871.48 ft NGVD29
level At full pool — this gauge's public record is too short for seasonal comparisons
Reading comes straight from U.S. Geological Survey National Water Information System (USGS gauge 403204084342601) and updates live when you load this page.
Is Grand Lake St. Marys full?
Yes — at full pool as of October 1, 2026
How full is Grand Lake St. Marys? Not as a percentage: no storage figure comes through with this gauge reading, and a share of capacity worked out from the elevation alone would be a guess — how much water a reservoir holds at a given level is a curve only the operator's own capacity table knows. Feet from full pool is what the operator publishes, and it is the figure above.
Full pool, datum, and the gauge
"Full pool" here means the conservation pool — the level the lake is designed to hold for water supply and recreation, not the flood-control space above it. The full explainer covers flood pool and dead pool too.
| Full pool | 871.50 ft NGVD29 · per Ohio DNR full-pool reference |
|---|---|
| Gauge | USGS gauge 403204084342601 · U.S. Geological Survey National Water Information System |
| Datum | NGVD29 — Full pool here is the 871.5 ft crest of the 1997 west spillway, with a 50-ft notch at 870.6 ft — an effective band rather than a single engineered figure. |
| Last verified | August 15, 2026 |
LakeDates reports lake level, not ramp status. Whether a given ramp or marina is usable at this level varies ramp by ramp — call the marina before you tow.
Quick answers
What is the lake level for Grand Lake St. Marys today?
Grand Lake St. Marys is at 871.48 ft (NGVD29) as of October 1, 2026 — At full pool — this gauge's public record is too short for seasonal comparisons.
Is Grand Lake St. Marys full?
Yes — at 871.48 ft on October 1, 2026, Grand Lake St. Marys is at full pool (871.50 ft NGVD29).
How full is Grand Lake St. Marys?
Not as a percentage: no storage figure comes through with this gauge reading, and a share of capacity worked out from the elevation alone would be a guess — how much water a reservoir holds at a given level is a curve only the operator's own capacity table knows. Feet from full pool is what the operator publishes, and it is the figure above.
What is full pool for Grand Lake St. Marys?
Full pool (the conservation pool) for Grand Lake St. Marys is 871.50 ft NGVD29, per Ohio DNR full-pool reference. Levels above it use flood storage; levels below it are drawdown.