The Nechako watershed

As the second largest sub-watershed of the Fraser River Basin, draining an area of 47,200 km² in the Interior Plateau of northern BC, the Nechako Watershed can be compared in size to the countries of Denmark (43,094 km²) and Estonia (45,227 km²), amongst others. The Nechako River mainstem originates from a chain of lakes and rivers draining the Coast Mountains onto the Interior Plateau to its confluence with the Fraser River in the city of Prince George (unceded Lheidli T’enneh territory). The Stuart River joins the Nechako River 92 km west of Prince George, contributing 14,600 km² from the Stuart-Takla sub-watershed with its own particular hydrological, climate, ecological and social features [18] p.727. Fig 2 depicts the entire Nechako watershed including First Nations communities and key settlements. Box 1 provides an overview of notably unique features of this watershed, with further detail being provided in the text.

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Fig 2. Map of the Nechako watershed (black outline) with identification of its main geographical features.

Note the confluence with the Fraser River at Prince George (unceded Lheidli T’enneh territory). Inset map shows the location of the Nechako within the larger Fraser River Basin (Freshwater Atlas Watersheds) in British Columbia (BC) (Provinces and Territories of Canada). Overlaid onto an ESRI basemap (ESRI World Light Gray Base) are information of a Digital Elevation Model for the Nechako Watershed (Digital Elevation Model for British Columbia—CDED—1:250,000).

https://doi.org/10.1371/journal.pwat.0000263.g002

While primarily continental in nature, the climate of the Nechako Watershed is moderated by the proximity of the Pacific Ocean, its main source of moisture for both rainfall and snowfall. Mean annual air temperature is 3.7°C and total annual precipitation is 601 mm of which about one third falls as snow [18]. Owing to the diverse landcover types and relief there are sharp spatial gradients in climatic variables across the basin. For instance, total annual precipitation reaches 1985 mm at Tahtsa Lake in the Coast Mountains while 113 km further east it totals 417 mm at Ootsa Lake/Skins Lake [19]. This area has experienced amplified climate change at about twice the global average rate [8]. While total annual precipitation has not changed appreciably over this period, a robust transition from snowfall to rainfall has been observed across the basin with marked declines in recent snowpack levels [20, 21].

The watershed is covered mostly by forests (~80%) with significant amounts of the land base covered by freshwater (~12%) and small areas converted to agricultural lands (2%) and even smaller areas converted to urban areas (~0.2%) [18]. Forest cover also provides a backdrop to the habitat and fire ecology features of the watershed that also provide important context to climate change impacts and water security within the Nechako Watershed. Based on 2016 depictions, the Nechako Watershed lies predominantly within the subboreal spruce biogeoclimatic zone, with minor areas of subboreal spruce-pine, Engelmann spruce and subalpine fir, and alpine tundra biogeoclimatic zones [22]. Fire has been a long-standing feature of the landscape in the Nechako Watershed [23], and continues to have a powerful impact on the lands, waters and communities in the region. There have been numerous large wildfires in the watershed, including the Shovel Lake wildfire in 2018 which burnt an area of 92,412 ha (924 km²) and in 2023 over 250,000 ha burnt in the watershed in a record-breaking wildfire season in BC [24–26].

Among the overview of features summarised in Box 1, the length, extent and range of human habitation, interaction with, and impacts on, the Nechako Watershed are essential components to understanding this important region of northern BC. The archeological record shows evidence of Indigenous peoples inhabiting the Nechako Watershed from 8000–10,000 years before present [27, 28], with semi-permanent habitation beginning to appear 4500 years ago [28]. As noted, the name of the Nechako River originates from Dakelh, the language of the Indigenous people whose unceded territories cover a large portion of the Nechako Watershed and the Central Interior of BC. Dakelh people are also known as Carrier peoples, and include groupings known as the Yinka Dene [29]. The word ‘koh’ in Dakelh is directly linked to waterways, evident in place-names throughout the watershed. Examples from the Yinka Dene Language Institute [30] and Carrier Sekani Tribal Council [31] include the Chilako River (Tsalakoh, beaver paw river), Fraser River (Lhtakoh, rivers within one another), Tachie River (Duzdlikoh, driftwood river), as well as in names such as Dakelh (people who “travel upon water”) and Ts’il Kaz Koh (formerly known as Burns Lake Band).

Although there is evidence of Indigenous and settler influence throughout the entire watershed, overall settlement sizes have remained small, which is reflected in a low population density. The estimate of current population in the Nechako Watershed, based on the 2021 census is approximately 108,000 people. Included in this count are 15 First Nations that total ~8000 people and ~13,000 people who live in unincorporated areas distributed across rural and remote areas of the Nechako Watershed [32]. Approximately 83,000 people live in five predominantly non-First Nations communities, with the largest being Prince George located downstream at the Fraser-Nechako confluence, with a population of 74,000 [8]. Excluding Prince George, the population density of the Nechako Watershed attains ~0.5 people/km². The inclusion of Prince George lifts this to 1.8 people/km². Each of these larger centres is situated either on the Nechako River or large lakes (Fraser and Stuart) that are part of the Nechako system.

