Reservoir Watch
Official storage levels across 498 reservoirs in 36 states. Data from the US Bureau of Reclamation.
Average fill
59%
Total volume
169.5 km³
Reservoirs
498
Critical
50
Low level
82
Fill by state
Hover for details · USBR coverageLoading map…
US at a glance
National average fill
59%
169,489 of 287,497 hm³ stored
Reservoirs
498
States
36
Total capacity
287.5 km³
Volume stored
169.5 km³
Critical
50
Low level
82
Coverage: USBR (Bureau of Reclamation) reservoirs — primarily 17 western states. Eastern US reservoirs managed by USACE are not yet included. Last reading: 2026-07-31.
National fill — multi-year
By state
Sorted by capacityUtah
27 reservoirs
Average fill
31.1%
Nevada
7 reservoirs
Average fill
28.1%
California
33 reservoirs
Average fill
70.3%
South Dakota
14 reservoirs
Average fill
81.6%
Oklahoma
54 reservoirs
Average fill
77.6%
Texas
29 reservoirs
Average fill
66.0%
Montana
20 reservoirs
Average fill
86.3%
Wyoming
25 reservoirs
Average fill
49.4%
Kansas
31 reservoirs
Average fill
64.8%
Louisiana
3 reservoirs
Average fill
72.8%
Idaho
20 reservoirs
Average fill
42.0%
Missouri
6 reservoirs
Average fill
27.6%
New Mexico
16 reservoirs
Average fill
24.5%
Arizona
7 reservoirs
Average fill
83.7%
Colorado
40 reservoirs
Average fill
53.5%
Tennessee
6 reservoirs
Average fill
92.6%
Washington
16 reservoirs
Average fill
51.2%
Georgia
4 reservoirs
Average fill
96.0%
Oregon
24 reservoirs
Average fill
28.3%
Arkansas
1 reservoir
Average fill
94.5%
New York
7 reservoirs
Average fill
90.7%
Virginia
4 reservoirs
Average fill
83.6%
Massachusetts
2 reservoirs
Average fill
83.4%
Alabama
5 reservoirs
Average fill
90.2%
Minnesota
6 reservoirs
Average fill
76.8%
Pennsylvania
13 reservoirs
Average fill
75.0%
Ohio
22 reservoirs
Average fill
67.1%
Indiana
6 reservoirs
Average fill
82.9%
Nebraska
18 reservoirs
Average fill
55.9%
Mississippi
2 reservoirs
Average fill
50.7%
North Dakota
8 reservoirs
Average fill
74.5%
West Virginia
9 reservoirs
Average fill
79.7%
Iowa
3 reservoirs
Average fill
87.8%
Illinois
4 reservoirs
Average fill
84.2%
Kentucky
6 reservoirs
Average fill
111.9%
South Carolina
0 reservoirs
Average fill
0.0%
All reservoirs
Click a pin to exploreLoading map…
States shown as N/A
Alaska, Connecticut, Delaware, District of Columbia, Hawaii, Maine, Maryland, Michigan, New Hampshire, New Jersey, Puerto Rico, Rhode Island and Vermont have no reservoirs in the federal datasets we use — USGS NWIS, the Bureau of Reclamation (RISE) and USACE — which cover primarily the 17 western Reclamation states. Eastern, coastal and non-contiguous states are mostly managed by state agencies or USACE districts without a public storage API, so they appear as N/A on the map. We're adding sources as they become available.
Dataset coverage
Tracked
512
reservoirs
With data
512
reservoirs
Tracked capacity
293,190
hm³
Source: USGS NWIS · USACE CWMS · Bureau of Reclamation RISE · CDEC (California)
Federal systems track a subset of US reservoirs. Many state-managed and smaller reservoirs have no public machine-readable storage data. The US has thousands of reservoirs beyond those covered here.
About reservoirs in United States
As of July 31, 2026, the reservoirs we track across United States that report live levels hold roughly 169,489 hm³ of water — about 59.0% of their combined capacity. Taken together, United States's reservoirs are within their normal operating range.
Across the region, 50 reservoirs are at critically low levels and 82 are low. LAKE MOHAVE AT DAVIS DAM, AZ-NV is the fullest at 105.0%, while MUD MOUNTAIN LAKE NEAR BUCKLEY, WA is the lowest at 0.0%.
Over the most recent week on record, 7 reservoirs rose and 9 reservoirs fell across United States.
Storage figures for United States come from USGS · USACE · BOR · CDEC; the most recent reading is from July 31, 2026. Each reservoir below links to its own page with full history and seasonal context.
United States at a glance
- Reservoirs tracked
- 512
- Average fill
- 59.0%
- Water stored
- 169,489 hm³
- Combined capacity
- 293,190 hm³
- At critically low levels
- 50
- Fullest
- LAKE MOHAVE AT DAVIS DAM, AZ-NV (105.0%)
- Lowest
- MUD MOUNTAIN LAKE NEAR BUCKLEY, WA (0.0%)
- Last updated
- July 31, 2026
Frequently asked questions
How full are reservoirs in United States right now?
As of July 31, 2026, the reservoirs tracked in United States that report live levels are 59.0% full overall, holding about 169,489 hm³ of water.
How many reservoirs are there in United States?
reservoirs.earth tracks 512 reservoirs in United States, with a combined storage capacity of 293,190 hm³.
Which reservoir in United States is the fullest?
LAKE MOHAVE AT DAVIS DAM, AZ-NV is currently the fullest reservoir in United States, at 105.0% of capacity.
Which reservoir in United States is the lowest?
MUD MOUNTAIN LAKE NEAR BUCKLEY, WA is currently the lowest in United States, at 0.0% of capacity.
Where does the reservoir data for United States come from?
All storage figures for United States come from USGS · USACE · BOR · CDEC, an official source, last updated July 31, 2026.