Grand Lake St. Marys

Mercer County, Ohio

Grand Lake St. Marys is a shallow 13,500-acre lake in Mercer and Auglaize counties, with an average depth of about 5-7 feet. It has unlimited horsepower, a 300-foot no-wake zone along the shore, and a no-boating wildlife refuge in the southwest corner.

Air temp in Montezuma, OH Loading current temperature…

Red pins match the numbered boat launches below. Map data © OpenStreetMap contributors.

Current air temperature at Grand Lake St. Marys (National Weather Service) ↗

Surface area13,500 acres

Max depth—

Shoreline52 mi

Boat motorsUnlimited horsepower

Species

Fishery rating out of 5.

Crappie●●●●●

Known as a top Ohio crappie lake; brush and docks hold fish in spring.

Channel Catfish●●●●○

Stocked and abundant in the shallow, fertile water.

Largemouth Bass●●●○○

Fair numbers around docks, riprap and brush.

Bluegill●●●○○

Common near docks and shoreline cover.

Yellow Perch●●●○○

Caught in open water and through the ice in winter.

Saugeye●●●○○

Stocked by ODNR; more often caught in fall and spring.

When they bite

Month-by-month activity for each target species.

	J	F	M	A	M	J	J	A	S	O	N	D
Crappie
Channel Catfish
Largemouth Bass
Bluegill

SlowFairGoodHot

Boat launches

10 launch sites. Fees and hours change, so confirm before you go.

1Windy PointPublic
State park ramp, south shoreDirections ↗
2West Bank RampPublic
State park ramp and fishing access, west endDirections ↗
3Mercelina ParkPublic
Public ramp, west endDirections ↗
4Marina RampPublic
State park marina ramp, east endDirections ↗
5Fries Channel RampPublic
State park ramp, east endDirections ↗
6Village of Montezuma RampPublic
Village ramp, south shoreDirections ↗
7Boat Club RampRamp
Launch with dock or marina, off State Route 703, St. Marys. No horsepower limit. (419) 394-3611.Directions ↗
8Campground RampRamp
Launch with dock or marina, off State Route 703, St. Marys. No horsepower limit. (419) 394-3611.Directions ↗
9Its It RampRamp
Public boat launch, Its It Road off State Route 127, St. Marys. No horsepower limit. (419) 394-3611.Directions ↗
More public accessPublic
See ODNR or the lake manager's website for all ramps and feesDirections ↗

Size & creel limits

Special rules for this lake, confirmed from official state regulations. Minimum size and daily limit.

Species	Min size	Daily limit
Crappie Black and white combined	9 in	30 / day

Other species in this lake: look up the limits at Ohio Department of Natural Resources, Division of Wildlife ↗

Verified October 2026. Rules change, so confirm current limits with the Ohio Department of Natural Resources, Division of Wildlife before you fish.

Bait & tackle nearby

Closest shops to the lake and its boat launches. Call ahead for live bait and hours.

Grand Lake Bait & TackleNearby
521 Jackson St, Saint Marys, OH 45885(419) 394-6306 Directions ↗
The OutdoorsmanNearby
172 E Bank Rd, St. Marys, OH 45885419-394-5769 Directions ↗
Windy Point Bait & TackleNearby
Celina, OH (near Windy Point)Directions ↗

Search more bait shops near Grand Lake St. Marys ↗

Local tips

Target brush piles and docks for crappie in spring.
The lake is shallow and turbid, so wind can change conditions fast; watch for stumps and shallows.
Stay out of the marked wildlife refuge in the southwest corner.

Angler reports

Water temp, what's biting, and anything else other anglers should know about Grand Lake St. Marys.

Loading reports...

View on interactive map

Zoom and pan on a street, satellite or terrain map. Red pins are boat launches; blue pins are bait shops nearby.