The Nechako Watershed has undergone significant changes since colonization. Beginning in the late 1800’s European settlers began the process of converting forested areas to agricultural areas. In 1996, ~6% or 3100 km² were considered agricultural lands [18]. The most dramatic disturbance in terms of river flows and aquatic species was the construction in the 1950’s of the 98-m tall Kenney Dam on the mainstem Nechako River at its canyon upstream of its confluence with the Cheslatta River, creating the 922 km² Nechako Reservoir encompassing many rivers and lakes including Tahtsa Lake. The purpose of the dam and resulting reservoir was to redirect water westwards against the hydraulic gradient to power an aluminium smelter built in the planned community of Kitimat on BC’s Pacific Coast [33]. The 960 MW Kemano Powerhouse was built deep inside Mt. Dubrose within the Coast Mountains and connected to Tahtsa Lake in the headwaters of the Nechako Watershed by a 16 km tunnel. It was designed to provide a reliable and inexpensive source of hydropower to meet Canada’s growing demand for aluminium [33]. Since Kenney Dam became operational in 1954, water releases to the lower Nechako River have been controlled at the Skins Lake Spillway allowing management of Nechako Reservoir levels to optimize inter-basin water transfers to the Kemano Powerhouse and its production of hydroelectricity. There is no water release facility at Kenney Dam and it forms a migration barrier for aquatic species between the upper and lower Nechako River. The management of the Nechako Reservoir is associated with an in-perpetuity water right governed by companies who own and run the Kenney Dam, Kemano Powerhouse and the BC Works Aluminium Smelter at Kitimat, including Alcan until 2007, subsequently Rio Tinto Alcan (2007–2015), and now Rio Tinto.

The construction and management of the Kenney Dam, reservoir and associated spillway have created a complex array of upstream, downstream and inter-basin impacts, that can be understood as a ‘cascade’ of direct and indirect social and ecological effects, with ongoing impacts throughout the watershed [34]. Hydrographs post-regulation for the upper Nechako River exhibit marked departures from pre-regulation patterns, with highly regular flows year-round except for a one-month period in summer when ecological flows are released from the Nechako Reservoir; further details regarding these changes are presented later.

Of particular note in any reflection on the Kenney Dam and impacts on ecosystems, communities and well-being in the Nechako Watershed are profound and ongoing impacts on First Nations. This includes the displacement of Cheslatta Carrier Nation [33, 35–37], and growing recognition of ongoing impact experienced on other downstream First Nations communities. The gravity of this situation is indicated by the court case (and subsequent appeal) against Rio Tinto Alcan Inc. that has been led by the Saik’uz First Nation and Stellat’en First Nation since 2010, with the goal to “reinstate the functional flows that make up the natural flow regime of the Nechako River.” [38]. In February 2024, the BC court of appeal [39] held that: “Canada and BC have a fiduciary duty to protect the Saik’uz and Stellat’en First Nations’ Aboriginal right to fish on the Nechako River, including by ensuring the water allocation and flow regime is managed in a manner consistent with the Crown’s obligations under section 35 of the Constitution” [40], creating legal recognition of the ongoing impacts of the Kenney Dam on the First Nations’ established fishing right [39, 41].

In addition to the waterway changes throughout the Nechako, land clearing, particularly in the Vanderhoof area, has increased significantly due to the influx of offshore investment in ranching operations for the purposes of exporting forage crops to Asia. Forestry has historically been the primary economic driver and one of the major forces exerting change on the landscape in the Nechako Watershed. Large scale industrial forestry, as found in the Nechako, has accelerated in the recent past, including salvage harvesting due to mountain pine beetle (Dendroctonus ponderosae) outbreaks. The interplay of climate change, mountain pine beetle impacts, changing commodity prices and expanding wildfires among other factors, create ongoing challenges for forestry and other resource development in the region, with far-reaching biophysical and socio-economic impacts [7, 8, 42–46].

The BCMine Information site [47] identifies the Blackwater Gold mine proposed in the Nechako Watershed, located south of Vanderhoof. In addition, two mines—Huckleberry (a copper mine) and Endako (a molybdenum mine)–are on long-term care and maintenance status due to weakness in commodity prices; and one mine—Pinchi (a mercury mine) which closed in 1975, is under long-term maintenance after a decommissioning and reclamation process (2010–2013) [47].

Although far from a complete appraisal of the changing natural, historical, social and economic features of the Nechako, this overview of key features is intended to provide background to the importance of this system across environment, community and well-being concerns. This also provides the context for the initial phases of work conducted by the IWRG between 2014–2023, and the need for ongoing commitment to understanding this important system in ways that go beyond what is possible through single disciplinary or other knowledge perspectives.

Confluence and connections: Rationale for a case-study of integrated watershed research in the Nechako

From the nested context described above—ranging from global and provincial calls for integrative approaches to water(shed) security and related research, to the compelling and unique features of the Nechako Watershed—we have identified four key factors that influenced the formation of the IWRG as a ‘case study’ in integrated watershed research.

A first important influence on the IWRG team orientation to this system was influenced by the fact that the UNBC campus is situated on unceded Lheidli T’enneh territory, 10 km west of the confluence of the Nechako and Fraser Rivers, and therefore physically and socially ‘embedded’ in the relationship between the Nechako Watershed and Fraser River Basin. Despite the obvious proximity, there had not, to the emerging team’s knowledge, been an ongoing cross-disciplinary collaboration focused on the Nechako Watershed before, creating an obvious opportunity to progress UNBC’s ambition to be a University ‘in the north, for the north’ addressing issues of direct relevance to this important watershed, in ways that reflect calls for ‘social accountability’ across the academy [48].

