This investigation was undertaken to determine the applicability of algae for the assessment of contamination level of water reservoirs with heavy metals. The alga Spirogyra sp. collected in the littoral zone of the Large Turawa Lake (artificial lake in Southern Poland) was used for the study. The concentrations of heavy metals accumulated in the alga inhabiting a flow-through water basin of the Large Turawa Lake were found to correlate with sources of these metals, such as benthic sediments and contaminated watercourses. The highest concentrations of metals were found in alga samples collected at the outlet of the lake: c _Mn = 12330 mg/kg dry mass, c _Fe = 15059 mg/kg d.m., c _Cu = 47.5 mg/kg d.m., c _Zn = 1411 mg/kg d.m., c _Cd = 108.8 mg/kg d.m., and c _Pb = 684 mg/kg d.m. The metals originated from benthic sediments (sapropelic mud) deposited close to the outlet of the lake. Statistically significant differences in the concentrations of cadmium accumulated in the alga were found between samples from the sites, where cadmium occurred in sandy sediments (max. 27.6 mg/kg d.m.), and samples from the sites located far from the contaminated sediments (max. 12.8 mg/kg d.m.).