Lake algal populations and physico-chemical changes after 14 years input of metallic mining wastes

A primarily lead-zinc-copper mine operating since May 1967 has continuously discharged heavy metal mine tailings into the south basin of Buttle Lake. Sampling of this previously undisturbed, wilderness park lake, during initial activities in 1966–1968 and again in 1980–1982 has indicated a pattern of change. Nutrient levels have remained stable while concentrations of heavy metals have greatly increased. This increase is largely due to acid generation and metals release to groundwater. Species of both periphyton and phytoplankton, known to be sensitive to heavy metals, have dramatically decreased in abundance. Other more tolerant forms such as Navicula cryptocephala, Synedra acus, Synedra filiformis and Cyclotella bodanica have subsequently increased in quantity. Additionally, species number and diversity have decreased throughout the lake while near the source of tailings effluent cell density was substantially lower.