A second notable influence on the formation of our research team, is a shared interest in the interaction between themes such as water security, and an expanded research attention to the ‘integration imperative’ arising from the need to address cumulative impacts across land, water and community concerns [34, 36, 49]. Increasing attention to cumulative impacts also calls for more systemic understanding of complex watershed dynamics across driving forces, ecosystems, social systems, health and well-being (see [13]) and was a direct influence on the design of integrative work being developed in the watershed [7, 8]. Although not claiming to engage all UNBC researchers working in the Nechako Watershed, our core team expertise includes natural, social and health sciences.

A third and notable driver of the formation of the IWRG in the Nechako is the degree and extent of engagement of a variety of community groups with specific interest in deepened understanding in the watershed. This includes community efforts such as the multi-stakeholder Nechako Watershed Alliance in the early 2010’s, the formation of the Nechako Watershed Roundtable in 2015 [8, 50], collaborative restoration work of the Nechako Environment and Water Stewardship Society [51, 52] and early collaborations with the local Nechako Lakes School District (School District 91) and the regional health authority: Northern Health [51]. These points of local, within watershed, connection were also influenced by discussions and developments in relation to the provincial legislative context. This has included the release of the Water Sustainability Act [53], and global, national and provincial shifts leading to the BC Declaration of the Rights of Indigenous People Act [54]. This legislative context has provided further impetus to our work by recognising the role of First Nations, and other local communities and institutions in the development of strategies for watershed management.

A fourth factor that has continued to influence our approach to integrated watershed research is the ongoing and increasing awareness of the many other perspectives and orientations relevant to understanding different parts of the watershed, ranging from books and local narratives [55, 56], audio-visual materials and videos [35] and reflected in a range of student research [37, 57–62]. We see the recognition of other knowledges as an ongoing strength and necessary feature of any attempts at integrated watershed research, acknowledging that IWRG research does not seek any kind of ‘complete’ understanding but instead offers purposeful steps to harness different types of scholarship [48, 63, 64] and to deepen understanding of this important watershed and the implications for the health of communities and ecosystems that depend on it.

These points of context and connection created what can be seen as a confluence of efforts across different types of scholarship [63]. Although a starting point for IWRG team members is ongoing commitment to the ‘scholarship of discovery’ involving “the pursuit of inquiry and investigation in search of new knowledge” in their respective areas of expertise, our research team was also motivated by an interest in the ‘scholarship of integration’ seeking to make “connections across disciplines and, through this synthesis, advancing what we know” [48] (p.306). As our research progressed our team has also learned more about the potential for this work to inform the ‘scholarship of application’, ‘scholarship of engagement’, and—through partnerships across secondary and tertiary education sectors—the ‘scholarship of teaching and learning’ [48, 63].

This orientation to scholarship informed the guiding question that has informed our research: “How can integrated watershed research advance understanding and collaboration to address water security in the Nechako Watershed?”. This question also frames our case study approach, aligning with Creswell’s description, where: “A case study is a problem to be studied, which will reveal an in-depth understanding of a “case” or bounded system, which involves understanding an event, activity, process, or one or more individuals” [65] p.61.

Towards integrative watershed research: Braiding and learning across three themes

Over the course of a decade, our work has focused on the three interrelated themes of Climate Change and Water Security (Theme 1), Sediment Sources and Dynamics (Theme 2), and Tools for Integration in Watershed Management and Governance (Theme 3). To depict the interactions and value of three complementary and intertwined research themes, informed and influenced by other forms of knowledge, we have found it helpful to conceptualize the process using the analogy of a braided river, depicted in Fig 3.

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Fig 3. Schematic diagram depicting integrated watershed research in the Nechako as analogous to a braided river.

https://doi.org/10.1371/journal.pwat.0000263.g003

By envisioning our collective research as a braided river (Fig 3), we can reflect on the “work of a river”, which is to move water and sediment downstream. This shapes landscapes, generates new deposits, and eventually delivers to the ocean. In Fig 3 the upriver reach comprises three independent streams of research, shown moving separately. As material settles and forms deposits, or products of our research effort, the streams start to mix, sharing content and branching out. The process of river braiding is dynamic, with continuous interactions between water and sediment such that the “work” has far-reaching downstream influence. Contributions from tributaries, similar to influences from other forms of knowledge, add to the flow of information and ideas.

Interactions and combinations depicted in Fig 3 also emphasise the ‘emergent’ nature of our overall research design: recognising the value of being able to distinguish specific themes and disciplinary threads as separate contributions, while also recognising the benefits, synergies and sense of ‘confluence’ as the different research themes influence each other. Core features of each research theme are now introduced, each reflecting the entrance points on the left-hand side of Fig 3.

Research themes: Methods, findings and key insights

In keeping with the separate but interconnected approach, it is informative to introduce the IWRG’s work in relation to specific themes prior to profiling examples of connections and confluence across themes. Table 1 provides an overview of the different research themes, their overall scholarly orientation, scales of analysis, goals, and methods.

