| Valeira Dam | |
| Name Official: | Barragem da Valeira |
| Location Map: | Portugal |
| Coordinates: | 41.1605°N -7.3742°W |
| Country: | Portugal |
| Location: | municipality São João da Pesqueira, Viseu District |
| Purpose: | Power |
| Status: | O |
| Construction Began: | 1971 |
| Opening: | 1975 |
| Owner: | Companhia Portuguesa de Produção de Electricidade |
| Operator: | Energias de Portugal |
| Dam Type: | Concrete gravity dam |
| Dam Crosses: | Douro |
| Dam Height Foundation: | 48m (157feet) |
| Dam Length: | 380m (1,250feet) |
| Dam Elevation Crest: | 113m (371feet) |
| Dam Width Crest: | 6m (20feet) |
| Dam Volume: | 220000m2 |
| Spillway Type: | Dam body |
| Spillway Capacity: | 18000m3/s |
| Res Capacity Total: | 97000000m2 |
| Res Capacity Active: | 8000000m2 |
| Res Surface: | 7.95km2 |
| Res Elevation: | 105m (344feet) |
| Plant Operator: | Energias de Portugal |
| Plant Commission: | 1976 |
| Plant Hydraulic Head: | 31.5m (103.3feet) (max) |
| Plant Turbines: | 3 x 82.4 MW Kaplan-type |
| Plant Capacity: | 240 MW |
| Plant Annual Gen: | 610.7 GWh |
Valeira Dam (Portuguese: Barragem da Valeira|links=no) is a concrete gravity dam on the Douro, where the river forms the border line between the districts of Viseu and Bragança. It is located in the municipality São João da Pesqueira, in Viseu District, Portugal.
Construction of the dam began in 1971. The dam was completed in 1975. It is owned by Companhia Portuguesa de Produção de Electricidade (CPPE).
Valeira Dam is a 48 m tall (height above foundation) and 380 m long gravity dam with a crest altitude of 113 m. The volume of the dam is 220,000 m3. The spillway with 5 radial gates is part of the dam body (maximum discharge 18,000 m3/s).
At full reservoir level of 105 m the reservoir of the dam has a surface area of 7.95 km2 and a total capacity of 97 mio. m³. The active capacity is 8 (12, 13 or 13,04) mio. m³.
The run-of-the-river hydroelectric power plant was commissioned in 1976 (1975). It is operated by EDP. The plant has a nameplate capacity of 240 (216) MW. Its average annual generation is 610.7 (663, 748 or 801) GWh.
The power station contains 3 Kaplan turbine-generators with 82.4 (72) MW (80 MVA) each in a dam powerhouse located on the right side of the dam. The turbine rotation is 115.4 rpm. The minimum hydraulic head is 15.5 m, the maximum 31.5 m. Maximum flow per turbine is 360 m3/s.
The turbines were provided by Kværner, the generators by Brown, Boveri & Cie.
On the left side of the dam is a lock, which can handle ships with the following maximum properties: 83 m in length, 11.40 m on the beam, 3.8 m load-draught and a cargo capacity of 2500 tons.