The 12 Biggest Lakes in Washington State

Written by Taiwo Victor
Updated: October 17, 2023
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With its temperate rainforests, mountain ranges, deep fjords, and Pacific shoreline, Washington is probably the most stunning state in the United States. The finest lakes in Washington have a unique aesthetic and natural charm, with glacier-carved coastlines and azure waters. You can have an exciting time exploring the areas and taking in the vistas because various hiking routes have access points. A variety of other recreational activities, such as fishing, boating, camping, and cross-country skiing, can be enjoyed in the state, making it a year-round destination. If you’re seeking the best Washington lakes for your next getaway, this article will list the 12 biggest lakes in the state.

The Biggest Lakes in Washington State

12. Little Kachess Lake

Kachess Lake

The 12th largest lake in Washington is Little Kachess Lake.

©Ricardo Martins from Gent, Belgium / Creative Commons – License

Located along the Kachess River’s course, Little Kachess Lake is a lake and reservoir in Washington state. The lake has 4,540 acres or 18.37 square kilometers of surface area. The Yakima Project, an irrigation project administered by the United States Bureau of Reclamation, uses the lake as a storage reservoir. It was originally a natural lake, although its size and drainage are regulated by Kachess Dam, a 115-foot (35-meter) high earth fill project erected in 1912. In contrast to Keechelus Lake, whose name translates to “few fish,” Kachess is named after a Native American phrase that means “more fish.”

11. Lake Whatcom

Lake Whatcom, Washington

Supplying water for about 85,000 people, Lake Whatcom is 5,003 acres in size.


Lake Whatcom supplies drinking water for approximately 85,000 people in Bellingham and Whatcom County. The lake, which is located in Whatcom County, Washington, is 5,003 acres (20.25 square kilometers) in size and runs for about 10 miles (16 kilometers) long and 1 mile (1.6 kilometers) wide. Swimming, fishing, motorboating, and other leisure activities are popular at the lake. Bellingham regulates water flow to keep the limit under control, store the input, meet the demands in drinking water, and maintain appropriate streamflow for the endangered Chinook salmon. The zebra mussel, New Zealand mud snail, and Asian carp are all invasive species that threaten Lake Whatcom.

10. Lake Crescent

Lake Crescent

Lake Crescent is the second-deepest lake in Washington.

© de droit

This crystal-clear, glacially sculpted lake is located 18 miles west of Port Angeles, near the Juan de Fuca Strait shoreline. The lake is one of Washington’s pride in beauty and surface area, encompassing 5,127 acres or 21 square kilometers. Lake Crescent is surrounded by several hiking routes and park facilities, providing ample opportunities for a day excursion or overnight stay. It is considered the second-deepest lake in Washington, with a maximum depth of 624 feet (190 meters), succeeding Lake Chelan. Hiking is a common sport in the area surrounding the lake.

9. Osoyoos Lake

Osoyoos Lake

Though Osoyoos Lake is the third-largest by size and third-deepest among Okanagan lakes, it is only the fourth-largest by volume.


Osoyoos Lake straddles the Canadian province of British Columbia and the U.S state of Washington. Osoyoos Lake is the third-largest by size and third-deepest among Okanagan lakes, yet it is only the fourth-largest by volume, covering 5,733 acres (23.2 square kilometers) of surface area.

‘Osoyoos’ is derived from the word ‘suius (soo-yoos),’ which means ‘place where two lakes meet.’ During the last Ice Age, a massive glacier carved out the Okanagan Valley. The glacial meltwaters created Osoyoos Lake and others in the basin when the ice sheet retreated. During severe drought, lake levels may drop below the average range, driving British Columbia to strive in keeping flows up to safeguard aquatic habitats and return migrating salmon.

8. Moses Lake

Moses Lake

The 8th largest lake in Washington is Moses Lake.


Moses Lake is a reservoir and lake located along Crab Creek in Washington State. Crab Creek is a tributary of the Columbia River, making Moses Lake a part of the Columbia River basin. It measures 6,800 acres (28 square kilometers) in surface area and boasts a maximum depth of 38 feet (12 meters) and a shoreline length of 62 miles. The lake where the city of the same name lies was once a shallow natural lake that was dammed for irrigation in the early 20th century. Moses Lake offers a variety of camping, boating, fishing, and swimming possibilities. It also provides a variety of species that anglers can feast on. The lake is home to rainbow trout up to 17 inches long, making it one of the best trout fishing sites. Anglers can also discover significant quantities of largemouth bass and walleye. Perch, crappies, and bluegills are also available, but their numbers are not as large.

7. Ozette Lake

Ozette Lake

Lake Ozette is Washington’s biggest unspoiled natural lake.


With 7,787 acres (29.5 square kilometers), Lake Ozette is Washington’s biggest unspoiled natural lake. Lake Ozette was given the Makah name “Kahouk,” which means “big lake.” Its maximum depth reaches 331 feet (101 meters) below sea level. The lake comprises three islands, namely, Tivoli, Garden Island, and Baby Island. Overnight tent campers prepared to make the long trip down the lake can enjoy Tivoli’s sandy coast, which is a kayaking and canoeing destination. 

6. Riffe Lake

Riffe lake

The sixth-largest lake in Washington is Riffe Lake.

© Ruth

Riffe Lake, created by the Mossyrock Dam, is another massive lake in Washington, measuring 11,830 acres (47.87 square kilometers). The lake boasts a healthy smallmouth bass population and has an open fishing season all year. Riffe Lake is a great place to catch landlocked coho, Chinook salmon, and the occasional huge brown trout. Cutthroat, landlocked salmon, rainbow trout, brown bullheads, and a few bluegill and crappie are among the warm freshwater fish present in the lake. Due to worries that the Mossyrock Dam could fall after a large earthquake and create catastrophic flooding, Tacoma Power decreased the lake’s maximum water level by 30 feet (9.1 meters) in 2017.