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Table 1. Characteristics of watershed research across three themes: Disciplines, unit of analysis, goals, approach and methods.

https://doi.org/10.1371/journal.pwat.0000263.t001

Table 1 underscores differences and complementarity across themes. While Themes 1 and 2 have primarily focused on the scholarship of discovery, Theme 3 has prioritised the scholarship of integration, providing a key feature of our integrated watershed research. The following sub-sections provide selected details on the methods and approaches used by each theme along with some key findings from the past decade of research in the Nechako Watershed.

Climate change and water security

To address Theme 1 objectives on climate change and water security in the Nechako Watershed, several datasets and methods were used. This included application of in situ data, reanalysis products and numerical models to infer climatic trends and their hydrological impacts. For instance, to characterize the Nechako’s changing hydroclimate, we applied ANUSPLIN, a spatially-distributed and observation-based dataset of daily minimum and maximum air temperature and total precipitation at a horizontal resolution of ~10 km [66]. Trends were assessed at both the grid scale and for spatially-aggregated values for the entire Nechako Watershed and its principal sub-watersheds over 1950–2010. Furthermore, observed daily streamflow data from the Water Survey of Canada (WSC) were used to assess trends over the same period for the Nechako River mainstem and its principal tributaries.

Numerical models offer the opportunity to reconstruct variables like water temperature and streamflow in data sparse regions such as the Nechako Watershed. The Air2Stream model [67] forced by ANUSPLIN daily air temperature and WSC daily streamflow records were used to simulate historical trends in river water temperatures for six sites in the Nechako Watershed [68]. As well, the Variable Infiltration Capacity (VIC) model [69] was applied to the entire Nechako Watershed to obtain gap-free time series of grid-scale runoff and routed streamflow for key sub-watersheds (e.g., the Stellako, Nautley and Stuart rivers) and the mainstem Nechako River (in naturalized conditions) up to its confluence with the Fraser River. The VIC model was run for both historical (1950–2021) and future (2022–2100) periods forced by a reanalysis product and climate model projections, respectively, at a 5 km spatial scale.

Statistical analyses revealed an average 2.3°C increase in air temperatures across the Nechako Watershed for 1950–2010 [8]. Concurrently, total annual precipitation across the Nechako declined marginally by 5%; however, a 10.5% decrease in snowfall was compensated by significant increases in rainfall at Fraser Lake and Fort St. James [20]. In response to both climate change and water management, flows declined by 40% over 1950–2010 for the Nechako River mainstem as gauged at Isle Pierre. Unregulated rivers such as the Stellako, Nautley and Stuart also experienced declines of 27%, 29% and 2%, respectively, over that period. Air2Stream model simulations then revealed a general 0.7°C warming trend in summer water temperatures at six Nechako Watershed sites from 1950 to 2015 [68]. To further our understanding of spatio-temporal variations in water temperatures and to better constrain modelling efforts, 31 sites across the Nechako Watershed were instrumented with stream temperature loggers starting in 2019 [70].

VIC model simulations for 1950–2021 revealed substantial decreases in flows due to the inter-basin diversion of water from the upper Nechako. Future projections of climate conditions from 17 climate models and two climate change scenarios suggest a potential shift from a snowmelt-dominated to rainfall-dominated hydrological regime for the Nechako Watershed by 2100. In sum, a significant warming trend from 1950 to present was observed across the Nechako Watershed, altering regional hydrology and stream temperatures including the timing and volumes of spring freshets and peak summer water temperatures; these trends will likely amplify under future climate warming in the 21st century.

Sediment sources and dynamics

One of the main concerns of the local communities and government agencies in the Nechako Watershed is how fine-grained sediment (i.e., silts and clays) are influencing the aquatic habitat of salmonids and the endangered Nechako white sturgeon (Acipenser transmontanus) [71]. Fine-grained sediment can be detrimental to aquatic organisms for several reasons, including: (i) physically covering eggs on spawning areas and thereby reducing the flow of oxygen through river gravels; (ii) by infilling of interstitial spaces of gravels thus preventing eggs from adhering to suitable sized substrate; (iii) by interfering with exposed soft tissues and membranes (e.g., gill function); and (iv) by negatively affecting the consumption of invertebrate prey by drift-foraging salmonids when fine sediment concentrations in the water column are high (i.e., reduced visibility) [72, 73]. In addition, fine-grained sediment can carry chemicals, such as metals, microplastics and persistent organic pollutants, that are toxic to organisms. Theme 2 addressed this concern by determining the source of the sediment and by assessing its quality.

The sediment source fingerprinting technique is a way to identify the main sources of sediment being transported in a river by matching the physical, biological and geochemical properties of sediment to its potential source material [73]. Therefore, samples of fine-grained sediment have been collected from the Nechako River mainstem and several key tributaries since 2015. In addition, a sediment core was collected in 2014 from the floodplain of the Nechako River near Vanderhoof to reconstruct changes in sediment sources over the last ca. 70 years. Soil samples were collected from a variety of land uses (e.g., forested and harvested land, agricultural land) and from eroding channel banks. In 2018 there was a severe wildfire in the watershed, so soil samples were also collected soon after the fire, to be included in the sediment fingerprinting. Statistical tests and a numerical unmixing model were used to compare the properties of the sediment to those of source materials and quantitatively determine the main sediment sources. The sediment samples were also analysed for metals and organic contaminants like polycyclic aromatic hydrocarbons (PAHs).

