Are dams actually helping communities?

Dams are barriers that stop the flowing of water in rivers and streams created by humans, to use as a reservoir. However we are not really sure that the people are being benified by them, that's why I created an infography which states the advantages and disadvantages of it.

One example is of a dam is the Salto Grande Dam shared between Uruguay and Argentina, located in the Uruguay River between Salto (Uruguay) and Concordia (Argentina). Its construction began the 1^st of April 1974 and it opened in 1979 as a reservoir which produce hydroelectric power. According with the official Salto Grande's page, this reservoir "produces energy in a clean, safe and economic way, through the use of a renewable resource, contributing to the economic and social development of the countries, and conserving our environment for future generations, within a framework of occupational health and safety that complies with the current legislation in both countries", it not only generates electicity for both  communities, but also "strengthen the communication between the Salto Grande localities and create development conditions for the communities, the environment and the workers of the organization", besides it "Collaborates in education, culture, health, sports and tourism projects. Carries out direct actions to protect the environment and responsible consumption of energy". As what regards to the people "the public's good initiatives, carried out by municipalities or civil society, receive, in many cases, the advice of professionals from Salto Grande."

Despite the fact that the dam has great goals, the lack of coordination among the countries, and the lack of a shared water resources management policy is costing some reservoirs  to dry, like happened in 2006 in Iguassu. Now the Salto Grande Dam is running out of water because of he "lack of rain", meanwhile some dams locate in Brazil are stocking water.