Heavy metal pollution in freshwater ecosystems poses a critical environmental and public health concern, particularly in semi-arid regions where reservoirs serve as primary sources of water for human consumption, agriculture, and biodiversity conservation. The Paraíba do Norte Basin, northeastern Brazil, harbors multiple reservoirs exposed to anthropogenic pressures, including agricultural runoff, untreated effluents, and climate-driven hydrological fluctuations. However, the extent of heavy metal contamination in these reservoirs remains underexplored. Here, we analyze water samples collected from eight reservoirs, Poções, Camalaú, Boqueirão, Acauã, Araçagi, Taperoá, Sumé, and Cordeiro, assessing the concentrations of iron, lead, aluminum, zinc, and other trace metals across different depths and sampling locations. Water samples were obtained at three distinct points per reservoir, lentic (near the dam), transition (mid-reservoir), and lotic (riverine inflow), and analyzed using inductively coupled plasma optical emission spectrometry. Our results reveal high spatial and depth-related variability in metal concentrations. Aluminum levels reached up to 49.47 ppb in surface waters, while lead concentrations, though lower, exceeded 1.8 ppb in some reservoirs, raising concerns about bioaccumulation. Iron levels were particularly elevated in Boqueirão and Acauã, suggesting strong geogenic influences and possible mobilization under anoxic conditions. Compared to historical data, our findings indicate a persistent contamination trend, likely exacerbated by deforestation, land-use change, and fluctuations in hydrological regimes. These findings underscore the urgent need for improved watershed management strategies, including sediment control, pollution mitigation, and regular monitoring to ensure safe water quality for human use and ecosystem health. Further research should assess the bioavailability of these metals and their potential impacts on aquatic food webs and drinking water safety.