Grand Lake St. Marys, Ohio, USA

Lake Locations:

USA - Midwest - Ohio - Northwest -

Also known as:  Grand Lake

With its sail billowing in the wind, the sailboat glides in front of the lighthouse. It’s a rare scene for an inland lake, but Grand Lake St. Marys is a rare lake. Three lighthouses grace the lake’s shores. The north shore’s Northwood Lighthouse was constructed in 1923 and is on the National Register of Historic Places. It is only visible by boat. Grand Lake’s lighthouses, however, aren’t the only reason to take to the water. The lake in northwest Ohio stretches nine miles long with plenty of water for boating, and the fishing is exceptional year round.

Grand Lake St. Marys was created as a storage reservoir for the Miami and Erie Canal. Known as a canal feeder lake, it is one of several reservoirs that were used to keep water levels stable and maintain the canal’s five foot depth. Construction of Grand Lake was started in 1837 and completed in 1845. At the time of its completion, it was the largest manmade reservoir in the world. Today, it is still the largest inland lake in the state of Ohio.

With an average depth of just six feet and the majority of the lake under seven feet deep, Grand Lake St. Marys is a shallow lake. Its 12,900 acres sprawl across parts of Auglaize and Mercer Counties. Grand Lake is an impoundment of Coldwater Creek, and its outflow is Beaver Creek. Part of the lake’s 74 mile shoreline is in the Grand Lake St. Marys State Park. Established in 1949, it is one of Ohio’s oldest state parks.

The Grand Lake St. Marys State Park includes a campground with RV sites and cabins. There is a beach for swimming and several public boat launches. A state wildlife refuge on the southwest corner of Grand Lake provides a stopping place for migratory birds and waterfowl including Canada geese, grebes, swans, egret, loons and cormorants. Several pairs of nesting bald eagles make their home in the refuge. The Ohio Department of Natural Resources (DNR) holds a lottery for the many duck blinds along the lakeshore during hunting season. Only a mile and a half from the state park, the 47 mile long Miami-Erie Trail, part of the Buckeye Trail, provides an opportunity to hike across the state.

In the past, walleye were stocked in Grand Lake St. Marys, and there are abundant populations of largemouth bass and black and white crappie. In the winter, the yellow perch fishing is exceptional. Anglers can compete in several fishing tournaments held on Grand Lake throughout the year. The St. Mary’s Fish Hatchery is on the eastern shore of the lake. It produces saugeye, walleye, channel catfish and bass that are stocked in lakes across the state.

In addition to the public facilities maintained by the state park, there are several private marinas with boat launches, fuel and boat rentals. After a day on the water, fishing, boating or water skiing, guests can relax at one of Grand Lake’s waterfront restaurants before retiring to one of the vacation rentals, cottages or bed and breakfasts. The town of St. Marys has any additional amenities a visitor might need including real estate for sale for those wishing to extend their stay. A short drive from Grand Lake St. Marys, Wapakoneta’s Armstrong Air and Space Museum is dedicated to Ohio’s native son and the first man to set foot on the moon: Neil Armstrong. The museum includes the Gemini VIII aircraft and artifacts from the Apollo 11 mission and is sure to awaken the inner space explorer in anyone.

The rich history, spacious water, and abundant fish combine to make Grand Lake St. Marys a rare treat and a fantastic Ohio destination.

Lake Updates:

May 19, 2011: Warning signs are once again being posted. Toxic blue-green algae have returned to the lake. Alum treatment has been delayed to June due to heavy spring rains.

April 2011: Optimism is high for this summer’s recreation. State agencies will treat the lake with alum and hydrogen peroxide to lock up phosphorous feeding the algae, dredging phosphorus-rich sediment, and creating wetlands to intercept farm runoff.

February 7, 2011: Ohio’s Environmental Protection Agency lifted the advisory against eating fish caught from Grand Lake St. Marys. The EPA tested channel catfish, largemouth bass, crappie, and bluegill collected from the lake last fall.

October 29, 2010: Grand Lake St. Marys is no longer under a toxin advisory. Although state offficials declared the lake safe for recreation, advisories against fish consumption remain.

Health Alert, Summer 2010: Officials posted warning signs around the lake due to blue-green algae, known as cyanobacteria, that have made the lake unsafe for swimming, boating, and fishing. Algae feed on fertilizer and manure runoff from nearby farms that flow into streams that empty into the lake. Ohio’s governor announced a series of steps, starting in September, to combat the algae outbreak.

