|Location||Pend Oreille County, Washington|
|Owner(s)||City of Seattle|
|Dam and spillways|
|Type of dam||Arch-gravity|
|Impounds||Pend Oreille River|
|Height||340 ft (100 m)|
|Length||740 ft (230 m)|
|Total capacity||95,000 acre⋅ft (117,000,000 m3)|
|Catchment area||25,200 sq mi (65,000 km2)|
|Surface area||1,668 acres (6.75 km2)|
|Installed capacity||1,003.25 MW|
|Annual generation||3,587 GWh|
Boundary Dam is a concrete arch gravity-type hydroelectric dam on the Pend Oreille River, in the U.S. state of Washington. The dam is located in the northeast corner of Washington state, just south of the border with British Columbia, Canada. It is operated by Seattle City Light and makes up a significant portion of the City of Seattle's energy portfolio. On average, it provides upwards of 46% of the power generated by Seattle City Light. Boundary Powerhouse, located adjacent to the dam, is completely built inside of the rock that makes up the left abutment of the dam itself. It has a nameplate capacity of just over 1 gigawatt of generation. The component of the hydroelectric project were listed on the National Register of Historic Places in 2018.
A portion of the Kevin Costner film The Postman was filmed on the front of the dam. For a period of time in 1997, the dam's face had a facade of a town (Bridge City in the film).