The “Piva” dam is located on the Piva River approximately 9 km upstream of Šćepan Polje. It is an arch dam, built in 1976. Its catchment area is 1,758 km2. The multiannual average river discharge is 74.4 m3/s.
The dam is one of the highest in Europe, with a height of 220 m and a length of 269 metres. Floods are discharged through a gated spillway (with a total capacity of 1,670 m3/s) and a mid-height outlet system (consisting of three outlets with a diameter of 2.5 m equipped with gates, located at half the height of the dam). The maximum capacity of the mid-height outlet is 373 m3/s.
There are two bottom outlets with a diameter of 2.5 m each and a maximum capacity of 240 m3/s.
The environmental flow is 25 m3/s or lower than this.
Due to specific topographical features, the powerhouse is located within the rock mass of the left river bank.
During the last few years a number of activities have been performed in order to improve the energy production and efficiency of this HPP. In addition to the activities related to the rehabilitation and modernization of the equipment, the possibility of riverbed dredging downstream of the dam spillway has been analysed. The main goal is to reduce the HPP tailwater level and thus to increase the head and the corresponding energy production of the HPP.
Pre-feasibility studies toward a HPP capacity increase were completed in 2011; the preliminary design will be finished in 2015, followed by the preparation of Tender Documents for rehabilitation of the generating units. Some of the electrical equipment has been rehabilitated in 2014.
The main characteristics of the Piva HPP with corresponding structures are presented below (Mm3 = millions of cubic metres; m.a.s.l = metres above sea level):
- Reservoir:
| Total volume | 880 Mm3 |
| Live volume | 790 Mm3 |
| Max. OEL | 677.7 m.a.s.l |
| Normal OEL | 675.0 m.a.s.l |
| Min. OEL | 632.0 m.a.s.l |
- Dam
| Type | Concrete arch |
| Crest elevation | 678.0 m.a.s.l |
| Height | 220.0 m |
- HPP
| Type | Underground |
| Max. head | 182.4 m |
| Rated head | 162.0 m |
| Min. head | 138.0 m |
| Installed flow | 240 m3/s |
| Installed power | 342 MW |
| Annual energy | 800 GWh |
| No of units | 3 |
| Type of turbine | Francis |
Source: IWRM Country Report for Montenegro, COWI, Stucky and Jaroslav Cerni Water Institute, 2017