The effectiveness of self-restoration for two small mine impacted shield lakes.

摘要

Two lakes in the Whitesand Watershed, Cleaver and Horneblende, were impacted by mining and milling activities that occurred at the headwaters for over a decade. These lakes, both exhibiting varying degrees of meromixis, were examined for their water quality and potential for natural restoration for brook trout habitat. Detailed sampling took place from October 1999 to March 2001.; With the termination of discharge from the mine in the fall of 1999, the lakes were able to experience relaxation of input from the mine. Cleaver Lake had a well established monimolimnion at 6m, which dropped to 7m during fall turnover in 2000, although no discernable trend in water quality could be detected. An experiment was conducted with Cleaver lake sediments to determine the effect of sediment aeration. No release of zinc, copper, iron, or manganese was detected in aerated sediment samples. Horneblende Lake had a much weaker chemocline that eroded continually throughout the study period. There were more significant reductions in metals, sulphate, calcium, and conductivity, reflecting the eroding stratification. With the improvement of meromixis and stability of zinc levels, brook trout sustainability in Cleaver Lake appears possible.