Fish Habitat At Horizon Oil Sands – Horizon Lake Monitoring

Canadian Natural Resources Limited is developing Horizon Lake as a permanent fish habitat to offset impacts from the Horizon Oil Sands project, meeting a 2:1 compensation ratio under the Fisheries Act. Located in the Tar River watershed, the lake spans 76.7 ha and supports species like Arctic grayling and northern pike. Monitoring began in 2008 and by Year 4 (2012), efforts expanded to estimate fish populations and maintain water quality and benthic invertebrate assessments. In Year 5 (2013), the program shifted toward fish production targets, using hydroacoustic surveys and a fish fence for tagging. Other monitoring continued with minor adjustments, including reduced sediment sampling frequency.

The aquatic monitoring program for Horizon Lake tracks its development as a productive fish habitat, including fish populations, water quality, plankton, benthic invertebrates, and macrophytes. In 2012, nine fish species were sampled with 18,593 fish captured, while in 2013, 10,997 fish were caught and the community showed signs of stabilization, though adult White Sucker continued to bioaccumulate mercury. Fish production in 2013 was estimated between 1.9 and 2.28 million grams per year, dominated by Longnose Sucker, White Sucker, and Lake Chub. Water quality remained generally stable across both years, with mesotrophic nutrient levels and some parameters exceeding guidelines, while plankton communities showed seasonal peaks and increasing diversity. Benthic invertebrates and macrophytes continued to expand, improving habitat complexity and supporting gradual progress toward a self-sustaining ecosystem.