Largest lakes & reservoirs in Washington by water volume
The estimated volume of water that a lake contains is measured at the lake’s normal elevation. By this measure, the world’s largest freshwater lake is Siberia’s Lake Baikal.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.
Note: In the United States, an acre foot is a unit of volume used to refer to large-scale bodies of water. It is defined by the volume of water needed to cover 1 acre of surface area to a depth of 1 foot.
You can find many of the the world’s largest lakes (by water volume) on LakeLubbers. Note: For some lakes, the water volume data is unknown or does not apply, so you may see fewer lakes than the total 58 articles we have published for Washington lakes.
Thinking about booking a Washington lake vacation home rental, cabin or hotel?
Use our free interactive vacation rental map to search and compare multiple vacation properties at a glance. Enter a lake name, a state or city and then simply click on a listing to compare all similar properties, best rates and availability for your dates.Search results: Sort lakes by water volume
Below are lakes within USA > US West Region > Washington > Compared by water volume. This list does not represent all lakes in Washington, only the 58 Washington lake articles we have published on the LakeLubbers website.
Lake name  |
Water vol. in ac-ft |
Lake description |
|---|---|---|
| Lake Roosevelt, WA (Northeast Washington, US West Region, USA, Washington) |
9,402,000 ac-ft | (Also known as Lake Franklin D. Roosevelt) Lake Roosevelt, located approximately 90 miles northwest of Spokane, Washington, covers 82,000 acres with a shoreline of 630 miles. Lake Roosevelt, al… |
| Lake Washington, WA (Seattle & Puget Sound Region, WA, US West Region, USA, Washington) |
2,350,000 ac-ft | Lake Washington has the distinction of being the second largest natural lake in the state of Washington. This glacial lake is long and narrow, a “ribb… |
| Riffe Lake (Seattle & Puget Sound Region, WA, US West Region, USA, Washington) |
1,686,000 ac-ft | (Also known as Riffe Reservoir, Mossyrock Lake, Davisson Lake) Riffe Lake by any other name would still be a fantastic recreational spot. The name confusion for this man-made reservoir in the Seattle and Puget Sou… |
| Lake Wallula, OR/WA (Eastern Oregon, Oregon, South Central Washington, US West Region, USA, Washington) |
1,350,000 ac-ft | Lake Wallula, a 64 mile long reservoir, is a wide open glassy lake that extends from northeastern Oregon to southeastern Washington. Lake Wallula rece… |
| Banks Lake, WA (North Central Washington, US West Region, USA, Washington) |
1,275,000 ac-ft | Banks Lake is a 27 mile equalizing reservoir and part of the Columbia Basin Project, a major water resource project to provide irrigation water to fer… |
| Lake Chelan, WA (North Central Washington, US West Region, USA, Washington) |
1,040,000 ac-ft | From the Salish Indian word for “deep notch”, Lake Chelan is the third deepest lake in the United States with a maximum depth of almost 1500 feet. Lak… |
| Lake Ozette, WA (Olympic Peninsula & Pacific Coast Region, WA, US West Region, USA, Washington) |
1,012,310 ac-ft | (Also known as Ozette Lake) Nestled in dense forest just a few miles from the Pacific Coast, Lake Ozette sits snuggled into Washington’s Olympic Peninsula tourism region, on the… |
| Ross Lake (British Columbia, Canada, Canada, North Central Washington, US West Region, USA, Washington) |
770,000 ac-ft | (Also known as Ross Reservoir) Spectacular Ross Lake is one of the seldom seen gems in north-central Washington. This fantastic 22-mile long reservoir covers 11,680 acres along the… |
| Whatcom Lake, WA (Northwest Washington & Islands, WA, US West Region, USA, Washington) |
767,700 ac-ft | (Also known as Lake Whatcom) Whatcom Lake is a 5,000-acre natural lake surrounded by mountainous terrain located in Whatcom County, Washington. Whatcom is from a Nooksack Indian w… |
| Potholes Reservoir, WA (North Central Washington, US West Region, USA, Washington) |
500,000 ac-ft | Potholes Reservoir was formed by the building of the O’Sullivan Dam which is one of the largest earthfill dams in the United States. The name “pothole… |
| Lake Cushman, WA (Olympic Peninsula & Pacific Coast Region, WA, US West Region, USA, Washington) |
450,000 ac-ft | Nestled in the foothills of the majestic Olympic Mountains, Lake Cushman is known for its clear, blue water and alpine beauty. With 23 miles of shorel… |
| Cle Elum Lake, WA (North Central Washington, US West Region, USA, Washington) |
436,900 ac-ft | (Also known as Lake Cle Elum) Providing much needed water to the dry, fertile soil of north-central Washington, Cle Elum Lake is the largest of four irrigation storage reservoirs i… |