Based on the sediment samples collected in 2015, most of the sediment in the Nechako River mainstem during the sampling season was from the erosion of channel banks [74]. Topsoil from forested and agricultural lands were also identified as important for certain parts of the watershed, especially in the area near Vanderhoof. Reconstruction of changes over time, using the sediment core, showed that variations in sediment sources and the characteristics of the sediment (e.g., particle size composition) were linked to the construction of the Kenney Dam (operational in 1954) and the impacts of deforestation by the forestry and agricultural industries. Superimposed on these have been wildfires and a major mountain pine beetle infestation leading to higher erosion rates in the affected areas.

Chemical assessment of sediment in the area upstream of Vanderhoof was elevated in persistent organic pollutants and metals like zinc (Zn) [75]. More recent work assessing the effects of the large Shovel Lake wildfire in 2018, showed that it enhanced erosion and caused sediment to be delivered to tributary streams in areas that were burnt, although the wildfire signal became diluted in the Nechako River mainstem due to additional inputs from channel banks, etc. [24]. The wildfire also caused topsoil and tributary sediments to be contaminated with PAHs [25]. Thus, the Theme 2 work demonstrated that erosion of channel banks, topsoil from forested and agricultural land, and erosion following wildfires delivered sediment and associated contaminants to key habitats for aquatic organisms such as salmon and sturgeon.

Tools for integration in watershed management and governance

The third theme in the IWRG portfolio is oriented to the scholarship of integration and application, with a focus on tools and processes to support integrative approaches to watershed governance and decision-making, with implications for both social and environmental determinants of health [13, 51]. This work is informed by past and ongoing health-oriented research in other river catchments and watersheds—most notably in the Oceania region and across Canada (see for example: [13, 14, 76–81]). The orientation of Theme 3 was also informed by related research collaborations within the Nechako, including active engagement with a range of partner organisations within the watershed (see [7, 51]). In combination, these precedents underscored the particular need for attention to integrative decision-support systems that are better equipped to respond to combined environment, community and health concerns. Informed by this background, a guiding question informing Theme 3 was: How can integrative tools and processes be optimized to increase understanding of the cumulative impacts of environment, community and health changes within the Nechako Watershed, and inform and support intersectoral action and watershed governance?

The primary focus for Theme 3 was the identification, refinement and testing of a series of tools and processes, with particular emphasis on the development, collaborative refinement and evaluation of a geospatial web-based archiving and sharing tool, now known as the Nechako Watershed Portal [82]. The portal was initially designed with First Nations communities for ongoing use, development and refinement by key users such as Tŝilhqot’in National Government and Takla Nation [83, 84]. The choice to orient Theme 3 research toward this integrative portal tool was informed by principles of integrated knowledge translation, and knowledge-to-action research [85, 86]. As a key ‘tool for integration’, the development and refinement of the portal tool was undertaken in conjunction with several potential portal user groups. In addition to the IWRG research team itself, other user groups include the Nechako Environment and Water Stewardship Society, Cheslatta Carrier Nation, and Nechako Lakes School District 91 alongside an expanding collaboration with the Nechako Watershed Roundtable, which was formally established in 2015 [87].

To achieve this, Theme 3 developed a portal learning community (approved by UNBC Research Ethics Board File No. E2015.0204.010.00) to support an iterative process of collaboration, knowledge synthesis and exchange with portal user groups. Through a combination of workshops, portal development and training processes, as well as graduate student research projects, the portal user groups played an instrumental role in guiding portal refinements and identifying priorities for future research and development (see for example, [58, 88]). Importantly, Theme 3 focused on developing as well as refining this integrative tool through collaborative and cross-disciplinary processes. This approach fostered connections across IWRG research themes (Fig 3), while also expanding opportunities for knowledge exchange and decision making among a range of watershed partners, including a series of portal workshops at Nechako Watershed Roundtable events.

A key feature in the development of tools for integration in the Nechako, is the interaction with related collaborations exploring integrative tools and processes in other watersheds and related contexts. Of particular note is cross-fertilisation with a five-year UNBC-led project, launched in 2017 (co-led by Parkes) titled the “Environment, Community, Health Observatory (ECHO) Network”. The ECHO Network created opportunities to connect collaborative efforts within the Nechako, to national and international research partners [89, 90]. The collaborations, developments, and refinements of the portal provided the opportunity for what was initially an ‘IWRG Portal’ to be expanded and combined with other emerging portal initiatives. This expansion led to the creation of the ‘Nechako Watershed Portal’, supported by a series of videos and guides developed and profiled on the ECHO Network YouTube channel and other information pages [91–95]. Key integrative functions of the Nechako Watershed Portal are expanded in the next section, profiling how Theme 3 development of this tool is now being utilised as a shared geospatial archive by the IWRG team, as well as community partners. Ongoing activities are creating new opportunities for cross-referencing and sharing information across groups as well as fueling interest in harnessing these integrative tools to amplify co-benefits across environment, community and health interests in the Nechako.

