State · United States · USGS · BOR · USACE · CDEC
Illinois
81.7% average fill
Measured
5
Volume stored
783 hm³
Measured capacity
958 hm³
Critical
1
Low level
1
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Reservoirs
Sorted by capacityShelbyville Pool
Updated 2026-09-17
Carlyle Pool
Updated 2026-09-17
Rend Pool
Updated 2026-09-17
Sub
lowUpdated 2026-09-17
Sub Casey
criticalUpdated 2026-09-15
Storage from official US gauges (USGS, USACE, Bureau of Reclamation, CDEC). Fill % uses design capacity from the National Inventory of Dams where available; a few sites without a match fall back to the 5-year maximum.
About reservoirs in Illinois
As of September 17, 2026, the reservoirs we track across Illinois that report live levels hold roughly 783 hm³ of water — about 81.7% of their combined capacity. Taken together, Illinois's reservoirs are high.
Across the region, 1 reservoir is at critically low levels and 1 is low. Carlyle Pool is the fullest at 105.0%, while Sub Casey is the lowest at 6.0%.
Over the most recent week on record, 1 reservoir rose and 1 reservoir fell across Illinois.
Storage figures for Illinois come from USGS · USACE · BOR · CDEC; the most recent reading is from September 17, 2026. Each reservoir below links to its own page with full history and seasonal context.
Illinois at a glance
- Reservoirs tracked
- 5
- Average fill
- 81.7%
- Water stored
- 783 hm³
- Combined capacity
- 958 hm³
- At critically low levels
- 1
- Fullest
- Carlyle Pool (105.0%)
- Lowest
- Sub Casey (6.0%)
- Last updated
- September 17, 2026