Coeur d’Alene Lake (CDAL) is heavily contaminated with toxic metals, such as As, Cu, Cd, Fe, Mn, Pb, and Zn, from legacy mining practices. Differences in mineral phase association and the role of diagenesis have led to uncertainty regarding metal fate and transport, especially if CDAL transitions from its mesotrophic status to a eutrophic state. While Zn inhibition of phytoplankton is believed to reduce the probability of an algae-induced eutrophic event, alterations in lakewater chemistry, increased water temperature with climate change, or reduction in the input of Zn from planned remediation could result in increased bioproductivity. An increase in algae production may induce algal blooms and the potential for additional metal release from contaminated sediments to the water column. The primary objective of this study was to assess the effect of anaerobic conditions (control) and addition of algal biomass (treatment) in sediment porewater and dissolved metal flux across the sediment-water interface (SWI). This experiment was conducted as a benchtop examination of metal mobility using cores collected from the CDAL lake bottom, which were incubated for eight weeks at 5ºC under a N2 atmosphere with an overlying water column. Selected control and treatment cores were sacrificially sampled every two weeks for analysis of metals, anions, pH, and ORP of porewater/overlying water and metal concentrations of separated sediments. In control and treatment cores, all metals (As, Cu, Cd, Fe, Mn, Zn), except Pb, were released into the SWI and overlying water over the course of the experiment. Treatment significantly increased the rate of release for As, Mn, Fe, and Cu (p<0.05), but not Zn and Cd. Although, there was a significant interaction between treatment and time for As and Fe (p <0.05). Flux ratios (treatment/control) for As (10.4 ± 0.7), Cd (1.7 ± 0.2), Cu (1.8 ± 0.3), Fe (252.0 ± 142.6), Mn (3.1 ± 0.2), Pb (4.1 ± 2.4), and Zn (0.7 ± 0.7) demonstrate that treatment had a substantial impact on the release and mobility of most metals. Metal concentrations in porewater below 3 cm did not appear to be influenced by treatment as indicated by a fluoride tracer that suggested limited permeability and diffusion of metals from lower layers. Results of the study indicate that eutrophic conditions would induce further metal mobility and decrease water quality in CDAL, especially for redox active metals, such as As, Mn, and Fe. Future remediation activities to decrease Zn input to CDAL will need to consider the potential impact of increased phytoplankton production on metal release from the sediments to minimize negative impacts associated with possible eutrophication of CDAL.