Barragem de Poilão

Barragem de Poilão
The front and the dam of Barragem de Poilão
Location	Santa Cruz, Santiago, Cape Verde
Coordinates	15°04′26″N 23°33′25″W / 15.074°N 23.557°W / 15.074; -23.557Coordinates: 15°04′26″N 23°33′25″W / 15.074°N 23.557°W / 15.074; -23.557
Type	Artificial Lake
Primary inflows	Ribeira Seca
Primary outflows	Ribeira Seca
Basin countries	Cape Verde
Max. length	1.23 km (0.76 mi)
Max. width	around 70 to 100 m (230 to 330 ft)
Surface area	around 18 m (59 ft)
Average depth	17 ha (42 acres)
Max. depth	26 m (85 ft)
Water volume	1.7 million cubic metres (0.0017 km3)

Barragem de Poilão is a reservoir located in the east central part of the island of Santiago, Cape Verde, mainly in the municipality of Santa Cruz but with the western part partly in São Lourenço dos Órgãos. It is located on the stream Ribeira Seca (Portuguese for "dry stream", as most of the year the stream flows without water). Both Ribeira Seca and Faveta are the island's longest rivers and could be the country's longest.

Several lagoons on Boa Vista and Maio islands were Cape Verde's only lakes before the construction of the reservoir. It is one of Cape Verde's largest lakes; the dam impounding it was the only concrete dam in Cape Verde until the construction of three other dams, two on the same island in 2013 and one on Santo Antão in 2014. The island has a dry climate with occasional torrential downpours. These cause the transport of large quantities of sediment into the reservoir and a study has found that without regular dredging, the storage capacity of the reservoir will be reduced by almost one half within seven years.

The artificial lake was laid out between the villages of Poilão and Lavada dos Orgãos with a fill dam that was completed in 2006. The reservoir has a capacity of 1.7 million cubic meters, making possible the drip irrigation of 64 hectares (160 acres) of land, corresponding to about 100 farms. The irrigation usage is 1.2 million cubic meters. The useful depth is 18 metres and the maximum depth is 26 metres. The length of the reservoir is 1235 metres, and the surface area is 17 hectares. The Poilão Hydrological Station is 120 metres (390 ft) downstream from the dam. The dam is built of masonry, with a core of reinforced concrete. The construction of the concrete dam was planned and paid for by China, at a cost of four million dollars. There is an information pavilion to the south of the artificial lake where some rare birds can be observed.