The Barrage Al Massira is Morocco’s second-largest dammed reservoir and lies in a semi-arid zone along the steep Oum Er-Rbia valley. This deep lake with winding edges, islets, and peninsulas is fed solely by the Oum Er-Rbia River. The reservoir serves as an important habitat for waterfowl, including rare and endangered species; during the summer, it supports around 20 waterbird species, with 15 nesting there. Notably, it hosts Africa’s only known nesting site for the black-headed gull (Chroicocephalus ridibundus), with 20 breeding pairs documented. Beyond its ecological importance, the reservoir plays a critical role in providing water for irrigation, drinking and fish farming, and in controlling floods and generating hydropower. Barrage Al Massira is Morocco’s most significant inland fishing site, producing 90 tons of fish annually from seven species, with official fishing permits capped at 12 per year. However, challenges such as illegal fishing, pollution, and disturbances during the nesting season emphasize the urgent need for effective conservation and management to safeguard its ecological and economic value.