# List of dams and reservoirs in Washington

As of 2023, the U.S. state of Washington has 1,242 dams that are able to impound 10 acre-feet or more of water and are regulated by the Washington State Department of Ecology (DOE). These include dams that produce hydroelectricity and create reservoirs for irrigation, drinking water, or recreational uses. According to the DOE, approximately 52 percent of dams in the state are privately-owned, while 31 percent are owned by local governments.
Approximately 87 percent of dams in Washington are earth fill dams, with the second most-common type being concrete gravity dams (6%). Only 113 dams in the state are taller than 50 feet (15 m). King County has 123 dams—the most of any county in the state. The majority of dams were built between 1960 and 1999. Proposals to remove underused dams and restore fish habitats emerged in the early 21st century with support from the state's Native American tribes; the first major dam removal was the Condit Dam near White Salmon in 2011, which was followed by two dams on the Elwha River near Port Angeles. As of 2024, 39 dams in Washington have been removed.
The largest dam in Washington, in terms of structural volume, reservoir capacity, and electricity production, is the Grand Coulee Dam on the Columbia River. It is the largest power station in the United States with a nameplate capacity of 6,809 megawatts and one of the largest concrete structures in the world. The tallest dam is Mossyrock Dam on the Cowlitz River in Lewis County, at 606 feet (185 m). The longest dam is O'Sullivan Dam on Crab Creek, at 19,000 feet (5,800 m); it is among the longest earth fill dams in the United States.

