Reservoirs
Below normalWestern reservoir levels, total storage
34.34M af across the 21 major western reservoirs The Waterline tracks, as of Sep 23, 2026 (40% of combined capacity). One combined daily storage total.
Data through Sep 23, 2026 · source last checked Oct 1, 2026 · page revised Oct 1, 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 23, 2026
- Update frequency
- Daily
Now 34.34M af, 12% below the 5-yr median, 40% of combined capacity.
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.
| Period | Current | Prior | Change |
|---|---|---|---|
| Week over week | 34.34M af | 34.51M af | -0.5% |
| Month over month | 34.34M af | 35.69M af | -3.8% |
| Year over year | 34.34M af | 38.84M af | -11.6% |
| vs 5-yr median | 34.34M af | 38.84M af | -11.6% |
| Basin | Reservoirs | Storage | Share of capacity | vs 5-yr median | As of |
|---|---|---|---|---|---|
| Rio Grande | Elephant Butte Reservoir | 31,826 af | 2% | -71% | Sep 23, 2026 |
| Gunnison-Colorado | Blue Mesa Reservoir | 144,461 af | 15% | -66% | Sep 23, 2026 |
| Colorado (Upper) | Lake Powell | 5.13M af | 21% | -30% | Sep 23, 2026 |
| Wind-Bighorn-Missouri | Boysen Reservoir | 492,554 af | 66% | -23% | Sep 23, 2026 |
| San Juan-Colorado | Navajo Reservoir | 787,623 af | 46% | -18% | Sep 23, 2026 |
| Colorado (Lower) | Lake Havasu, Lake Mead, Lake Mohave | 9M af | 32% | -17% | Sep 23, 2026 |
| Green-Colorado | Flaming Gorge Reservoir, Fontenelle Reservoir | 2.79M af | 70% | -14% | Sep 23, 2026 |
| Feather-Sacramento | Lake Oroville | 1.63M af | 48% | -14% | Sep 30, 2026 |
| Sacramento | Shasta Lake, Whiskeytown Lake | 2.72M af | 57% | -8% | Sep 23, 2026 |
| San Joaquin | Millerton Lake, New Melones Lake | 1.77M af | 61% | -6% | Sep 23, 2026 |
| American-Sacramento | Folsom Lake | 433,496 af | 44% | -4% | Sep 23, 2026 |
| Flathead-Columbia | Hungry Horse Reservoir | 3.15M af | 91% | -2% | Sep 23, 2026 |
| Missouri | Canyon Ferry Lake | 1.51M af | 80% | 0% | Sep 23, 2026 |
| Tuolumne-San Joaquin | New Don Pedro Reservoir | 1.53M af | 75% | 0% | Sep 29, 2026 |
| Trinity-Klamath | Trinity Lake | 1.70M af | 69% | +32% | Sep 23, 2026 |
| San Joaquin-Delta | San Luis Reservoir | 1.47M af | 72% | +45% | Sep 30, 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
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.
Week of Aug 25, 2026
Combined storage across the 20 major western reservoirs tracked reached 34.37M af on Aug 25, 12% below the 5-year median for this period. Storage fell 1.5% on the week and 6.4% on the month, now at 41% of combined capacity.
About this total
The 21 major western reservoirs The Waterline tracks hold 34.34 million acre-feet combined as of Sep 23, 2026, 40% of combined capacity and 12% below the 5-yr median. Measured against its own capacity, Elephant Butte Reservoir is the emptiest at 2% 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 34.34M af combined as of Sep 23, 2026, 40% of combined capacity, 12% 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 24 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.