The Biala River Wetland in southern Poland has received mine water discharges containing high concentrations of zinc and lead for about 400 years, providing a rare opportunity to study long-term filtration of heavy metals by a wetland. Application of the wetlands for treatment of industrial wastewater and as a sink for pollutants is questioned by some professionals. Among their concerns is a problem of long-term tolerance of wetland plants to high concentrations of heavy metals in their tissues as well as in soil. This chapter presents the results of investigations of these heavy metals in the wetland and the rates of filtration.