NWT RESEARCH DATABASE

Regions: Dehcho Region

Tags: mercury, peatlands, methylmercury, permafrost thaw, Wildfire Effects, Indigenous guardians

Objective(s): To assess the effect of wildfires on changes in water quality in the Dehcho and South Slave region, which are affected by runoff from peatlands (containing e.g., organics, nutrients, and mercury/methylmercury), which are already experiencing increased permafrost thaw due to climate change.

Project Description: This licence has been issued for the scientific research application No. 5892. Objective summary: To assess the effect of wildfires on changes in water quality in the Dehcho and South Slave region, which are affected by runoff from peatlands (containing e.g., organics, nutrients, and mercury/methylmercury), which are already experiencing increased permafrost thaw due to climate change. Synopsis: The impacts of the recent wildfires in the Dehcho and South Slave region on runoff generation and water quality will be studied. The region consists of widespread peatlands that are experiencing rapid permafrost thaw due to climate change, which also has the potential to affect hydrology and water quality (e.g., DOM, nutrients, and mercury/methylmercury).The region has vast stores of mercury accumulated in organic wetland soils, and there is a risk that disturbances such as permafrost thaw, wildfire, and beaver activity will increase the downstream mobility of mercury and thus its incorporation into food webs. The role of wetlands as primary sources of methylmercury will be particularly assessed, especially how wetland disturbances may affect downstream loadings. The goal is to study runoff generation, hydrological connectivity, and water quality at two different scales within the study region; a local study in a small (150 km2) headwater basin at the Scotty Creek Research Station (SCRS) and a regional water quality study of 13 watersheds (150-2,000 km2) located between Fort Simpson, Hay River, and the NWT/AB border. The combination of work at different scales will improve process-level understanding of how wildfire affects runoff generation and water quality at smaller scales, as well as a broader perspective on how these processes influence patterns at larger catchment scales. The knowledge from this project will help decision makers plan climate change adaptation initiatives when assessing how climate change will impact water resources. The project team is uniquely positioned to address this topic given both their availability of pre-fire data which enables Before-After-Control-Impact (BACI) study designs, and their long-term experience working in the region, including long-term ongoing collaboration with local organizations. The study design will include monitoring of 13 streams and rivers across the Dehcho region, with sampling done in collaboration with the Aboriginal Aquatic Resources & Ocean Management (AAROM) Program, as well as the K'atl'odeeche First Nation. Additionally, wetland sites within the SCRC area will be further studied to assess how permafrost thaw wildfire, affects the biogeochemical processes responsible for mercury availability, methylmercury production, and their downstream mobility. These wetland sites will be located at already established research sites, to benefit from available site data and synergies with other ongoing projects. Our proposal will thus aim for the following objectives: Objective 1 (O1): Comparison of pre-and post-fire soil water chemistry and hydrological connectivity between different peatland types, Scotty Creek Research Station. To understand the large-scale water quality and hydrological changes that are anticipated in rivers across the Dehcho and South Slave, a process-based local study will be undertaken at the SCRS in collaboration with Li´i´dli?i? Ku´e´ First Nation (LKFN), who now owns and operates the station. In October 2022, a devastating late season wildfire swept across the headwaters of the Scotty Creek catchment. Fortunately, this site has 20 years of monitoring and study related to climate change and permafrost thaw on wetland hydrology, accumulating an impressive archive of pre-fire hydrologic data (e.g., water levels, snow depth, precipitation, temperature, permafrost temperature). Additionally, water quality data (e.g., major ions, DOC, mercury, and methylmercury) has been collected throughout the area that will serve as a unique comparison to post-fire conditions. Major ions and stable water isotopes have been sampled seasonally in these peatland complexes and monthly at the catchment outlet since 2021, which has partly been funded by CIMP226 led by Wright (2022-2025). The historical pre-fire data combined with the proposed post-fire data will help disentangle the cumulative impacts of climate change, permafrost thaw, and wildfire on water quality in wetland-dominated landscapes common throughout the region. Objective 2 (O2): Continued monitoring of stream water chemistry, including for watersheds affected by wildfire in 2022 and 2023. For the broad-scale study, we will continue ongoing collaborations with the Dehcho Aboriginal Aquatic Resources and Ocean Management (AAROM) and the K’atl’odeeche First Nation (KFN) to collect at least 6 samples per year from 13 creeks and rivers which cross the highways between Fort Simpson, Hay River, and the Alberta border. From west to east, these rivers are: Birch Creek, Poplar River, Scotty Creek, Jean Marie River, Samba Deh, Red Knife River, Axe Handle Creek, Kakisa, Hay River in Hay River, Escarpment Creek, Mink Creek, Swede Creek, and Hay River at 60th Parallel). Most of these creeks and rivers drain catchments with areas between 150 and 2000 km2, with the exception for the larger catchments of Sambaa Deh, Kakisa River, and Hay River. All these creeks and rivers have already been sampled by Olefeldt in collaboration with Dehcho AAROM and KFN, including analysis of nutrients, DOM, and Hg/MeHg, for between 2 and 6 years prior to the fires. The selected rivers include several which were significantly affected by wildfires in 2022 and 2023, including Scotty Creek, Jean Marie River, Redknife River, Escarpment Creek, Mink Creek. In addition, there will be similar sampling of an additional 10 creeks and rivers of similar size in Alberta during these years, with