This Is the Deepest Lake in Each State

Published: October 7, 2024 by Ashley Haugen

According to the World Conservation Monitoring Centre (WCMC), a division of the United Nations Environment Program, out of the 195 nations worldwide, only 17 of them are megadiverse. To be labeled as megadiverse, countries must display outstanding biodiversity, with the main criteria being endemism at the species, genera, and family level, need to contain at least 5,000 species of endemic plants, and must have marine ecosystems within its borders. Megadiversity is vital for planet sustainability.

There are 17 countries labeled as megadiverse, which cover only about 10% of the Earth’s surface but are home to more than 70% of the planet’s species. These countries are Australia, Brazil, China, Colombia, the Democratic Republic of the Congo, Ecuador, India, Indonesia, Madagascar, Malaysia, Mexico, Papua New Guinea, Peru, the Philippines, South Africa, the United States, and Venezuela.

The United States comes in at number 10, with a high diversity of freshwater and marine ecosystems, and is estimated to have more than three million lakes in its borders (most of which are in Alaska). These lakes range in size and depth, saltwater and freshwater, and while almost every state has at least one natural lake in its borders (some have many more), according to the National Lake Assess (NLA) 2012, 48% of U.S. lakes are man-made.

U.S. Lakes

Snowy autumn day on Tally Lake in the Flathead National Forest, Montana, USA

The U.S. features tens of thousands of square miles of water area, which is key in its megadiverse designation. The nation’s water environments range from the ocean depths to raging rivers to inland lakes. The United States is estimated to have the third-most lakes of any country in the world, trailing only Canada and Russia.

While the exact number of lakes is hard to ascertain, discovering its depths can be done with verifiable numbers. Here is a look at the deepest lake in each U.S. state. (If you want to see which lakes are drying up, here is a list of famous lakes in danger of drying up, one of which is included in the list below.)

Determining the Deepest U.S. Lakes

To determine each state’s deepest lake, 24/7 Wall St. consulted various sources such as state government and geological survey websites. The Great Lakes were not included in this survey. These five lakes are massive natural wonders that touch eight U.S. states (Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania, and New York).

According to the Environmental Protection Agency, the maximum depths of the Great Lakes are:

Lake Superior – 1,332 feet (406 meters)
Lake Michigan – 925 feet (282 meters)
Lake Ontario – 802 feet (244 meters)
Lake Huron – 750 feet (229 meters)
Lake Erie – 210 feet (64 meters)

These lakes account for 21% of the world’s freshwater and are the deepest lakes in any state they touch. For example, Lake Superior is clearly the deepest lake in Minnesota. For our purposes, though, we excluded these lakes (which could be considered freshwater seas) and focused on the deepest inland lakes in each state.

Where Most Deep Lakes Are Found

The United States has lakes within the borders of all 50 states and while many of these are natural, a large portion are comprised of manmade reservoirs. Maryland is the only state that doesn’t have natural lakes but has more than 100 manmade impoundments, all of which were created through damming rivers, most of which are named reservoirs.

At the opposite end is the state of Alaska which has the most natural lakes in the country. The Last Frontier state has nearly 3,200 named lakes and over three million unnamed lakes. It is also a state with more lakes with depths of over 300 feet, which is interesting because the nation’s deepest lake is found in the northwestern part of the contiguous United States.

Depth Ranges

The deepest lake in each state showcases quite a range of depths, while the shallowest lake is just nine feet deep, less than the typical deep end of a swimming pool, which is ten feet deep. Compare that to the deepest lake in the U.S., which reaches 1,949 feet deep. The waters of this lake could completely cover One World Trade Center, the tallest building in the nation, with 173 feet to spare.

Here we have identified the deepest lake in each state.

Alabama – Lewis Smith Lake (also known as Smith Lake)

Type of Lake: Reservoir
Maximum Depth: 264 feet (80 meters)
Surface Area: 21,200 acres

Alaska – Lake Clark

Type of Lake: Freshwater lake
Maximum Depth: 1,054 feet (321 meters)
Surface Area: 81,920 acres

Arizona – Lake Mead

Type of Lake: Reservoir
Maximum Depth: 532 feet (162 meters)
Surface Area: 158,080 acres

Arkansas – Lake Ouachita

Type of Lake: Hydro-Electric reservoir
Maximum Depth: 200 feet (61 meters)
Surface Area: 66,324 acres

California – Lake Tahoe

Type of Lake: Ancient lake
Maximum Depth: 1,645 feet (501 meters)
Surface Area: 122,240 acres

Colorado – Grand Lake

Type of Lake: Glacial lake
Maximum Depth: 389 ft (119 meters)
Surface Area: 507 acres

Connecticut – Lake Lillinonah

View of Lake Lillinonah from Lovers Leap State Park in New Milford, Connecticut — Lovers Leap State Park is located along the northern edge of Lake Lillinonah.

Type of Lake: Reservoir
Maximum Depth: 110 feet (33.5 meters)
Surface Area: 1,547 acres

Delaware – Horsey Pond

Type of Lake: Freshwater reservoir
Maximum Depth: 9 feet (3 meters)
Surface Area: 46 acres

Florida – Deep Lake

Type of Lake: Natural sinkhole
Maximum Depth: 90 feet (27 meters)
Surface Area: 31 acres

Georgia – Carters Lake

Carters Lake Georgia — Carters Lake in Georgia is the deepest lake in the American South.

Type of Lake: Natural lake, reservoir
Maximum Depth: 450 feet (137 meters)
Surface Area: 3,200 acres

Hawaii – Halali’i Lake

Type of Lake: Ephemeral lake
Maximum Depth: Varies (Halali’i Lake’s depth depends on the weather. During the rainy seasons, it is Hawaii’s deepest lake)
Surface Area: 840 acres