NWT RESEARCH DATABASE

Regions: Dehcho Region, South Slave Region

Tags: physical sciences, contaminants, mercury, water quality, fish habitat, sediment quality, fish abundance

Objective(s): To monitor the trends and fluctuations of the aquatic environment along the riparian zones within the Taltson River from Nonacho Lake to Twin Gorges facility, including fish species composition and condition, vegetative communities, and habitat characteristics.

Project Description: This licence has been issued for the scientific research application No.4565. The objective of this project is to conduct Aquatic Effects Monitoring. This will include three parts: 1) Riparian Habitat and Fish Usage Assessment. This is a study to monitor the trends and fluctuations of the aquatic environment along the riparian zones within the Taltson River from Nonacho Lake to Twin Gorges facility, including fish species composition and condition, vegetative communities, and habitat characteristics. 2) Mercury in Sediment and Fish Flesh Monitoring. This study monitors mercury concentrations in sediment and fish flesh within the Taltson River from Nonacho Lake to Twin Gorges facility. To monitor mercury levels in fish and sediment sampling efforts focus on fish populations within Trudel Creek, Nonacho Lake and Rutledge Lake (control lake). 3) Sediment and Erosion Monitoring. As per Mackenzie Valley Land and Water Board (MVLWB) directives Northwest Territories Power Corporation (NTPC) must install continuous turbidity loggers in Trudel Creek and Taltson Tailrace to collect data for the 2019 open water season. An assessment at each established erosion monitoring station must be completed to provide a qualitative analysis of erosion rates. The research team will collect data within the Taltson River from Nonacho Lake to Twin Gorges facility, on fish species composition and condition, vegetative communities, and habitat characteristics. Mercury concentration levels will be collected within sediment and fish flesh within Nonacho Lake, Trudel Creek and Rutledge Lake. Trends in mercury concentrations will be identified. The team will determine if mercury concentrations in fish are above guidelines for human consumption and for the protection of aquatic life; and conduct an internal examination of sacrificed fish for parasites, stomach content analysis, aging structures and stable isotope analysis. The team will obtain continuous turbidity data on 15 minute intervals in Trudel Creek and Taltson Tailrace for one open water season. Erosion monitoring will be conducted at previously established monitoring stations to provide a qualitative analysis of erosion rates. Aerial imaging will be assessed to help characterize and determine erosion rates. A number of fish will be captured at various sampling locations, for measurements of various parameters such as length, weight and species identification. Fish will be captured using a number of methods including gill nets, angling, electrofishing and seine netting. A subset of the captured fish will be sacrificed and submitted to appropriate and accredited analytical lab to measure the level of mercury in their tissue. As part of the Project NTPC will be also conducting traditional knowledge surveys and/or interviews with interested parties. Water quality samples will be taken and aquatic vegetation characteristics will be recorded. Continuous turbidity loggers will be installed in the tailrace of the Taltson Facility and in Trudel Creek and collect data throughout the open water season of 2019. Erosion pins will be monitored and aerial imagery will be assessed for erosion rates. The results will be submitted to the MVLWB which will then post all results online on the MVLWB Public Registry. The fieldwork for this study will be conducted from August 30, 2019 to September 30, 2019.