Largest lakes & reservoirs in Washington by acres
There is no widely-accepted minimum surface area that defines a lake. What LakeLubbers describes as a lake, you might call a pond. Acreage of a lake (or sometimes square kilometers) is most often measured at the top surface area when the lake is at 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 in the comparison table below. Note: For some lakes, "Largest Lakes - Acres" data is unknown or does not apply, so you may see fewer lakes than the total 58 articles we have published for Washington lakes.
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Below are lakes within USA > US West Region > Washington > Compared by surface area in acres. This list does not represent all lakes in Washington, only the 58 Washington lake articles we have published on the LakeLubbers website.
Lake name  |
Surface area in acres |
Lake description |
|---|---|---|
| Lake Roosevelt, WA (Northeast Washington, US West Region, USA, Washington) |
82,000 ac | 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 Wallula, OR/WA (Eastern Oregon, Oregon, South Central Washington, US West Region, USA, Washington) |
38,800 ac | Lake Wallula, a 64 mile long reservoir, is a wide open glassy lake that extends from northeastern Oregon to southeastern Washington. Lake Wallula rece… |
| Lake Chelan, WA (North Central Washington, US West Region, USA, Washington) |
33,335 ac | 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… |
| Potholes Reservoir, WA (North Central Washington, US West Region, USA, Washington) |
27,800 ac | 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… |
| Banks Lake, WA (North Central Washington, US West Region, USA, Washington) |
27,000 ac | 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 Washington, WA (Seattle & Puget Sound Region, WA, US West Region, USA, Washington) |
21,500 ac | 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) |
11,830 ac | 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… |
| Ross Lake (British Columbia, Canada, Canada, North Central Washington, US West Region, USA, Washington) |
11,680 ac | 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… |
| Lake Celilo, OR/WA (Mt. Hood-The Gorge Region, OR, Oregon, Southwest Washington, US West Region, USA, Washington) |
9,400 ac | Also known as Dalles Lock and Dam Beautiful and serene Lake Celilo is located off of I-84 about an hour and a half east of Portland, Oregon. Lake Celilo stretches 24 miles long and str… |
| Lake Sacajawea, WA (South Central Washington, US West Region, USA, Washington) |
9,200 ac | Named after the Shoshone woman, Sacajawea, who was a member of the Lewis and Clark expedition, Lake Sacajawea is located in south-central Washington.… |
| Lake Entiat, WA (North Central Washington, US West Region, USA, Washington) |
9,100 ac | Also known as Rocky Reach Reservoir No trip to the north central part of Washington would be complete without a visit to Lake Entiat and the Rocky Reach Dam. Lake Entiat is a 9,100 acre… |
| Lake Ozette, WA (Olympic Peninsula & Pacific Coast Region, WA, US West Region, USA, Washington) |
7,550 ac | 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… |