Boundary Dam
| Boundary Dam | |
|---|---|
.jpg) | |
  Boundary Dam Location of the dam in Washington | |
| Country | United States |
| Location | Pend Oreille County, Washington |
| Coordinates | 48°59′14″N 117°20′51″W / 48.98722°N 117.34750°W |
| Purpose | Power |
| Status | Operational |
| Opening date | 1967 |
| Owner | City of Seattle |
| Dam and spillways | |
| Type of dam | Arch-gravity |
| Impounds | Pend Oreille River |
| Height | 338 ft (103 m) |
| Length | 740 ft (225.6 m) |
| Width (crest) | 8.0 ft (2.44 m) |
| Width (base) | 32.0 ft (9.75 m) |
| Spillways | 2 |
| Reservoir | |
| Total capacity | 95,000 acre⋅ft (117 GL) |
| Catchment area | 25,200 sq mi (65,000 km2) |
| Surface area | 1,668 acres (675 ha) |
| Boundary Dam Hydro Power Plant | |
| Coordinates | 48°59′14″N 117°20′51″W / 48.98722°N 117.3475°W |
| Operator | Seattle City Light |
| Commission date |
|
| Type | Conventional |
| Turbines |
|
| Installed capacity | 1,159.7 MW (1.5552×106 hp) |
| Annual generation | 3,020 GWh (10,900 TJ) (2024) |
| [1][2][3][4] | |
The Boundary Dam is a concrete arch-gravity dam across the Pend Oreille River, located in the U.S. state of Washington, in the northeast corner of the state. Completed in 1967 for the conventional generation of hydroelectricity, the dam is operated by Seattle City Light[5] and generates a significant portion of the City of Seattle's energy portfolio. On average, it provides between 46 and 60 percent of the power generated by Seattle City Light.[6]
The dam wall is 338 feet (103 m) high and 738 feet (225 m) long.[4]
The underground powerhouse, called the Boundary Dam Hydro Power Plant, is completely built inside of the rock that makes up the left abutment of the dam wall. It has a nameplate capacity of just over 1 gigawatt (1,300,000 hp) of generation. The hydroelectric project was listed on the National Register of Historic Places in 2018.
The 1997 film The Postman was partially filmed at the dam. A facade of the town (Bridge City in the film) appeared on the face of the dam for a period of time that year.[7]
Hydroelectric power capacity
| Generator (all Francis-type) |
Nameplate capacity[2] |
Brand[4] | Commissioned[8] | |
|---|---|---|---|---|
| MW | hp | |||
| 51 | 180.5 | 242,100 | General Electric | October 1967 |
| 52 | 161.5 | 216,600 | General Electric | August 1967 |
| 53 | 158.4 | 212,400 | General Electric | September 1967 |
| 54 | 180.5 | 242,100 | General Electric | August 1967 |
| 55 | 239.4 | 321,000 | Toshiba | November 1985 |
| 56 | 239.4 | 321,000 | Toshiba | May 1986 |
| Total[a] | 1,159.7 | 1,555,200 | ||
Climate
| Climate data for Boundary Dam, Washington, 1991–2020 normals: 1837ft (560m) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Mean daily maximum °F (°C) | 32.6 (0.3) |
38.3 (3.5) |
47.5 (8.6) |
58.0 (14.4) |
67.2 (19.6) |
72.4 (22.4) |
83.6 (28.7) |
84.6 (29.2) |
72.9 (22.7) |
55.7 (13.2) |
40.3 (4.6) |
32.2 (0.1) |
57.1 (13.9) |
| Daily mean °F (°C) | 26.7 (−2.9) |
29.9 (−1.2) |
37.1 (2.8) |
45.3 (7.4) |
54.0 (12.2) |
60.1 (15.6) |
67.8 (19.9) |
67.2 (19.6) |
57.8 (14.3) |
45.2 (7.3) |
34.2 (1.2) |
26.8 (−2.9) |
46.0 (7.8) |
| Mean daily minimum °F (°C) | 20.9 (−6.2) |
21.5 (−5.8) |
26.8 (−2.9) |
32.6 (0.3) |
40.9 (4.9) |
47.8 (8.8) |
52.0 (11.1) |
49.8 (9.9) |
42.6 (5.9) |
34.6 (1.4) |
28.1 (−2.2) |
21.4 (−5.9) |
34.9 (1.6) |
| Average precipitation inches (mm) | 3.10 (79) |
1.98 (50) |
2.35 (60) |
2.21 (56) |
2.60 (66) |
3.18 (81) |
1.42 (36) |
0.81 (21) |
1.32 (34) |
2.40 (61) |
3.23 (82) |
3.60 (91) |
28.2 (717) |
| Average snowfall inches (cm) | 18.50 (47.0) |
7.70 (19.6) |
3.40 (8.6) |
0.10 (0.25) |
0.00 (0.00) |
0.00 (0.00) |
0.00 (0.00) |
0.00 (0.00) |
0.00 (0.00) |
0.10 (0.25) |
6.80 (17.3) |
18.20 (46.2) |
54.8 (139.2) |
| Source: NOAA[9] | |||||||||||||
See also
Notes
References
- ^ "Boundary Dam". NPDP Dam Directory. Stanford University. Archived from the original on July 16, 2011.
- ^ a b "Generator 2026". EIA 860M. January 2026.
- ^ "Generator 2024". EIA-923. 2024.
- ^ a b c d "Projects: Boundary Hydroelectric Power Plant, Washington". NS Energy. July 16, 2018. Retrieved April 11, 2026.
- ^ "Seattle City Light: Boundary Project". Archived from the original on November 25, 2011. Retrieved September 26, 2011.
- ^ "Projects: Boundary Dam". Schnabel Engineering. 2026 [2015]. Retrieved April 11, 2026.
- ^ "Boundary Dam". Seattle Municipal Archives.
- ^ a b "Boundary Dam Hydro Power Plant WA USA". Global Energy Observatory. September 18, 2015. Retrieved April 11, 2026.
- ^ "Boundary Dam, Washington 1991-2020 Monthly Normals". Retrieved August 14, 2023.