871.34 ft NGVD29
level 0.2 ft below 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.
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 — 62614 NGVD29. 871.5 = crest of the 1997 ODNR west spillway (50-ft center notch at 870.6) - the lake's effective full pool band; source is the spillway historical-marker text, not an ODNR engineering page, so treat as reference. |
| 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
How full is Grand Lake St. Marys right now?
Grand Lake St. Marys is at 871.34 ft (NGVD29) as of August 15, 2026 — 0.2 ft below full pool — this gauge's public record is too short for seasonal comparisons
Is Grand Lake St. Marys full?
Not quite — at 871.34 ft, Grand Lake St. Marys is 0.2 ft below its full pool of 871.50 ft (NGVD29).
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.