New technologies are experienced to clean contaminated sites. Bioremediation is one of the methods considered for cleaning abandoned mine sites, since most of the time it is less costly and environmentally friendly. The Berkeley Pit lake is one of these mine sites, part of the largest Superfund site in the United States, with a very low pH (2.7) and high concentration of heavy metals. Bioremediation is considered a possibility to clean this acidic lake, since organisms were found to live in this very harsh environment with a low pH, high concentration of heavy metals and undetectable organic carbon. Six species of algae and several species of yeast, bacteria, fungi, protozoans and an insect were found to live in Berkeley Pit water. Most of the studies for bioremediation potential were focused on five species of algae: Chromulina freiburgensis Dofl.,Chlorella vulgaris Beijerinck,Chlorella ellipsoidea Gernek Chlamydomonas acidophila Negoro and Euglena mutabilis Schmitz. These algae are photosynthetic and do not need organic carbon, but can become a source of organic carbon and may become the base of a trophic system, which seem to actually exist in Berkeley Pit in a simple form-algae seem to sustain the bacteria, fungi, yeast , protozoans comunities. Studies have been done to determine the nitrogen and phosphorus requirements to insure the best algal growth in the Berkeley pit water conditions and to determine the best bioremediator of the five species of algae considered for their bioremediation potential. Further research will focuse on the dynamic of the sorption process (which is the capacity of algae of retaining metals on their surface or inside the cell) and to determine what is the contribution of bacteria populations in the sorption process.

Key words: Montana Tech