Food chain alteration with heavy metals is one of the most important concerns in public health and food safety. This research reports the first monitoring of heavy metals in the Adolfo Ruiz Cortines dam in Alamos, municipality of Sonora, Mexico. Concentrations of Arsenic (As), Lead (Pb), Mercury (Hg) and Copper (Cu) were analyzed by atomic absorption spectrophotometry coupled to the hydride generation system. A health risk assessment was carried out calculating cumulative doses of As and Pb in tap water, Oreochromis niloticus (known as tilapia) and dam sediments. The results of this research reveal that themost important source of arsenic in humans is Oreochromis niloticus and for lead it is the consumption of tap water. Children are the most affected population, reaching a cumulative risk index for exposure to Pb of HIc = 3.30 and for As of HIc = 7.35. This study estimated that communities close to Adolfo Ruiz Cortines dam, present a potential health risk due to the consumption of O. niloticus, tap water and dam sediments contaminated with Pb and As.