Connecting hydrometeorology and river geomorphology

One example that illustrates the benefits of a multidisciplinary approach for understanding the behaviour of the Nechako Watershed, is the collaborative work on water flows (Theme 1) and sediment dynamics (Theme 2). Movement of surface water is often the driver of landscape erosion and the transport of sediment and associated chemicals. Thus, the hydrological work described earlier was crucial in the interpretation of the sediment source work. For example, the reconstructed sediment sources and dynamics determined using the floodplain core collected at Vanderhoof, as illustrated in Fig 4, relied on river discharge data for the same time period. The temporal pattern of discharge is similar to that for the main sediment sources, and therefore, is fundamental in explaining river channel processes. Utilizing the joint discharge and sediment sources data provides evidence that construction of the Kenney Dam and Nechako Reservoir in the 1950’s, and subsequent flow regulation, are likely a major factor in explaining sediment fluxes through the erosion of channel banks.

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Fig 4. Chronology and changes in sediment sources with depth in a sediment core collected in 2014 along the banks of the Nechako River in Vanderhoof.

Left: relative source contributions (green: forested land, blue: channel bank, brown: agricultural land). Right: annually averaged streamflow based on estimated year for the Nechako River at Vanderhoof (modified from [74]). Source data to create Fig 4 are available in S1 Table.

https://doi.org/10.1371/journal.pwat.0000263.g004

Given the projected changes in air temperature and precipitation determined for the Nechako Watershed as part of Theme 1 (described above), it is expected that these will have profound effects on future sediment and chemical dynamics. Thus, the modelling work being undertaken under Theme 1 guides the direction of future research in the watershed. This future work is also being informed by concerns from community groups and government agencies. An example of this is the recent incidence of large and severe wildfires in the watershed since 2017. Climate projections suggest that these large wildfires will continue into the future and are likely to become more frequent given increases in air temperature, changes in precipitation regimes and concomitant effects on vegetation cover. Given the knowledge gained by work on the Shovel Lake wildfire in 2018, ongoing work is assessing how the future wildfire regime in the watershed will impact surface runoff on hillslopes, soil erosion, and the transport of sediment and associated contaminants like PAHs. In turn, such knowledge will inform mitigation options to limit the detrimental hydrological and geomorphological effects of severe wildfires on aquatic ecosystems.

Integrating existing knowledge and fostering knowledge exchange through the Nechako watershed portal

The multidisciplinary connections between the discovery-oriented research of Themes 1 and 2 (Fig 4), raise questions of what other points of connections and different kinds of knowledge can be depicted across themes. In keeping with the ‘scholarship of integration’ emphasis on advancing what we know by connecting across disciplines [48], one approach our IWRG team has found helpful is to add new layers to a growing suite of time-series profiling different aspects of understanding of the Nechako over time (Fig 5).

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Fig 5. A composite time-series for the Nechako watershed case study, showing mean annual air temperature (for the area encompassing Vanderhoof), daily streamflow for the Nechako River at Vanderhoof, proportion of fine sediment derived from eroding channel banks, Chinook salmon escapements and annual number of publications, 1950–2023.

Source data to create Fig 5 are available in S1 Table.

https://doi.org/10.1371/journal.pwat.0000263.g005

As part of the suites of ‘tools of integration’ explored in Theme 3, a cross-theme commitment, led by the Theme 3 research team, has been to iteratively develop and refine a four-step protocol to develop a ‘saturation search’ of all journal articles that have been published within the Nechako Watershed, to make this available to UNBC researchers, watershed partners and the wider public. As far as our IWRG research team is aware, this four-step, locationally specific approach to identifying and sharing publications within a watershed (described below) is a unique contribution that has not been trialed in other watersheds and contexts. These efforts to surface, share and integrate existing knowledge into our research processes add another layer to the scholarship of integration for the IWRG Nechako case study, depicted by the inclusion of the publication time-series to the expanding ‘composite time-series’ for the Nechako (Fig 5).

Creating a time-series of all published papers in the Nechako is the first step in the four-step ‘saturation search’ protocol. This begins with an English-language Web-of-Science search for all journal articles with titles or abstracts that can be identified using any BC government-identified locations available on DataBC [96] within the boundaries of the Nechako Watershed. This search is combined with a snow-ball method based on papers known to IWRG researchers which, in combination, includes some sources outside of journal articles. Duplicates are identified and removed using DistillerSR software. Literature from the snow-ball sample that is not (also) identified by the locational terms are used to iteratively refine and expand the list of search terms. The current running total of papers published in the Nechako Watershed since 1934 is 766 papers.

The second step of the saturation search protocol is to import key metadata (title, author, year, publication details, abstract) into a publicly available Zotero library. This Zotero library [97] enables anyone, including IWRG team members and all those with access to the internet, to search for papers that have been published in the Nechako Watershed. The intention is for this library to be updated annually and, using an iteratively refined search strategy to expand the search to include systematic approaches to identifying other kinds of literature and resources (publicly available reports, videos, theses, etc.).

A third step is a high-level categorisation of the literature identified by the saturation search using key characteristics (thematic orientation, methods, populations) and trialing ways to map and profile this using visual tools such as a Sankey diagram. A sample of this approach, depicting the primary theme for all literature identified 1934–2023 is presented Fig 6.