Things to do at Grand Lake St. Marys

  • Vacation Rentals
  • Fishing
  • Fishing Tournaments
  • Boating
  • Sailing
  • Swimming
  • Beach
  • Water Skiing
  • Camping
  • Campground
  • Cabin Rentals
  • Hiking
  • Hunting
  • Wildlife Viewing
  • Birding
  • State Park
  • Museum

Fish species found at Grand Lake St. Marys

  • Bass
  • Black Bass
  • Bluegill
  • Catfish
  • Channel Catfish
  • Crappie
  • Largemouth Bass
  • Perch
  • Saugeye Perch
  • Sunfish
  • Walleye
  • White Crappie
  • Yellow Perch

Grand Lake St. Marys Photo Gallery

Grand Lake St. Marys Statistics & Helpful Links

divider

Lake Type: Artificial Reservoir, Dammed

Water Level Control: Ohio Dept. of Natural Resources

Surface Area: 12,900 acres

Shoreline Length: 74 miles

Normal Elevation (Full Pond): 871 feet

Average Depth: 6 feet

Maximum Depth: 16 feet

Completion Year: 1845

Trophic State: Hypereutrophic

Spread the word! Share our Grand Lake St. Marys article with your fellow Lake Lubbers!

Trophic State | LakeLubbers

Trophic State measures the level of algae and nutrients in a lake.

An oligotrophic lake is very clear (blue in color) and does not support much plant or fish life. A hyper-oligotrophic lake is the clearest of all lakes, and is nearly devoid of plants and fish.

A mesotrophic lake is slightly green and supports a moderate degree of plant and fish life. A lake's most desired trophic state is generally this mid-point - the mesotrophic state.

A eutrophic lake is somewhat murky and supports a large amount of plant and fish life. A hypereutrophic lake is clouded with algae, plant life, and fish life. A eutrophic or hyper-eutrophic lake can be difficult to navigate by boat - and is often an unpleasant place to swim.

The use of phosphorus-rich and nitrogen-rich fertilizer on lawns and golf courses surrounding a lake can cause it to become eutrophic or hypereutrophic.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Catchment or Drainage Area | LakeLubbers

This is the surrounding area that drains into a lake, including land, rivers and their tributaries. This is also known as the lake's "catchment basin".

Small lakes at the highest peaks of mountains have small drainage areas. The world's oceans have the largest drainage areas.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Lake-Area Population | LakeLubbers

This is the estimated number of people who live in a house with a view of a lake, plus those who self-describe the lake as their home, for example: "I live at Smith Mountain Lake."


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Water Residence Time | LakeLubbers

This is the estimated time that it takes for an amount of water equal to the entire volume of a lake to flow out of - or evaporate from - the lake.

Residence Time can be as short as a few days for fast-flowing small lakes, and can exceed 100 years for slow-flowing large lakes.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Completion Year | LakeLubbers

This is the year that a reservoir was first filled to the reservoir's normal elevation - or the year that a natural lake was first dammed. A large reservoir can take more than a year to fill after its dam is first closed.

The Grand Anicut in southern India is generally considered the world's oldest dam that still operates. Grand Anicut was constructed in the second century BC. It now impounds an irrigation network that includes roughly one million acres.

You can find many of the the world's newest reservoirs on LakeLubbers. Many of the world's oldest reservoirs appear on the last page of that list.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Water Volume | LakeLubbers

This is the estimated volume of water that a lake contains -- measured at the lake's normal elevation. By this measure, the world's largest freshwater lake is Siberia's Lake Baikal.

You can find many of the the world's largest lakes (by water volume) on LakeLubbers.

Water Volume can be measured in acre-feet, in cubic miles, or in cubic kilometers. One acre-foot is the amount of water needed to cover one acre (43,560 square feet) to a depth of one foot. One cubic mile equals 3,379,200 acre-feet. One cubic kilometer equals 810,713 acre-feet.

1 acre-foot is equal to 325,851 US gallons. Siberia's Lake Baikal contains about 6,276,367,740,000,000 gallons of freshwater - nearly 1 million gallons for every living person on earth.

The other - and more widely used - measure of a lake's size is the lake's surface acreage. By that measure, the world's largest freshwater lake is North America's Lake Superior.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Maximum Depth | LakeLubbers

This is the estimated greatest depth of the water in a lake -- measured at the lake's normal elevation. The world's deepest lake is Siberia's Lake Baikal; that lake's maximum depth is estimated at 5,314 feet.