## List

Dams and reservoirs in Washington over 25 feet (7.6 m) :
| Dam | County | River | Reservoir | Type | Installed capacity (MW) | Height | Height | Reservoir capacity | Reservoir capacity | Year | Owner | Primary purpose(s) |
| Dam | County | River | Reservoir | Type | Installed capacity (MW) | ft | m | acre.ft | dam$^3$ | Year | Owner | Primary purpose(s) |
| Alder Dam | Pierce/ Thurston | Nisqually River | Alder Lake | Arch | 50.0 | 330 | 100 | 241,950 | 298,440 | 1945 | Tacoma Power | Hydroelectric |
| Bonneville Dam† | Skamania | Columbia River | Lake Bonneville | Gravity | 1,242.0 | 197 | 60 | 537,000 | 662,000 | 1937 | U.S. Army Corps of Engineers | Hydroelectric, Navigation |
| Boundary Dam | Pend Oreille | Pend Oreille River | Boundary Lake | Arch-gravity | 1,070.0 | 340 | 100 | 95,000 | 117,000 | 1967 | Seattle City Light | Hydroelectric |
| Box Canyon Dam | Pend Oreille | Pend Oreille River | Box Canyon Reservoir | Gravity | 90.0 | 62 | 19 | 60,000 | 74,000 | 1956 | Pend Oreille Public Utility District | Hydroelectric |
| Chief Joseph Dam | Douglas/ Okanogan | Columbia River | Rock Island Pool | Gravity | 2,620.0 | 135 | 41 | 516,000 | 636,000 | 1979 | U.S. Army Corps of Engineers | Hydroelectric |
| Cle Elum Dam | Kittitas | Cle Elum River | Cle Elum Lake | Earthfill | | 165 | 50 | 436,900 | 538,900 | 1933 | U.S. Bureau of Reclamation | Irrigation |
| Culmback Dam | Snohomish | Sultan River | Spada Lake | Rockfill | 112.0 | 262 | 80 | 165,774 | 204,479 | 1965 | City of Everett, Snohomish County PUD | Water supply |
| Cushman Dam No. 1 | Mason | North Fork Skokomish River | Lake Cushman | Arch | 43.2 | 235 | 72 | 453,400 | 559,300 | 1926 | Tacoma Power | Hydroelectric |
| Cushman Dam No. 2 | Mason | North Fork Skokomish River | Lake Kokanee | Arch | 81.0 | 175 | 53 | 8,000 | 9,900 | 1930 | Tacoma Power | Hydroelectric |
| Diablo Dam | Whatcom | Skagit River | Diablo Lake | Arch | 129.0 | 389 | 119 | 88,500 | 109,200 | 1930 | Seattle City Light | Hydroelectric |
| Dry Falls Dam | Grant | Grand Coulee | Banks Lake | Earthfill | | 123 | 37 | 1,275,000 | 1,573,000 | 1949 | U.S. Bureau of Reclamation | Irrigation |
| Gorge Dam | Whatcom | Skagit River | Gorge Lake | Gravity | 199.2 | 300 | 91 | 9,700 | 12,000 | 1961 | Seattle City Light | Hydroelectric |
| Grand Coulee Dam | Grant/ Okanogan | Columbia River | Franklin Delano Roosevelt Lake | Gravity | 6,809.0 | 550 | 170 | 9,562,000 | 11,795,000 | 1942 | U.S. Bureau of Reclamation | Irrigation, Hydroelectric, Flood control |
| Hiram M. Chittenden Locks and Dam | King | Lake Washington Ship Canal | Lake Washington | Gravity | 0 | 26 | 7.9 | 458,000 | 565,000 | 1916 | U.S. Army Corps of Engineers | Navigation |
| Howard A. Hanson Dam | King | Green River | Howard A. Hanson Reservoir | Earthfill | | 235 | 72 | 136,700 | 168,600 | 1961 | U.S. Army Corps of Engineers | Flood control, Water supply |
| John Day Dam† | Klickitat | Columbia River | Lake Umatilla | Gravity | 2,160.0 | 184 | 56 | 2,530,000 | 3,120,000 | 1971 | U.S. Army Corps of Engineers | Hydroelectric, Navigation |
| Ice Harbor Dam | Franklin/ Walla Walla | Snake River | Lake Sacajawea | Gravity | 603.0 | 100 | 30 | 249,000 | 307,000 | 1962 | U.S. Army Corps of Engineers | Hydroelectric, Navigation |
| Kachess Dam | Kittitas | Kachess River | Kachess Lake | Earthfill | | 112 | 34 | 239,000 | 295,000 | 1912 | U.S. Bureau of Reclamation | Irrigation |
| Keechelus Dam | Kittitas | Yakima River | Keechelus Lake | Earthfill | | 128 | 39 | 157,900 | 194,800 | 1917 | U.S. Bureau of Reclamation | Irrigation |
| LaGrande Dam | Pierce/ Thurston | Nisqually River | LaGrande Reservoir | Gravity | 65.0 | 192 | 59 | 2,700 | 3,300 | 1945 | Tacoma Power | Hydroelectric |
| Lake Chelan Dam | Chelan | Chelan River | Lake Chelan | Gravity | 59.2 | 40 | 12 | 677,400 | 835,600 | 1927 | Chelan County Public Utility District | Hydroelectric |
| Lake Tapps (Multiple dikes) | Pierce | Off-stream | Lake Tapps | Earthfill | | | | 48,258 | 59,525 | 1911 | Cascade Water Alliance | Recreation, Water supply (proposed) |
| Little Goose Dam | Columbia/ Whitman | Snake River | Lake Bryan | Gravity | 810.0 | 96 | 29 | 516,300 | 636,800 | 1970 | U.S. Army Corps of Engineers | Hydroelectric, Navigation |
| Long Lake Dam | Lincoln/ Stevens | Spokane River | Long Lake | Gravity | 71.0 | 213 | 65 | 105,000 | 130,000 | 1915 | Avista | Hydroelectric |