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Fig 6. Temporal and thematic distribution of papers published within the Nechako watershed, 1934–2023, based on BC government-identified locations within the watershed boundary and snow-ball selection, categorised by year of publication, and primary thematic code (environment, community, health).

Figure courtesy of Jonathan Doyon and Margot Parkes.

https://doi.org/10.1371/journal.pwat.0000263.g006

The fourth step in sharing and profiling this saturation search and supporting integration of and access to existing knowledge, is to provide a geospatial attribute for all literature identified, and to import all journal article metadata (not the articles themselves) as spatially referenced submissions in the Nechako Watershed Portal [82]. This enables anyone with access to the portal, to find resources from the saturation search either through spatial or text search. The team anticipates this geocoding step to be completed within the portal before the end of 2024.

Finally, in an overt effort to deepen the potential scope for teaching, learning, application and knowledge exchange, Theme 3 team members are working with Theme 1 and 2 team members to develop and curate ‘integrative learning projects’ for the Nechako Watershed. Each project curates selected resources (drawing, for example, from data, information and resources across all three IWRG Themes, and the saturation search) and can be password protected as needed. A pilot ‘integrative learning project’ profiling research, findings and connections across all three IWRG themes, can be accessed via the Nechako Watershed Portal (https://nechakowatershed-portal.ca/) which provides a map-based, publicly accessible form of supplementary material, supported by a guide for accessing, exploring and interacting with this project [98]. As detailed in this project guide, any user arriving at the Nechako Watershed Portal landing page can anonymously view and interact with this project, but do not have access to edit or change information [98]. Interested users can also request a password to access other information made available within the Nechako Watershed portal by IWRG and other partners.

Currently these ‘integrative learning modules’ are being piloted with a variety of partner groups in the Nechako, including School District 91 and the Nechako Watershed Roundtable. An ongoing collaboration with Cheslatta Carrier Nation and their archivist has resulted in a Collaborative Research Agreement for continued work with Theme 3 team members to develop a similar approach for profiling and sharing the public domain features of this First Nation’s archive on the Nechako Watershed Portal.

These efforts to integrate, archive and share existing knowledge—supported by the Nechako Watershed Portal—contribute to the wider intention of our IWRG case study, to profile and integrate a diverse understanding of existing knowledge in the Nechako Watershed and to take a further step towards answering the challenging question of ‘how do we know what we know’ about the Nechako across academic disciplines. As we discuss in the next section, these efforts are also intended to inform new phases of work that strengthen understanding of the interconnected issues of climate change, watershed security, health and well-being, in the Nechako and beyond.

Hydrometeorological and geomorphological events

Although not surprising, a core insight from IWRG’s work is the imperative of the global climate crisis as a key driver of change across the entire Nechako Watershed, and the far-reaching implications for water security in the region. A direct consequence of climate warming is the enhanced potential for extreme hydrometeorological events including heavy precipitation and floods (e.g., [99, 100]) as well as heat waves and droughts (e.g., [101, 102]). This became particularly evident during 2021 as an early summer heat wave brought unprecedented temperatures to BC including the Nechako Watershed [103, 104]. Another extreme event affected BC in mid-November 2021 when a pair of land-falling atmospheric rivers caused catastrophic flooding in the lower Fraser River Valley [105]. Although this did not directly affect the Nechako Watershed on this occasion, it demonstrated the vulnerability of large watersheds that have headwaters close to the Pacific Ocean. Indeed, atmospheric rivers have become a growing concern for watersheds in western North America (e.g., [106–108]. Since 2022, the Nechako Watershed has experienced continued extreme conditions, with well above average air temperatures (including the warmest year on record in 2023; see Fig 5) and a persistent drought, resulting in multiple, massive wildfires and poor air quality in spring and summer 2023 [26, 109].

Tracking the emergence of these extreme hydrometeorological events and their impacts demands immediate attention. In particular, the network of stream temperature loggers deployed across the Nechako Watershed allowed an evaluation of how water temperatures responded to the early summer heat dome in 2021. While headwater creeks in the Coast Mountains remained cool (<5°C) due to rapid alpine snowmelt, some low elevation creeks attained maximum water temperatures near 30°C by the end of June 2021 [110]. Implications of such warm water temperatures on aquatic habitat and various fish species thus require careful consideration. This is particularly important in the regulated Nechako River where keystone species such as Chinook salmon (Oncorhynchus tshawytscha), sockeye salmon (Oncorhynchus nerka) and the endangered Nechako white sturgeon (Acipenser transmontanus) are susceptible to hydrological and water temperature extremes.

Another emerging imperative is the impact of atmospheric rivers on water resources and sediment transport in the upper Nechako Watershed [108]. Atmospheric rivers contribute up to one third of the annual precipitation in coastal BC watersheds [106–108]. While atmospheric rivers generally bring beneficial precipitation and replenishment of terrestrial water resources in low-impact storms to the Nechako Watershed, they can on occasion accompany extreme precipitation and flooding as evidenced across the lower Fraser Valley in autumn 2021. Heavy rainfall with land-falling atmospheric rivers often induces pulses of water, erosion and sediment transport from headwater creeks, particularly during fall when salmon migrations occur. Ongoing research on the atmospheric river phenomenon and its implications to the Nechako Watershed therefore remains a top priority of the IWRG as these storms are anticipated to intensify and become more prevalent across coastal BC in the 21^st century [111].

