United States37 states · USBR official data

Reservoir Watch

Official storage levels across 524 reservoirs in 37 states. Data from the US Bureau of Reclamation.

Average fill

56.8%

Total volume

198.0 km³

Reservoirs

524

Critical

Low level

Fill by state

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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

56.8%

197,984 of 348,756 hm³ stored

Reservoirs

524

States

Total capacity

348.8 km³

Volume stored

198.0 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: 2026-09-10.

National fill — multi-year

By state

Sorted by capacity

Utah

27 reservoirs

Low

Average fill

29.2%

11,348 hm³ storedView →

Nevada

7 reservoirs

Low

Average fill

27.3%

10,128 hm³ storedView →

Montana

24 reservoirs

Average fill

81.0%

27,977 hm³ storedView →

South Dakota

14 reservoirs

Average fill

78.6%

25,367 hm³ storedView →

California

32 reservoirs

Average fill

60.9%

19,415 hm³ storedView →

North Dakota

11 reservoirs

Average fill

75.9%

18,211 hm³ storedView →

Oklahoma

47 reservoirs

Average fill

71.0%

12,939 hm³ storedView →

Texas

28 reservoirs

Average fill

65.4%

11,404 hm³ storedView →

Kentucky

16 reservoirs

Average fill

59.4%

9,153 hm³ storedView →

Missouri

8 reservoirs

Low

Average fill

32.8%

3,453 hm³ storedView →

Wyoming

25 reservoirs

Low

Average fill

38.2%

3,811 hm³ storedView →

Kansas

32 reservoirs

Average fill

60.1%

4,866 hm³ storedView →

Louisiana

3 reservoirs

Average fill

69.3%

4,976 hm³ storedView →

Idaho

20 reservoirs

Low

Average fill

25.5%

1,824 hm³ storedView →

Arizona

10 reservoirs

Average fill

61.1%

4,067 hm³ storedView →

New Mexico

16 reservoirs

Low

Average fill

21.7%

1,361 hm³ storedView →

Minnesota

9 reservoirs

Average fill

63.2%

3,377 hm³ storedView →

Tennessee

6 reservoirs

Average fill

86.9%

4,143 hm³ storedView →

Colorado

31 reservoirs

Average fill

45.8%

2,078 hm³ storedView →

Georgia

4 reservoirs

Average fill

89.7%

3,620 hm³ storedView →

Oregon

24 reservoirs

Critical

Average fill

16.4%

496 hm³ storedView →

Washington

15 reservoirs

Low

Average fill

29.8%

807 hm³ storedView →

Mississippi

5 reservoirs

Average fill

53.7%

1,399 hm³ storedView →

New York

8 reservoirs

Average fill

85.0%

1,860 hm³ storedView →

Virginia

4 reservoirs

Average fill

72.6%

1,508 hm³ storedView →

Ohio

27 reservoirs

Average fill

53.8%

990 hm³ storedView →

Massachusetts

2 reservoirs

Average fill

80.9%

1,461 hm³ storedView →

Nebraska

27 reservoirs

Average fill

47.3%

749 hm³ storedView →

Alabama

6 reservoirs

Average fill

95.7%

1,477 hm³ storedView →

Pennsylvania

13 reservoirs

Average fill

75.3%

1,158 hm³ storedView →

Indiana

4 reservoirs

Average fill

67.3%

596 hm³ storedView →

Iowa

4 reservoirs

Average fill

81.6%

693 hm³ storedView →

West Virginia

9 reservoirs

Average fill

77.9%

609 hm³ storedView →

North Carolina

3 reservoirs

Average fill

70.4%

404 hm³ storedView →

Illinois

3 reservoirs

Average fill

60.5%

257 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 →

All reservoirs

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US territory · tracked separately

Puerto Rico — 19 reservoirs

Puerto Rico publishes reservoir elevation, not storage, so its reservoirs cannot be given a fill % or ranked on the map above. They have their own page, in metres above sea level, with records back to 1990.

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States shown as N/A

Alaska, Connecticut, Delaware, District of Columbia, Hawaii, Maine, Maryland, Michigan, New Hampshire, New Jersey, 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

542

reservoirs

With data

542

reservoirs

Tracked capacity

357,547

hm³

Source: USGS NWIS · USACE CWMS · Bureau of Reclamation RISE · CDEC (California) · SRP (Arizona)

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 September 10, 2026, the reservoirs we track across United States that report live levels hold roughly 197,984 hm³ of water — about 56.8% of their combined capacity. Taken together, United States's reservoirs are within their normal operating range.

Across the region, 85 reservoirs are at critically low levels and 90 are low. Demopolis Lock and Dam is the fullest at 105.0%, while Mud Mountain Lake is the lowest at 0.0%.

Over the most recent week on record, 45 reservoirs rose and 98 reservoirs fell across United States.

Storage figures for United States come from USGS · USACE · BOR · CDEC · SRP; the most recent reading is from September 10, 2026. Each reservoir below links to its own page with full history and seasonal context.

United States at a glance

Reservoirs tracked: 542
Average fill: 56.8%
Water stored: 197,984 hm³
Combined capacity: 357,547 hm³
At critically low levels: 85
Fullest: Demopolis Lock and Dam (105.0%)
Lowest: Mud Mountain Lake (0.0%)
Last updated: September 10, 2026