half of them also affected by wildfire (funded through Olefeldt project “Water Resources of the Hay River: A watershed in flux”). Available pre-fire data for all sites includes measurements of DOM, nutrients, and Hg/MeHg (dissolved and total), turbidity, and major cat and an-ions, with a lower number of samples with dissolved and total trace metals. These water quality parameters will continue to be measured over three years (2024-2026), which will allow for detection of any impact of wildfire, whether effects are sustained for several years after fire, and whether effects are most prominent during certain times of the year. Four streams (2 in the NWT [Scotty Creek and Escarpment Creek], and 2 in AB) are also to be monitored at a high frequency to assess temporal impacts on water chemistry. Field-deployed in-situ sensors are being used to collect high frequency data, along with three years of grab samples, will be used to better understand water quality variation throughout the year (snow melt, summer storms, etc.). Objective 3 (O3): Impact of wildfire on peatland runoff, with focus on runoff generation during snowmelt. The last objective is to assess the impacts of wildfire on runoff generation, both at the local and the catchment scale. A specific goal is to seek better understanding of how wildfires impact the timing and magnitude of runoff during snowmelt freshet. The length of the snowmelt period is a critical factor in determining how river ice will break up and/or decay. A short snowmelt period will rapidly convey snowmelt water to streams and rivers, which lifts the ice off of the riverbanks, and transports large chunks of ice downstream. This ice will eventually hit solid ice and form an ice jam, which dams the water behind it and can lead to significant out-of-bank flooding (dynamic breakup). A prolonged snowmelt period allows water to be slowly routed to river networks, reducing the runoff peak and allowing ice to thermally degrade in place (thermal breakup). Wildfires drastically change the landscape by lowering the albedo (through blackened trees) and increasing the amount of solar radiation (sunlight) that can reach the ground surface. Both factors can contribute to a much quicker snowmelt period and increase the chances of a dynamic breakup in the spring. Better understanding how wildfires impact the timing of spring snowmelt will thus provide important information to decision makers about how fires may impact potential flood conditions in the spring. All water sampling will follow established protocols. EPA method 1669 “Sampling ambient water for trace metals at EPA Water Quality Criteria Levels” will be followed – a “clean hands and dirty hands” technique for collecting water samples in the field for Hg and MeHg analysis. All Hg and MeHg analysis (both total and dissolved concentrations) will be done at the Biogeochemical Analytical Services Laboratory (BASL), which is accredited to ISO/IEC 17025 by the Canadian Association for Laboratory Accreditation. All creek, river, and shallow groundwater samples will additionally be analyzed at the Natural Resources Analytical Laboratory (NRAL, University of Alberta) using IC analysis for major anions (Cl-, Br-, SO42-, PO43-, NO3-, NO2-), ICP-OES analysis for Na, K, Ca, Mg, Al, Cu, Fe, Zn, Mn, and Li, combustion analysis for total organic carbon and total nitrogen, and DOM analysis of optical properties through UV-vis absorbance and fluorescence. Analysis of water isotopes will be done at the Wright lab at Queens University. The methodologies used will ensure comparability with data collected in previous projects and with routinely collected GNWT water quality datasets, necessary for detecting impacts of wildfire. The goals of this project were developed collaboratively with the K'atl'odeeche, and Li´i´dli?i? Ku´e´ First Nations. Community members expressed concerns about declining water quality potentially related to climate change and activities associated with resource extraction; their perspectives were critical during the site selection process. All monitoring results will be evaluated and communicated with local partners through workshops, meetings, and plain-language reports/pamphlets, or as directed by the communities. Key Stakeholders - Li´i´dli?i? Ku´e´ First Nation – Contact with Dieter Cazon, Executive Director. The LKFN operates the SCRS where O1 will be carried out, and has direct interests in the research on impacts of climate change and wildfires on water resources. LKFN Guardians will also be directly involved in the research, collecting data at the station. See attached letter of support. - K'atl'odeeche First Nation – Contact with Victoria St. Jean, Lands Manager. The KFN have expressed their interest in the proposed research and have been working with Olefeldt on a related project funded through the AB-NWT Bilateral transboundary agreement over the last two years. The KFN guardians will be directly involved in the research, collecting river samples between Hay River and the AB border. - The Dehcho Aboriginal Aquatic Resources and Oceans Management (AAROM) – Contact with Mike Low, Dehcho-AAROM Program Manager. The Dehcho AAROM has interests in understanding impacts of climate change and wildfire on water resources, and to establish baseline information on water quality. Mike Low is a member of the project team, and he has worked with Olefeldt the last four years on a previous CIMP project. For this project, the Dehcho AAROM will be sampling rivers west of Hay River. See attached letter of support. - Contact has been made with the Mackenzie Valley Land and Water Board – Heather Scott, Senior Technical Advisor. The Mackenzie Valley Land and Water Board sees value in the proposed research, as it can provide information on baseline conditions needed to assess impacts of new developments. The Mackenzie Valley Land and Water board however chose not to provide a letter of support for the project, in order to not appear to favor specific research projects. - Government of the Northwest Territories, Environment and Climate Change; Water Monitoring and Stewardship Division, supports the project, as indicated through the involvement of collaborator Dr. Ryan Connon. The fieldwork for this study will be conducted from: May 27 - October 31, 2024