United States36 states · USBR official data

Reservoir Watch

Official storage levels across 515 reservoirs in 36 states. Data from the US Bureau of Reclamation.

Average fill

62%

Total volume

212.2 km³

Reservoirs

515

Critical

Low level

Fill by state

Hover for details · USBR coverage

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Status:Critical (<20%)Low (20–40%)Normal / High (>40%)States without color = no USBR reservoirs

US at a glance

National average fill

62%

212,175 of 342,465 hm³ stored

Reservoirs

515

States

Total capacity

342.5 km³

Volume stored

212.2 km³

Critical

Low level

Coverage: USBR (Bureau of Reclamation) reservoirs — primarily 17 western states. Eastern US reservoirs managed by USACE are not yet included. Last reading: 2026-07-27.

National fill — multi-year

By state

Sorted by capacity

Utah

27 reservoirs

Low

Average fill

31.2%

12,134 hm³ storedView →

Nevada

7 reservoirs

Low

Average fill

28.1%

10,451 hm³ storedView →

Montana

24 reservoirs

Average fill

84.9%

29,325 hm³ storedView →

California

33 reservoirs

Average fill

71.6%

24,410 hm³ storedView →

South Dakota

14 reservoirs

Average fill

82.0%

26,647 hm³ storedView →

North Dakota

11 reservoirs

Average fill

80.0%

19,194 hm³ storedView →

Oklahoma

56 reservoirs

Average fill

78.1%

15,454 hm³ storedView →

Texas

29 reservoirs

Average fill

66.2%

12,327 hm³ storedView →

Kentucky

12 reservoirs

Average fill

67.0%

10,081 hm³ storedView →

Wyoming

25 reservoirs

Average fill

50.8%

5,066 hm³ storedView →

Missouri

7 reservoirs

Low

Average fill

39.1%

3,214 hm³ storedView →

Kansas

31 reservoirs

Average fill

64.2%

5,127 hm³ storedView →

Louisiana

3 reservoirs

Average fill

73.5%

5,272 hm³ storedView →

Idaho

20 reservoirs

Average fill

43.6%

3,115 hm³ storedView →

New Mexico

16 reservoirs

Low

Average fill

24.7%

1,549 hm³ storedView →

Arizona

7 reservoirs

Average fill

84.3%

5,188 hm³ storedView →

Colorado

40 reservoirs

Average fill

54.3%

2,683 hm³ storedView →

Tennessee

6 reservoirs

Average fill

94.0%

4,415 hm³ storedView →

Washington

16 reservoirs

Average fill

52.6%

2,200 hm³ storedView →

Mississippi

5 reservoirs

Average fill

51.0%

1,661 hm³ storedView →

Oregon

24 reservoirs

Low

Average fill

29.5%

894 hm³ storedView →

New York

8 reservoirs

Average fill

84.2%

1,842 hm³ storedView →

Virginia

4 reservoirs

Average fill

84.8%

1,760 hm³ storedView →

Massachusetts

2 reservoirs

Average fill

83.4%

1,506 hm³ storedView →

Nebraska

26 reservoirs

Average fill

57.6%

909 hm³ storedView →

Minnesota

6 reservoirs

Average fill

76.8%

1,179 hm³ storedView →

Pennsylvania

13 reservoirs

Average fill

73.6%

1,122 hm³ storedView →

Ohio

26 reservoirs

Average fill

66.7%

988 hm³ storedView →

Alabama

2 reservoirs

Average fill

90.4%

1,061 hm³ storedView →

West Virginia

9 reservoirs

Average fill

84.7%

653 hm³ storedView →

Iowa

3 reservoirs

Average fill

103.1%

370 hm³ storedView →

North Carolina

2 reservoirs

Average fill

96.3%

304 hm³ storedView →

Indiana

1 reservoir

Average fill

91.6%

69 hm³ storedView →

Georgia

0 reservoirs

Critical

Average fill

0.0%

0 hm³ storedView →

South Carolina

0 reservoirs

Critical

Average fill

0.0%

0 hm³ storedView →

Wisconsin

0 reservoirs

Critical

Average fill

0.0%

0 hm³ storedView →

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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

58%of national storage capacity has public data

Tracked

533

reservoirs

With data

533

reservoirs

Tracked capacity

349,800

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 27, 2026, the reservoirs we track across United States that report live levels hold roughly 212,175 hm³ of water — about 62.0% of their combined capacity. Taken together, United States's reservoirs are within their normal operating range.

Across the region, 57 reservoirs are at critically low levels and 77 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 12 reservoirs fell across United States.

Storage figures for United States come from USGS · USACE · BOR · CDEC; the most recent reading is from July 27, 2026. Each reservoir below links to its own page with full history and seasonal context.

United States at a glance

Reservoirs tracked: 533
Average fill: 62.0%
Water stored: 212,175 hm³
Combined capacity: 349,800 hm³
At critically low levels: 57
Fullest: LAKE MOHAVE AT DAVIS DAM, AZ-NV (105.0%)
Lowest: MUD MOUNTAIN LAKE NEAR BUCKLEY, WA (0.0%)
Last updated: July 27, 2026

Frequently asked questions

How full are reservoirs in United States right now?

As of July 27, 2026, the reservoirs tracked in United States that report live levels are 62.0% full overall, holding about 212,175 hm³ of water.

How many reservoirs are there in United States?

reservoirs.earth tracks 533 reservoirs in United States, with a combined storage capacity of 349,800 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 27, 2026.