| Lower Baker Dam | Skagit | Baker River | Lake Shannon | Arch | 79.0 | 285 | 87 | 161,470 | 199,170 | 1925 | Puget Sound Energy | Hydroelectric |
| Lower Granite Dam | Garfield/ Whitman | Snake River | Lower Granite Lake | Gravity | 810.0 | 100 | 30 | 440,200 | 543,000 | 1975 | U.S. Army Corps of Engineers | Hydroelectric, Navigation |
| Lower Monumental Dam | Franklin/ Walla Walla | Snake River | Lake Herbert G. West | Gravity | 810.0 | 100 | 30 | 432,000 | 533,000 | 1969 | U.S. Army Corps of Engineers | Hydroelectric, Navigation |
| Masonry Dam | King | Cedar River | Chester Morse Lake/ Masonry Pool | Arch-gravity | 30.0 | 215 | 66 | 93,900 | 115,800 | 1915 | Seattle Public Utilities | Water supply, Hydroelectric |
| Mayfield Dam | Lewis | Cowlitz River | Lake Mayfield | Arch-gravity | 162.0 | 250 | 76 | 133,764 | 164,995 | 1963 | Tacoma Power | Hydroelectric |
| McNary Dam† | Benton | Columbia River | Lake Wallula | Gravity | 986.0 | 183 | 56 | 1,350,000 | 1,670,000 | 1954 | U.S. Army Corps of Engineers | Hydroelectric, Navigation |
| Merwin Dam | Clark/ Cowlitz | Lewis River | Lake Merwin | Arch-gravity | 136.0 | 313 | 95 | 422,000 | 521,000 | 1931 | PacifiCorp | Hydroelectric |
| Mossyrock Dam | Lewis | Cowlitz River | Riffe Lake | Arch | 300.0 | 606 | 185 | 1,685,000 | 2,078,000 | 1968 | Tacoma Power | Hydroelectric |
| Mud Mountain Dam | King | White River | Mud Mountain Lake | Earth/rockfill | 0 | 432 | 132 | 106,000 | 131,000 | 1948 | U.S. Army Corps of Engineers | Flood control |
| Pinto Dam | Grant | Off-stream | Billy Clapp Lake | Earthfill | | 130 | 40 | 21,200 | 26,100 | 1948 | U.S. Bureau of Reclamation | Irrigation |
| Priest Rapids Dam | Grant/ Yakima | Columbia River | Priest Rapids Lake | Gravity/ Embankment | 955.6 | 178 | 54 | 237,100 | 292,500 | 1961 | Grant County Public Utility District | Hydroelectric |
| Rock Island Dam | Chelan/ Douglas | Columbia River | Rock Island Pool | Gravity | 623.7 | 135 | 41 | 131,000 | 162,000 | 1933 | Chelan County Public Utility District | Hydroelectric |
| Rocky Reach Dam | Chelan/ Douglas | Columbia River | Lake Entiat | Gravity | 1,299.6 | 130 | 40 | 382,000 | 471,000 | 1969 | Chelan County Public Utility District | Hydroelectric |
| Ross Dam | Whatcom | Skagit River | Ross Lake | Arch | 460.0 | 540 | 160 | 1,435,000 | 1,770,000 | 1949 | Seattle City Light | Hydroelectric |
| Skookumchuck Dam | Thurston | Skookumchuck River | Skookumchuck Reservoir | Earthfill | 1.0 | 190 | 58 | 34,800 | 42,900 | 1970 | TransAlta | Water supply |
| South Fork Tolt River Dam | King | South Fork Tolt River | South Fork Tolt Reservoir | Earthfill | 6.55 | 200 | 61 | 57,900 | 71,400 | 1964 | Seattle Public Utilities | Water supply |
| Swift Dam | Skamania | Lewis River | Swift Reservoir | Earthfill | 240.0 | 512 | 156 | 755,600 | 932,000 | 1958 | PacifiCorp | Hydroelectric |
| The Dalles Dam† | Klickitat | Columbia River | Lake Celilo | Gravity | 1,878.3 | 200 | 61 | 330,000 | 410,000 | 1957 | U.S. Army Corps of Engineers | Hydroelectric, navigation |
| Tieton Dam | Yakima | Tieton River | Rimrock Lake | Earthfill | 15.6 | 319 | 97 | 203,600 | 251,100 | 1925 | U.S. Bureau of Reclamation | Irrigation |
| Toutle River Sediment Retention Structure | Cowlitz | North Fork Toutle River | | Earthfill | 0 | 184 | 56 | 160,000 | 200,000 | 1989 | U.S. Army Corps of Engineers | Sediment control |
| Upper Baker Dam | Whatcom | Baker River | Baker Lake | Arch | 91.0 | 312 | 95 | 285,000 | 352,000 | 1959 | Puget Sound Energy | Hydroelectric |
| Wanapum Dam | Grant/ Kittitas | Columbia River | Lake Wanapum | Gravity/ Embankment | 1,040.0 | 185 | 56 | 796,000 | 982,000 | 1963 | Grant County Public Utility District | Hydroelectric |
| Wells Dam | Chelan/ Douglas | Columbia River | Lake Pateros | Gravity | 851.4 | 160 | 49 | 331,200 | 408,500 | 1967 | Douglas County Public Utility District | Hydroelectric |
| Wynoochee Dam | Grays Harbor | Wynoochee River | Wynoochee Lake | Gravity | 10.8 | 175 | 53 | 69,405 | 85,610 | 1972 | City of Aberdeen | Water supply |
| Yale Dam | Clark/ Cowlitz | Lewis River | Yale Lake | Earthfill | 134.0 | 323 | 98 | 402,000 | 496,000 | 1953 | PacifiCorp | Hydroelectric |

## Removed dams

* Condit Dam, on the White Salmon River in Klickitat County
* Elwha Dam and Glines Canyon Dam, on the Elwha River in Clallam County