Reservoirs
Below normalWestern reservoir levels, total storage
34.21M af across the 21 major western reservoirs The Waterline tracks, as of Sep 30, 2026 (40% of combined capacity). One combined daily storage total.
Data through Sep 30, 2026 · source last checked Oct 8, 2026 · page revised Oct 8, 2026
Cite
- Total storage
About this data
- Source
- US Bureau of Reclamation RISE; California reservoirs via CA DWR CDEC
- Series
- End-of-day reservoir storage
- Geography
- Western reservoir levels, total
- Unit
- acre-feet
- Calculation
- Daily reading
- Last observation
- Sep 30, 2026
- Update frequency
- Daily
Now 34.21M af, 11% below the 5-yr median, 40% of combined capacity.
Total storage across the 21 major western reservoirs stood at 34.21M af as of Sep 30, down 11.4% year over year. The level sits 11% below the 5-year median at 40% of combined capacity. Month over month storage fell 3.0%, with a week-over-week change of -0.4%.
| Period | Current | Prior | Change |
|---|---|---|---|
| Week over week | 34.21M af | 34.34M af | -0.4% |
| Month over month | 34.21M af | 35.26M af | -3.0% |
| Year over year | 34.21M af | 38.61M af | -11.4% |
| vs 5-yr median | 34.21M af | 38.61M af | -11.4% |
| Basin | Reservoirs | Storage | Share of capacity | vs 5-yr median | As of |
|---|---|---|---|---|---|
| Gunnison-Colorado | Blue Mesa Reservoir | 142,964 af | 15% | -65% | Oct 7, 2026 |
| Colorado (Upper) | Lake Powell | 5.21M af | 21% | -28% | Oct 7, 2026 |
| Rio Grande | Elephant Butte Reservoir | 87,311 af | 4% | -23% | Oct 7, 2026 |
| Wind-Bighorn-Missouri | Boysen Reservoir | 496,296 af | 67% | -21% | Oct 7, 2026 |
| Colorado (Lower) | Lake Havasu, Lake Mead, Lake Mohave | 8.96M af | 31% | -17% | Oct 7, 2026 |
| Green-Colorado | Flaming Gorge Reservoir, Fontenelle Reservoir | 2.75M af | 68% | -15% | Oct 7, 2026 |
| Feather-Sacramento | Lake Oroville | 1.56M af | 46% | -15% | Oct 7, 2026 |
| Sacramento | Shasta Lake, Whiskeytown Lake | 2.65M af | 55% | -8% | Oct 7, 2026 |
| San Juan-Colorado | Navajo Reservoir | 839,028 af | 49% | -7% | Oct 7, 2026 |
| San Joaquin | Millerton Lake, New Melones Lake | 1.75M af | 60% | -6% | Oct 7, 2026 |
| American-Sacramento | Folsom Lake | 416,720 af | 43% | -6% | Oct 7, 2026 |
| Flathead-Columbia | Hungry Horse Reservoir | 3.11M af | 90% | -2% | Sep 30, 2026 |
| Missouri | Canyon Ferry Lake | 1.49M af | 79% | +1% | Oct 7, 2026 |
| Tuolumne-San Joaquin | New Don Pedro Reservoir | 1.52M af | 75% | +1% | Oct 6, 2026 |
| Trinity-Klamath | Trinity Lake | 1.67M af | 68% | +32% | Oct 7, 2026 |
| San Joaquin-Delta | San Luis Reservoir | 1.49M af | 73% | +42% | Oct 7, 2026 |
A basin with more than one tracked reservoir is summed on the days every one of them reports, then compared with the same sum's median for the date over up to five prior years. Share of capacity uses each reservoir's total capacity.
Previous weeks
Week of Sep 23, 2026
Western storage totaled 34.34M af as of Sep 23, down 11.6% from a year earlier. At 40% of combined capacity, the 21-reservoir total sat 12% below its 5-year median.
An earlier week
Total storage across the 20 major western reservoirs is 32.95M af, down 13% from a year ago and 13% below the 5-year median. The system lost 4.6% month-to-month, with week-to-week essentially flat. Reservoirs stand at 39% of combined capacity.
Week of Sep 14, 2026
Storage across the 20 major western reservoirs totaled 33.21M af on Sep 14, running 13% below the 5-year median at 39% of combined capacity. Year-over-year storage fell 12.9%. The month-over-month decline was 5.4%.
Week of Sep 1, 2026
Total storage across the 20 major western reservoirs stands at 33.92M af as of Sep 1, down 12.5% from a year ago. Storage sits 13% below the 5-year median. The pool shed 1.3% over the week.
About this total
The 21 major western reservoirs The Waterline tracks hold 34.21 million acre-feet combined as of Sep 30, 2026, 40% of combined capacity and 11% below the 5-yr median. Measured against its own capacity, Elephant Butte Reservoir is the emptiest at 4% and Whiskeytown Lake the fullest at 98%.
This page adds up the reservoir levels The Waterline tracks, 21 of the West's major reservoirs including Lake Mead, Lake Powell, Hungry Horse Reservoir, Flaming Gorge Reservoir, into one combined daily storage total. It is the widest single read on how much water the tracked system is holding, compared to its own five-year median like every other page on the site. A day appears here only when every tracked reservoir reports it, so the total is always a true sum of the same set and a gap in one reservoir's feed never shows up as a system-wide swing. It is the total for this tracked set, not for every reservoir in the West: use it for the direction and scale of the system, the storage by basin table for the river systems behind a move, and the per-reservoir pages for the specific projects.
Common questions
What are Western reservoir levels right now?
The 21 major western reservoirs The Waterline tracks hold 34.21M af combined as of Sep 30, 2026, 40% of combined capacity, 11% below the 5-yr median. The chart above carries the daily total, and the per-reservoir pages carry each project's own level.
Are reservoir levels rising or falling?
Tracked-total storage is falling right now, and has fallen 25 consecutive weeks. The system is in the summer-fall drawdown, when irrigation and delivery releases typically exceed inflow.
Which reservoirs does this total cover?
The 21 major western reservoirs on this site, including Lake Mead, Lake Powell, Hungry Horse Reservoir, Flaming Gorge Reservoir. It is the total for this tracked set, not for every reservoir in the West, and a day appears in the total only when every member reports it. The reservoir section lists each one.
Where does this data come from?
Daily end-of-day storage readings from the US Bureau of Reclamation's RISE system, with California reservoirs from the state's CDEC network (CA DWR). The methodology page has the full sourcing.