Salmon depend on healthy and resilient watersheds but the increasing amount of drought and flood events in the Nicola Region coupled with the growing impacts of climate change are negatively impacting their spawning habitat and freshwater systems. In 2024, Raincoast Conservation Foundation (Raincoast), in partnership with Scw’exmx Tribal Council (STC), and Citxw Nlaka’pamux Assembly (CNA), completed a project assessing environmental flow needs and mapping thermal refuges in the Coldwater River, in the Nicola Valley, on the traditional territory of the Nlaka’pamux and Syilx Nations, near Merritt, BC.
The Coldwater River is a snow-dominated watershed, meaning most of the water in the river system comes from snowmelt each spring. With drier winters and hotter summers, the river’s summer flow is decreasing each year, reducing salmon habitat. In addition, climate emergencies affect the health of the Coldwater River – a record drought in 2025 led to significant pre-spawn mortality of Chinook salmon.
Raincoast, STC, and CNA mapped streamflow levels throughout the Coldwater River to generate data that is now being used to inform habitat restoration, drought management, and other watershed decisions to support the long-term resiliency of the Chinook salmon who spawn in the Coldwater River. Chinook salmon are a culturally significant species for the local Nlaka’pamux and Syilx First Nations, and this unique population of salmon is a key food source for the endangered southern resident killer whale population in the Salish Sea.
Building resiliency for salmon
This project concluded in 2024 and fulfilled two key objectives:
- Use methodology developed by the Okanagan Nation Alliance to determine Environmental Flow Needs (flow requirements of a healthy stream ecosystem) for salmon spawning and rearing creeks in the Nicola River Watershed. This includes conducting field-based assessments of stream flows, aquatic habitat, and riparian habitat coupled with interviews with Indigenous Knowledge-holders.
- Use the data collected to guide water conservation, drought response, water allocation, habitat restoration, and watershed governance.
Identifying cold water refugia
Now, in 2026, data that was collected from the 2024 environmental flows project is being used to guide conservation decisions. These decisions will help ensure that salmon can continue to thrive and return to their historical spawning grounds. Despite its name, the Coldwater River gets very hot. During the field season in 2024, the project team recorded multiple occurrences of stream temperatures above 24 C. Salmon rely on cold water and any temperatures above 22 C can be potentially lethal for both juveniles and adults.
Since the conclusion of the 2024 environmental flow needs project, Raincoast has expanded their work to identify thermal refugia for salmon within the Coldwater River. Thermal refugia are micro-habitats within a stream that are significantly cooler than the surrounding water and they play a vital role in allowing salmon to escape potentially lethal temperatures during the summer.
“There’s lots of things that happen outside in the ocean that we don’t have a ton of control of, but… being able to work in the watershed here to do work that actually is impactful [is] super powerful.”
– Nathan Lustig, Fisheries Biologist, Scw’exmx Tribal Council (Finding thermal refuges for salmon in the Coldwater River)
Building on the data collected in the 2024 project, Raincoast, STC, and CNA are using drone-based thermal imaging to map potential sites of thermal refuge. This is followed by ground-truthing the imaging through measuring stream temperatures and assessing the whole area for its viability as long-term salmon habitat. They are also conducting snorkel surveys in the river to assess the type and quantity of fish taking advantage of these thermal refuges. The final goal of this project is to build an inventory of thermal refugia sites along the Coldwater River with data on habitat characteristics, fish population, and potential threats to their long-term vitality.
“These pockets of cold water that are naturally occurring are becoming more and more important for salmon to escape the extreme impacts of climate change and become more resilient over time as climate change continues to progress.”
– Auston Chhor, Salmon Habitat Biologist, Raincoast Conservation Foundation (Environmental flow needs in the Coldwater River)
Raincoast and its partners are hard at work to fulfill two key objectives for this project:
- Map the distribution of cold water refugia in the Coldwater River using a combination of drone-based thermal imaging and ground-based site visits.
- Study the behaviour and distribution of salmon in cold water refugia using snorkel surveys.
Looking ahead
Next steps for Raincoast, STC, and CNA include drafting a strategy to protect and enhance the thermal refugia sites for long-term use. Potential enhancement activities may include increasing the size of the thermal refugia or adding shading to limit solar radiation and keep temperatures down. Data from this project will also be used to inform climate adaptation, watershed governance, and projects that reestablish floodplain connectivity. This important work is actively contributing to salmon sustainability, providing a critical cultural species to the community and playing a key role in the watershed’s health for generations to come.
“I’m doing the guardian work to help protect the land because it’s not just for me, it’s for my grandkids as well. I want to do things to make things better for the next generation.”
– Crystal Swayze, nłeʔképmx Land Guardian, Citxw Nlaka’pamux Assembly (Environmental flow needs in the Coldwater River)