You can find many of the the world's deepest lakes on LakeLubbers. If you select the last page of that list, you will find the (maximum depth of) the shallowest lakes in our database.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Average Depth | LakeLubbers

This is the estimated average depth of the water in a lake -- measured at the lake's normal elevation. If the water volume and surface area of a lake are known, an estimate of the lake's average depth can be calculated:

Water volume ÷ Surface Area = Average Depth

Example: 1,000,000 acre-feet ÷ 20,000 acres = 50 feet average depth


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Maximum Elevation | LakeLubbers

This is a lake's highest water level, measured by the lake's surface distance above sea level, that can occur during flooding. A lake's highest possible maximum elevation is usually the top of the lake's dam or spillway.

At lakes that include residential development, government regulations usually forbid the construction of homes below a lake's maximum elevation.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Minimum Elevation | LakeLubbers

This is a lake's lowest water level, measured by the lake's surface distance above sea level, that can be reasonably expected to occur. Low lake levels can occur due to deliberate seasonal draw downs for irrigation or impending snow melt, reduced water inflows, drought and evaporation, residential or commercial water demands, and hydropower generation.

Some lakes' minimum and maximum elevations are virtually the same. Lakes that generate hydropower may vary by several feet - according to power demand. Lakes whose primary purpose is to prevent flooding can seasonally vary by 100 feet or more.

When some lakes reach their minimum elevation, their boat ramps may not be long enough to permit boat access - and boats docked on shallow parts of the lake may end up on dry ground. In those cases, kayakers and shore-based anglers may be among the few happy recreational users of the lake.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Normal Elevation | LakeLubbers

This is a lake's normal water level, measured by the lake's surface distance above sea level. For a reservoir, this water level is also known as "full pond" or "full pool".

You can find many of the world's highest-elevated lakes on LakeLubbers. Lakes with the lowest elevations (known by LakeLubbers) are shown on the final page of that list.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Shoreline Length | LakeLubbers

This is the length of the exterior shoreline around a lake - measured at the lake's normal elevation. The shoreline length can be considerably shorter or longer when lake water levels are lower or higher than normal.

A lake with many coves has a much longer shoreline than a lake of similar surface area that is nearly circular in shape.

When known, the shoreline miles that we report in our statistics include only the lake's exterior shoreline, and exclude the shorelines of islands located within a lake's boundaries. In lakes with many islands, those islands' combined shorelines may exceed a lake's exterior shoreline.

You can find many of the world's longest-shoreline lakes on Lakelubbers.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Surface Area | LakeLubbers

This is the area (acreage, square kilometers, etc.) of the top surface area of a lake - measured at a lake's normal elevation. The surface area can be considerably smaller or larger when lake levels are lower or higher than normal. North America's Lake Superior is the world's largest freshwater lake by this measure.

The other measure of a lake's size is the lake's water volume. By that measure, the world's largest freshwater lake is Lake Baikal in Siberia.

You can find many of the world's largest lakes (acres) on Lakelubbers. There is no widely-accepted minimum surface area that defines a lake. What Lakelubbers describes as a lake, you might call a pond. The smallest lake that Lakelubbers currently includes is Hawaii's 2-acre Lake Waiau.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Water Level Control | LakeLubbers

This is the organization that controls water releases or outflows from the lake or reservoir. In the USA, this is often the US Army Corps of Engineers, a power company, a municipal water system, an irrigation district, or a paper manufacturing company. In the case of private or gated lakes, a homeowners' association may be the lake's controlling authority.

Many lakes cross borders, including North America's Great Lakes. The control of such lakes and their coveted freshwater may be amicably shared - or hotly disputed.

"Water wars" continue at many lakes as growing populations and crop irrigation needs compete for the freshwater that lakes contain.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.

Lake Type | LakeLubbers

There are 3 basic types of lakes that are currently included on LakeLubbers. 2 types may be dammed or not dammed, producing 5 classifications.

- A Reservoir is a man-made freshwater lake that is usually created by damming rivers.

- A Natural Freshwater Lake occurs naturally - often by glacial activity - and has a salinity of less than 30 parts per thousand. It may be dammed to produce electricity or for other reasons.

- A Natural Saltwater Lake occurs naturally and has a salinity of more than 30 parts per thousand (ppt). It may be dammed.

"Brackish" water may be categorized as freshwater or saltwater, depending on its salt content (salinity). Oligohaline water has less than 15 ppt of salt. Mesohaline water has 15-29 ppt. Polyhaline has 30-335 ppt.


Lakes for Vacation and Recreation

Except as noted, Copyright © LakeLubbers LLC. All Rights Reserved.