In 1925 was created the Hidro-Eléctrica do Alto Alentejo, enterprise with the goal of making energy cheaper not just for some people in the District, but also for the industry. Ing. Custódio Nunes, born in Póvoa e Meadas, could quite early understand the necessity of using the large rushing streams that in the Winter enlarged the flow of Ribeira de Nisa (river), transforming that force into electrical energy.

In the short time of just two years the dam wall was finished, with a lightly convex directrix, trapezoidal section, 28,5m maximum hight and a development of 360m, what creates a flood surface, at the Full Storage Level, from 236ha and 6km length.

The Barragem (dam) of Póvoa e Meadas arose in 1927, it was the first and the biggest hydroelectric $nbsp;plant in Portugal. It is situated ca. 11km northeast of Castelo de Vide in the parishes of S. João Baptista and S. Tiago Maior, it is supported by the longest river in the Municipality of Castelo de Vide, and also by several little streams.

The bed of the dam is characterized by granitic rocks what creates a very beautiful and unique landscape. Around the dam there are several oak groves. In the south there are some arable crops and, northeast, the green spot of eucalyptus and pines is an exception in this ensemble.

The dam is classified to "Limited Use", this means that for secondary uses of the water there are the following rules:

- Professional fishing is forbidden;

- It is free to catch red crayfish from Louisiana and also sport fishing of all exotic species in all the dam, except the bass. Bass fishing is regulated by specific legislation;

- It is forbiden to hunt at the beach, in touristic areas, protected areas and involving areas and by the water;

- Intensive aquaculture is forbidden.

- It isforbiden the use of motorboats, except for emergency rescue boats.

- Installation of pontoons or floating rafts, for boat mooring or support by the use of the dam, may just be authorized to touristic enterprises, to concessionaires of water leisure areas, to Municipalities, and the activities must be considered a public service.