Fish Habitat At Horizon Oil Sands – Horizon Lake Monitoring

Canadian Natural Resources Limited is developing the Horizon Oil Sands Project, which includes creating Wapan Sakahikan (Horizon Lake) as a compensation lake to offset fish habitat losses caused by the project. The lake, located about 60 km north of Fort McMurray in the Tar River watershed, is designed with an average depth of 7.2 m, a maximum depth of 23.0 m, and a surface area of 76.7 ha, supporting species like Arctic grayling, northern pike, and burbot. Golder Associates was contracted to design and implement a monitoring program to track ecosystem establishment during the first five years and beyond. Initial monitoring began in 2008 during lake filling, and by 2010, methods were expanded to improve species composition data and benthic invertebrate representation, with sampling frequency adjusted over time. The compensation lake aims to meet Fisheries Act requirements by achieving a habitat productivity ratio of 2:1 based on fish biomass.

The 2010 Horizon Lake monitoring report evaluated fish habitat development through assessments of water quality, sediment, plankton, benthic invertebrates, and macrophytes. Water quality generally met guidelines, though some parameters like phenolics and mercury exceeded limits, and seasonal variability in chlorophyll-a and nutrients was observed. Sediment samples contained arsenic and other compounds above guidelines, while plankton biomass peaked in summer but showed instability in community composition, indicating an unsettled ecosystem. Benthic invertebrate abundance increased compared to previous years, though diversity remained low, and macrophyte colonization was limited but beginning to establish. Photographic records confirmed shoreline vegetation recovery, primarily grasses, along disturbed areas.