Mongabay: Brazil has given final go-ahead on a controversial dam on the Madeira river in the Amazon rainforest provided environmental conditions are met, reports the Associated Press. The $4 billion Jirau dam is expected to have a capacity of 3,300 megawatts of power when completed in 2013. It is one of two proposed dams for the Maderia in Rondonia state. The dams are expected to have the capacity to produce 6,450 megawatts of electricity, about 8 percent of Brazil’s demand, but have proven …