It is dominated by two Colorado River regulating reservoirs, Lake Mohave and Lake Havasu, that Reclamation keeps near full on purpose. They are not a measure of Arizona's water security. Live figures are on the Arizona page.
- In-state storage is far lower. San Carlos — the biggest reservoir entirely within Arizona — is about 0% full, and the Verde River reservoirs are mixed: Bartlett ~70%, Horseshoe ~33%.
- Arizona's real water bank is low. The state's Colorado River supply is stored in Lake Mead (
26%) and Lake Powell (22%) — chronically depleted, and the reason Arizona has faced formal Colorado River shortage cuts. - A flat 105% is the tell. Lake Mohave has read almost exactly 105% every July for five years running. A reservoir that never moves is being operated to a target, not filling and emptying with the weather.
- Our Arizona coverage is partial, and we say so. The Salt River Project reservoirs above Phoenix — Roosevelt and the Salt River chain — are not in the federal real-time feeds we use, so this snapshot leans on the Colorado, Gila and Verde systems.
Where the data comes from — and what it misses
There is no single national US reservoir bulletin, and Arizona shows why the source matters as much as the number. The reservoirs we track here come from federal gauges: the US Bureau of Reclamation for the Colorado River reservoirs (Mohave, Havasu, and Mead and Powell), and the US Geological Survey (USGS) for the Gila and Verde reservoirs (San Carlos, Bartlett, Horseshoe). What is not here is the Salt River Project system — Theodore Roosevelt Lake and the Salt River chain that supplies much of metropolitan Phoenix — because SRP publishes its own data outside the federal real-time APIs we mirror. So treat this as the federally-gauged slice of Arizona, not the whole of it. Every figure is dated; the live numbers and each reservoir's chart are on the Arizona page.
The current picture (as of late June 2026)
Sorted by what the reservoir is for, the Arizona picture separates into three groups.
| Reservoir | River / role | Fill |
|---|---|---|
| Lake Mohave | Colorado — regulating (Davis Dam) | 105% |
| Lake Havasu | Colorado — regulating (Parker Dam) | 89% |
| Bartlett | Verde — storage | 70% |
| Blue Ridge (C.C. Cragin) | East Clear Creek — storage | 58% |
| Horseshoe | Verde — storage | 33% |
| San Carlos | Gila — storage | 0% |
The top two lines carry the state average, and they are the two that mean the least for drought. Lake Mohave and Lake Havasu are "run-of-river" regulating reservoirs behind Davis and Parker dams: their surface is held within a narrow band so they can pass Colorado River water downstream to California, Arizona and Mexico on schedule. They stay near full in wet years and dry years alike. The reservoirs that do rise and fall with Arizona's weather — the Verde and Gila storage reservoirs — are the ones running low, and the largest of them, San Carlos, is empty.
The reservoir that never moves
The clearest evidence that the headline is an operating artefact, not a water-supply signal, is Lake Mohave's history. Here is its early-July fill for five straight years, next to San Carlos on the Gila:
| Reservoir | Jul 2022 | Jul 2023 | Jul 2024 | Jul 2025 | Jul 2026 |
|---|---|---|---|---|---|
| Lake Mohave | 105% | 105% | 105% | 105% | 105% |
| San Carlos | 0% | 53% | 34% | 7% | 0% |
Mohave does not budge — it is held to a target. San Carlos swings wildly, from a wet-year 53% in 2023 back to empty in 2026, because it is a real storage reservoir on a drought-prone river. Averaging the two into a single state percentage buries exactly the information a reader wants.
Arizona's real water bank: Mead and Powell
For most of Arizona, the reservoir that matters is not inside the state at all. Arizona's cities and farms run substantially on Colorado River water delivered through the Central Arizona Project, and that water is stored in the two giant reservoirs on the state's borders: Lake Mead, behind Hoover Dam on the Arizona–Nevada line, and Lake Powell, behind Glen Canyon Dam on the Arizona–Utah line. We track them under Nevada and Utah, but they are Arizona's lifeline — and both are chronically low: Mead is around 26% and Powell around 22% of capacity. Those depleted reservoirs are why Arizona has been in a formally declared Colorado River shortage, taking mandatory cuts to its allocation. The state's Colorado River regulating reservoirs can read 100% while the storage that actually backs its supply reads a quarter full.
What reservoir levels do — and don't — tell you here
- What a reservoir is for changes what its level means. A regulating reservoir at 105% and a storage reservoir at 105% are not the same news: the first is being held there on purpose; the second would be a genuinely wet year. Arizona is the clearest case in the US where you cannot read the number without knowing the reservoir's job.
- Storage is a lagging signal, and a partial one. The Verde and Gila levels reflect the recent run of dry-to-mixed years over central Arizona; they do not forecast the summer monsoon, which is what actually decides whether San Carlos and Horseshoe refill.
- Groundwater is the missing half. Much of Arizona's water, especially for agriculture and some cities, comes from aquifers that no reservoir gauge captures. Full or empty, these reservoirs describe only the surface-water slice of the state's supply.
What it means for the summer
The practical read for 2026: do not be reassured by Arizona's ~84% headline. The two reservoirs holding it up are Colorado River regulators that would read near-full in a drought year too. The reservoirs that track Arizona's own conditions are low — San Carlos empty, the Verde storage reservoirs mixed — and the Colorado River bank the state ultimately depends on, Mead and Powell, remains near its long-term lows. Whether the in-state reservoirs recover this summer rests on the North American monsoon; whether the Colorado stabilises rests on the Rocky Mountain snowpack far upstream. Neither is something a July storage number can predict.
The honest summary: a high state average built almost entirely on two reservoirs that are supposed to be full, sitting over an in-state and Colorado River picture that is much drier than 84% suggests.
FAQ
What are Arizona's reservoir levels right now?
The tracked reservoirs average about 84% of capacity as of late June 2026 — but that is dominated by two Colorado River regulating reservoirs, Lake Mohave (105%) and Lake Havasu (89%), that are kept near full by design. Arizona's own storage is far lower — San Carlos is near 0%. Live figures are on the Arizona page.
Is Arizona in a drought in 2026? Yes, in the ways that matter. Its in-state storage reservoirs are low to empty, and its Colorado River supply in Lake Mead and Lake Powell is near record lows, which has triggered formal shortage cuts to Arizona's allocation. The high average fill is an artefact of two regulating reservoirs, not a sign the drought is over.
Why is Lake Mohave always around 105% full? Because it is a regulating reservoir behind Davis Dam, operated to hold a fairly constant level so it can pass Colorado River water downstream on schedule. It stays near full in wet and dry years alike, so its level says little about drought — unlike a storage reservoir such as San Carlos, which rises and falls with the weather.
Does reservoirs.earth track all of Arizona's reservoirs? Not yet. This snapshot covers the federally-gauged Colorado, Gila and Verde reservoirs. The Salt River Project system above Phoenix — Roosevelt Lake and the Salt River chain — is a major part of the state's supply but is not in the federal real-time feeds we mirror, so it is not included here.
Where does the data come from? The US Bureau of Reclamation for the Colorado River reservoirs (including Mead and Powell) and the US Geological Survey for the Gila and Verde reservoirs, mirrored with multi-year history on reservoirs.earth.
This is a July 2026 snapshot of Arizona; for the national picture and where drought risk actually sits across the US, see the US reservoir levels edition and the neighbouring Texas reservoir levels, July 2026. How US water-data openness ranks is on the Reservoir Transparency Index.