Open Collections

Abstract

The Copper Mountain Mine (CMM) is an open-pit facility that began operations in the 1960s. The mine is permitted to discharge mine contact water to Wolfe Creek, which flows through a series of lakes (Lorne Lake, Jackson Lake, Issitz Lake, and Wolfe Lake) prior to entering the Similkameen River. Anecdotal observations have suggested increasing primary productivity in these lakes in recent years. An evaluation of baseline and historical trends is required to properly evaluate these conditions and differentiate between potential causes of nutrient enrichment (e.g., mining, agriculture, forestry, climate change, lake succession processes). Given long-term monitoring records are limited, Hatfield conducted a paleolimnological study for CMM to reconstruct historical ecological conditions in Lorne Lake (closest lake to the mine) and Wolfe Lake (furthest lake from the mine). Notably, lake sediments represent a rich archive of current and historical conditions in aquatic ecosystems. Over time, remains from organisms that have inhabited the system are deposited to and incorporated into the sediment record. Similarly, metals and organics tend to persist in sediments. These measures of sediment composition can provide valuable information on historical conditions and associated geological and anthropogenic influences. This paleolimnological approach used sediment coring to characterize these sediment properties and reconstruct past environmental conditions. Radiometric dating techniques were employed to assign dates to specific cross-sections of sediments within each core. Biological community remains (diatoms) in different sediment layers were then compared to the sediment chemical composition to infer conditions at the time of deposition. This approach enabled the sediment cores to be used to reconstruct natural baseline (pre-mine) conditions and track historical trends. By coupling biological and sediment chemistry data, results from the paleolimnological study represent a powerful tool for evaluating temporal trends in the ecological status of these lakes.