Reservoir · Illinois · United States · USACE CWMS
Sub Casey
17.9% full
Capacity
8.23 hm³
Volume stored
2 hm³
Coordinates
38.188°N, 88.927°W
Last updated
2026-05-27
Current fill
17.9%vs 7 days ago
-0.2%losing
vs 1 year ago
-5.6%year-over-year
7-day trend
→stable
Data source: USACE CWMS — US Army Corps of Engineers — daily reservoir storage volume. Design capacity is unavailable for this site, so fill % is estimated against the 5-year maximum storage and may overstate fullness. Last reading: 2026-05-27.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 38.188, -88.927 · Open in Google Maps
About Sub Casey
As of May 27, 2026, Sub Casey is filled to 17.9% of its total capacity, holding roughly 2 hm³ of water out of a maximum 8 hm³. At this level the reservoir is critically low.
Over the most recent week on record the fill level has held broadly steady (-0.2 pts), and it is 5.6 points below its level on the same date a year earlier.
Across the readings we hold for Sub Casey — 202 data points between June 13, 2021 and May 27, 2026 — the level has ranged from a low of 0.5% (February 24, 2026) to a high of 100.0% (July 17, 2021). On average the reservoir is fullest around July and at its lowest around April.
It is operated by USACE primarily for multiple purposes. It lies within the Illinois basin at 38.188°N, 88.927°W.
Key facts
- Current fill level
- 17.9%
- Water stored
- 2 hm³
- Total capacity
- 8 hm³
- 7-day change
- ▼ 0.2 pts
- Year-on-year
- ▼ 5.6 pts
- Primary use
- Multipurpose
- River basin
- Illinois
- Operator
- USACE
- Coordinates
- 38.188°N, 88.927°W
- Last updated
- May 27, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 27 May 2026 | 17.9% | 1 |
| 26 May 2026 | 18.1% | 1 |
| 25 May 2026 | 19.7% | 2 |
| 24 May 2026 | 22.8% | 2 |
| 23 May 2026 | 26.9% | 2 |
| 22 May 2026 | 31.9% | 3 |
| 21 May 2026 | 37.8% | 3 |
| 20 May 2026 | 42.3% | 3 |
| 19 May 2026 | 31.8% | 3 |
| 18 May 2026 | 24.9% | 2 |
| 17 May 2026 | 23.6% | 2 |
| 16 May 2026 | 17.2% | 1 |
Frequently asked questions
What is the current water level of Sub Casey?
As of May 27, 2026, Sub Casey is at 17.9% of its capacity, holding approximately 2 hm³ of water, according to USACE CWMS (US Army Corps of Engineers) data.
Is Sub Casey reservoir full?
No. As of May 27, 2026, Sub Casey is critically low at 17.9% of its capacity, so it is not full.
Is the water level at Sub Casey rising or falling?
The level at Sub Casey has been broadly stable over the latest week on record (-0.2 points).
How much water can Sub Casey hold?
Sub Casey has a total capacity of 8 hm³.
Where is Sub Casey reservoir located?
Sub Casey is located in Illinois, United States, within the Illinois basin (coordinates 38.188°N, 88.927°W).
What is Sub Casey used for?
Sub Casey is used primarily for multiple purposes, and is managed by USACE.