Current level
870.98ft NGVD29
Reading from Oct 26, 2026
- Past 24 hours
- -0.01ft
- Past 7 days
- -0.10ft
- Past 30 days
- -0.67ft
- Trend
- Falling
Grand Lake St Marys was at 870.98 ft on October 26, falling 0.10 ft over the past week.
Last 30 days
Recent daily readings
| Date | Level (ft NGVD29) | Change |
|---|---|---|
| Oct 25, 2026 | 870.99 | -0.02 |
| Oct 24, 2026 | 871.01 | -0.01 |
| Oct 23, 2026 | 871.02 | -0.01 |
| Oct 22, 2026 | 871.03 | -0.02 |
| Oct 21, 2026 | 871.05 | -0.01 |
| Oct 20, 2026 | 871.06 | -0.02 |
| Oct 19, 2026 | 871.08 | -0.02 |
| Oct 18, 2026 | 871.10 | -0.01 |
| Oct 17, 2026 | 871.11 | +0.05 |
| Oct 16, 2026 | 871.06 | -0.12 |
| Oct 15, 2026 | 871.18 | -0.01 |
| Oct 14, 2026 | 871.19 | 0.00 |
| Oct 13, 2026 | 871.19 | -0.02 |
| Oct 12, 2026 | 871.21 | -0.02 |
Reading these numbers
Readings are elevations in feet above the National Geodetic Vertical Datum of 1929 (NGVD29), the reference most older dam and lake charts use. If you compare with a newer chart in NAVD88, expect a difference of a few feet. Our glossary explains NGVD29 vs NAVD88.
Reservoir levels are managed. Operators lower them ahead of flood season, hold them for summer recreation, and draw them down for dam work. When the lake falls well below its usual level, shallow points and stumps start showing up in places that are normally safe.
High water brings its own problems: floating debris after storms, flooded docks and courtesy piers, and no-wake rules near flooded campgrounds. A quick look at the trend before you hitch up saves a wasted trip.
The gauge is about 4 miles from the center of the lake and is listed by USGS as Grand Lake St Marys near Celina OH. Wind can pile water up at one end of a big lake for a few hours, so short spikes on a windy day are normal.
Grand Lake St Marys water level questions
What is the water level at Grand Lake St Marys today?
Grand Lake St Marys was at 870.98 ft on October 26, falling 0.10 ft over the past week.
Is Grand Lake St Marys rising or falling?
Over the last seven days the level has fallen (-0.10 ft), and it is -0.67 ft compared with 30 days ago.
Where does the Grand Lake St Marys water level data come from?
From the U.S. Geological Survey, gauge 403204084342601 (Grand Lake St Marys near Celina OH). USGS publishes provisional readings every 15 to 60 minutes; they can be revised later after quality checks.
How often is this page updated?
The page itself is rebuilt every day with the latest daily values, and the current reading refreshes straight from the USGS each time you open it.
Nearby lakes
If Grand Lake St Marys is blown out, these are the closest alternatives. Tap through for their water levels.