This article provides a comparative environmental assessment for the Grand Ethiopian Renaissance Dam (GERD) learning from Itaipu dam experience. The article gives a full insight about the potential political and technical concerns that may affect the downstream countries as a result of the construction of GERD and proposed a solution and way forward for the negotiation based on joint collaboration perspective. Based on the analytical comparison conducted between GERD and Itaipu, the results showed that the total annual carbon dioxide (CO₂) emissions expected to be released from the GERD during the operation is 3,927 tCO₂eq, while other secondary emissions were estimated to be 16.17 tons, mainly of carbon monoxide and nitrogen oxides. Also, the ratio of power generation to reservoir capacity of the GERD was questionable, since Ethiopia has announced that the dam is built only for power generation and that there is no intention to utilize water from the dam reservoir. On the other side, the water quality - represented in turbidity, total suspended solids (TSS), dissolved oxygen (DO), total phosphorus (TP), and chemical oxygen demand (COD) - behind the GERD is expected to deteriorate dramatically. Also, an increase in total nitrogen (TN) is expected to occur depending on human activities. Accordingly, the article discussed thoughtfully the potential adverse impacts of the GERD on downstream countries and the possible mitigation options. The article also extended to discuss proposals for practical solutions that pave the road for joint collaboration between the three countries to achieve a transparent resolution and a fair resources utilization.