After outfoxing Egypt on the diplomatic stage for more than a decade, Ethiopia is set to officially inaugurate one of the world's biggest dams on a tributary of the River Nile, burying a colonial-era treaty that saw the UK guarantee the North African nation the lion's share of its water.
The dam - built on the Blue Nile at a cost of about $5bn (£3.7bn), with a reservoir roughly the size of Greater London - has led to a surge in Ethiopian nationalism, uniting a nation often polarised along ethnic lines and mired in conflict.
Ethiopians may disagree on how to eat injera [their staple food], but they agree on the dam, Moses Chrispus Okello, an analyst with the South Africa-based Institute for Security Studies think-tank, told the BBC.
They do not see it as a pile of concrete in the middle of a river, but as a monument of their achievement because Ethiopians, both at home and in the diaspora, funded the dam's construction. There were waves and waves of appeals for contributions when construction started in 2011.
Named the Grand Ethiopian Renaissance Dam (Gerd), it is Africa's largest hydro-electric plant, raising hopes that it will meet the energy needs of the 135 million-strong population while giving the country 'energy hegemony' and boosting foreign currency earnings.
Ethiopia plans to sell electricity to neighbouring countries such as Kenya and Djibouti, with ambitions of building a transmission network across the Red Sea to reach Middle Eastern states.
However, for Egypt, the dam represents a direct threat to its water security, with concerns that water shortages could be exacerbated as the dam stores significant amounts of water that would traditionally flow to Egypt.
Egypt, predominantly a desert nation, relies almost entirely on the Nile, raising fears among its population regarding agricultural impacts and water availability. Egyptian officials have voiced strong opposition, stating that water security is a 'red line' for the country.
Despite threats and diplomatic pressures from Egypt, Ethiopia remains firm in its commitment to the dam, highlighting its need for energy development and growth for its impoverished population.
As celebrations in Ethiopia continue around this momentous achievement, the geopolitical implications of the Gerd loom large, fostering concerns over regional tensions and future negotiations between the two nations.