Construction began in 1975, when the Ghana government commissioned Taysec, a British engineering company, to build a dam that would break the region's dependence on seasonal rainfall. The Kassena-Nankana District, stretching across the flat savanna south of the Burkina Faso border, had rich soil but unpredictable water. Farmers planted when the rains came and waited when they did not. The dam took a full decade to complete, finally becoming operational in 1985. To manage the ambitious irrigation scheme, the government established the Irrigation Company of Upper Region, known as ICOUR, which would oversee water distribution, canal maintenance, and the coordination of roughly 2,500 smallholder farmers spread across nine villages, each cultivating an average of just 0.6 hectares.

The dam's impact was transformative. Seven communities that had depended on a single growing season suddenly had water year-round. Rice became the dominant crop -- by recent estimates, it covers roughly 98 percent of the irrigated land -- but farmers also grow tomatoes, soybeans, onions, peppers, and leafy vegetables across the scheme's canal network. The irrigation infrastructure includes a main gravity canal lined with concrete slabs, feeding a network of smaller channels that distribute water across the fields. For families accustomed to food scarcity during the long dry season, the dam represented a fundamental shift: farming became a year-round livelihood rather than a seasonal gamble. Livelihoods improved. Nutrition improved. The calculus of survival in the Upper East changed.

Behind the dam, an artificial lake formed that became something the engineers had not planned for: a bird habitat. The reservoir's shallow margins and seasonal water-level fluctuations created conditions that attracted wading birds and waterfowl, adding an ecological dimension to what was designed as pure agricultural infrastructure. But the lake also brought a less welcome inhabitant. The still, warm waters proved ideal breeding ground for the schistosomiasis parasite, a waterborne organism that penetrates human skin on contact and lodges in the intestinal tract or bladder walls. Left untreated, it causes painful bleeding and can lead to sterility. For farmers and children who work and play in the irrigation canals, the parasite became an unavoidable cost of the dam's benefits -- a reminder that engineering solutions in tropical environments rarely come without biological complications.

By 2008, decades of use had degraded the main canal's concrete lining, and the Ghana government undertook rehabilitation with funding from the World Bank and USAID through the Ghana Commercial Agriculture Project. The investment reflected the dam's continued strategic importance: Tono is not just a local irrigation project but one of the largest agricultural dams in all of West Africa. For the smallholder farmers of Kassena-Nankana, the dam remains the foundation of economic life. Their plots are small, their margins thin, but the water flows reliably, and the rice grows. In a region where climate uncertainty defined existence for generations, that reliability is worth more than any statistic can convey.