British Columbia Mine Reclamation Symposium

Development of an environmental effects monitoring program for the Eskay Creek Mine Raggett, E. Jolene; Bailey, Howard C.; Murphy, P. M.; Chapman, Peter M.

Abstract

Environmental Effects Monitoring (EEM) is an important component of metal mining operations which is used to determine if mine discharges are causing adverse effects to the aquatic receiving environment. In 1997, prior to the publication of Environment Canada's draft EEM guidance document, Homestake Canada, Inc. requested that EVS Environment Consultants (EVS) implement an EEM Program for the Eskay Creek Mine. Mining operations at this site result in the production of mine water, waste rock and tailings, which Homestake is authorized to discharge. The Eskay Creek Mine EEM program was designed to assess whether mine discharges cause exceedances of the BC Freshwater Aquatic Life Criteria in the receiving environment and/or adverse effects to resident aquatic biota. The program includes monitoring of water, sediment, periphyton, benthic invertebrate communities, and bioaccumulation studies (no fish are present in the creeks draining the mine site). Results of the EEM studies show that water and sediment chemistry appear to be minimally impacted by mine discharges, with several criteria exceedances due to naturally high metal concentrations from the mineral rich drainage. Elevated sediment metal concentrations are present in Ketchum Creek downstream of mine discharges. However, the benthic invertebrate community increases in both abundance and number of taxa, which suggests that metals are not adversely affecting the community. Overall, discharges from the mine do not appear to be impacting sediment or water quality in the Unuk River as this system contains naturally high metals concentrations due to the mineralized drainage. Following the conclusion of each annual EEM program, results are reviewed to ensure that the objectives of the program are being met. This program is an excellent example of how science and adaptive management can be used to help mines achieve their environmental monitoring goals.

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