5. Lake Washington

Lake Washington

Lake Washington is the second-largest natural lake in the state of Washington.


In King County, Lake Washington runs between Seattle and Bellevue. It is King County’s largest lake and the state of Washington’s second-largest natural lake, behind Lake Chelan, with a surface area of 21,750 acres (88 square kilometers). Cutthroat trout, largemouth and smallmouth bass, yellow perch, and black crappie are among the popular game fish in this lake, which is open all year. Enjoying Lake Washington means visiting one of its lakefront parks. Many surrounding cities and towns around the lake have lakefront parks where visitors can have a picnic or walk along the beach walkway.

4. Banks Lake

Banks Lake

The fourth-largest lake in Washington is Banks Lake.


Banks Lake is a vast man-made reservoir in Eastern Washington that stretches from Coulee City to Electric City. This one-of-a-kind lake is part of the Columbia Basin Project, which supplies water and energy to the entire region. It boasts 26,890 acres (108.8 square kilometers) of surface area and is replete with smallmouth and largemouth bass, walleye, kokanee, yellow perch, rainbow trout, and whitefish. On the lake’s north coast lies Steamboat Rock State Park which is the hub of activities around the lake. Over 50,000 feet of freshwater beachfront can be found in the state park offering numerous activities. There are seven boat launches scattered throughout three sites that provide access to Banks Lake.

3. Potholes Reservoir

Potholes Reservoir

Measuring 27,800 acres, Potholes Reservoir is one of the largest lakes in Washington.

©Joe Mabel / Creative Commons – License

Potholes Reservoir is a man-made lake located in central Washington created by the O’Sullivan Dam. It is one of Washington’s largest lakes, measuring 27,800 acres or 112.5 square kilometers in surface area and bordered by 6,000 feet (1,800 meters) of coastline. Fed by Moses Lake, another massive reservoir in the state, Potholes Reservoir is filled with walleye, smallmouth bass, and largemouth bass, making it an ideal spot for anglers. Potholes State Park, a 640-acre (2.6 square kilometers) component of the Washington State Park System, is located on the reservoir’s coastline. Panfishing can be excellent in some years, although it varies yearly. Trout fishing for rainbows up to 20 inches can be excellent during the winter, early spring, and fall months.

2. Lake Chelan

The second-largest lake in Washington state is Lake Chelan.


Lake Chelan is a beautiful 33,340-acre (134.9 square kilometers) lake that stretches into the North Cascades’ eastern edge. It is the sixth deepest lake in North America, the third deepest in the United States, and the 25th deepest globally, with a maximum depth of 1,486 feet (453 meters). “Chelan” comes from a Salish word that means “deep water.” Chelan, the lake’s southernmost city, is a popular tourist destination and a great place to start if you want to get out on the water. Chinook salmon and lake trout can be caught in abundance in this lake. It’s a year-round pastime in the area with the option of hiring a fishing guide.

1. Franklin D. Roosevelt Lake

Franklin D. Roosevelt Lake

Franklin D. Roosevelt Lake is the biggest lake in Washington.

©Steven Pavlov / Creative Commons – License

The largest lake in the state is a reservoir with a surface area of 79,070 acres (320 square kilometers) and 603 miles of shoreline. Franklin D. Roosevelt Lake receives its water from the Columbia River and is surrounded by Lake Roosevelt National Recreation Area. The varied activities available here are suitable for visitors of all ages. Aside from the activities, it’s also a great place to enjoy a relaxed holiday with a few other people. Rainbow trout, white sturgeon, kokanee salmon, walleye, and smallmouth bass are among the lake’s many fish species. Except for white sturgeon, all species are available all year. Lake whitefish, burbot, and yellow perch are some of the other species you might luckily catch.

Summary of the 12 Biggest Lakes in Washington State

Here’s a recap of the 12 largest lakes in Washington, according to their total surface area measurements:

1Franklin D. Roosevelt Lake79,070 acres
2Lake Chelan33,340 acres
3Potholes Reservoir27,800 acres
4Banks Lake26,890 acres
5Lake Washington21,750 acres
6Riffe Lake11,830 acres
7Ozette Lake7,787 acres
8Moses Lake6,800 acres
9Osoyoos Lake5,733 acres
10Lake Crescent5,127 acres
11Lake Whatcom5,003 acres
12Little Kachess Lake4,540 acres

Bonus: Honorable Mentions That Did Not Make The List!

While we’ve already covered 12 of the largest lakes in the state, we decided that we should cover a few more honorable mentions we feel should also be explored.

Here are a few bonus lakes:

Diablo Lake is a man-made lake in the North Cascade mountains of northern Washington state, USA. It was formed by building Diablo Dam and is situated between Ross Lake and Gorge Lake along the Skagit River at an elevation of 1,201 feet above sea level.

Additionally, Rattlesnake Lake, located in the Rattlesnake Mountain Scenic Area in King County, Washington, covers 107.60 acres and sits at an elevation of 915 feet.

Furthermore, Lake Lenore, alternatively referred to as Lenore Lake, is a 1,670-acre body of water situated in Grant County, Washington, USA. This lake was shaped by the Missoula Floods in the lower Coulee, located just to the north of the town of Soap Lake, Washington. It can be found nestled between Alkali Lake to the north and Soap Lake to the south.

The photo featured at the top of this post is © FloNight (Sydney Poore) and Russell Poore / Creative Commons – License / Original

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About the Author

For six years, I have worked as a professional writer and editor for books, blogs, and websites, with a particular focus on animals, tech, and finance. When I'm not working, I enjoy playing video games with friends.

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