Cumulative natural and anthropogenic landscape disturbances

Coupled with these hydrological and geomorphological changes due to the climate crisis are ongoing changes in vegetation cover and land management. Warmer temperatures and changes in precipitation regimes are altering vegetation cover. The agricultural area near Vanderhoof, for example, is growing in response to more favourable climatic conditions [42]. This expansion is often at the expense of the natural forest cover, which has also been heavily impacted by a major mountain pine beetle outbreak. This outbreak, that mainly occurred from the late 1990s to 2015, was due to a reduction in very cold air temperatures during winter (i.e., below –40°C) that normally kept the mountain pine beetle under control [44, 46]. The increased number of dead trees created a source of fuel, which, along with rising summer temperatures, is partly responsible for the increase in large wildfires in recent years. As described earlier, the recent increase in severe wildfires is having a profound effect on the hydrology and geomorphology of the watershed, which in turn will have implications for water resources, and terrestrial and aquatic habitats.

Layered on these changes are further, emerging developments in resource extraction, several of which have arisen since the IWRG formed, and adding to known challenges of cumulative impacts [8, 45]. For example, the large, 670-km long Coastal GasLink natural gas pipeline links the north-east of BC to the BC coast and runs through part of the Nechako Watershed. In addition to disturbing landscapes, the pipeline crosses numerous streams, rivers and wetlands and during its construction and ongoing maintenance has been responsible for erosion of the landscape and the delivery of sediment and contaminants into important aquatic habitats [112].

These cascading and complex interactions between climate change and watershed management [7, 34] have created a new sense of urgency for those that reside in the watershed. This has necessitated new interactions and conversations amongst the IWRG researchers, partners, community groups and First Nations, which has also provided new challenges and opportunities for research in the area, of which some will be addressed in future phases of work. As we look ahead to new phases of research, we have become increasingly aware that the evolving and changing nature of issues in the Nechako Watershed are best addressed with a transdisciplinary approach to knowledge generation and exchange that are nimble and responsive enough to be able to react quickly to pressing needs as they arise. Our watershed-level findings also reinforce findings across provincial, Canadian, and international contexts that academic research is only one of numerous knowledge systems that need to be respectfully engaged with so as to understand and respond to the deepening complexity of cumulative impacts [89, 113, 114].

Strengths and innovations: Integrative lessons and the braiding of research themes

In designing an integrative program of research that addresses the thematic scope of the IWRG, our case study has involved teamwork across disciplines with a mix of multidisciplinary and interdisciplinary features with intentional efforts toward the ‘scholarship of integration’ [48, 63]. The ‘multidisciplinary’ features acknowledge the ways in which IWRG researchers in each theme address research questions in a manner relevant to their respective disciplines, and yet also seek to combine and link their research with other themes. Emphasis on integration is driven by shared interest in water security issues in the same watershed, and also by the interest in cross-fertilisation between different understandings, demonstrating characteristics of ‘interdisciplinary’ research [5, 115]. Development of the IWRG has also been informed by questions and interaction with our community partners, and thus appreciation of and interaction with knowledges outside the academy, creating opportunities for our IWRG case study to also develop some features of a ‘transdisciplinary’ approach [116–118]. Throughout our case study, the impetus for our IWRG team to develop more overtly transdisciplinary connections across all three themes has deepened, informed by knowledges and applied challenges that extend beyond the academy, and which position IWRG as part of a wider system of knowledge within the Nechako Watershed, learning alongside, and informed by Indigenous, local community, government knowledges and, increasingly, next-generation voices, spanning youth and emerging researchers [60–62, 119, 120].

The insights from our case study have also been linked by an expanding appreciation of the strengths and weaknesses of the ‘braiding’ work we have been doing to date, and the relevance of these lessons for advancing both understanding and collaboration to address water security. Just as multiple knowledges have informed the development of IWRG work, the team has also become aware of other ways in which braided river metaphors are being used in other contexts such as their relevance to inform interactions and learning between Indigenous and non-Indigenous knowledges in geomorphological research [121], and as a metaphor for STEM career development [122]. Insights from other approaches to the ‘braiding of knowledge’ is especially relevant to inform and push intentions and reflections on how to engage with Indigenous knowledge and leadership in the Nechako through, for example, the Yinka Dene Water Policy and laws [29], as well as how best to engage with and serve youth and K-12 interests through partnerships with School District 91 and beyond [60, 61, 120]. These insights also encourage consideration of how best to design future research in ways that foster reciprocity and knowledge exchange with First Nations and other local knowledge holders, ranging from important practical considerations such as placement of equipment, to what field sites it is possible or appropriate to access, through who and how to approach during the planning and design of research, and subsequent processes of outreach and knowledge exchange.

Gaps and priorities for future research

Our IWRG case study in the Nechako has underscored the ways that an integrative approach remains essential to address the complex interactions among climate change, land use, watershed dynamics and ecological processes, all of which have far-reaching implications for the communities living within the watershed. Thus, in our ongoing work, a central theme is the climate crisis as a cross-cutting driver of watershed change. With the addition of a new team member and a fourth theme focused on fish ecology, as well as collaborations with several new early career researchers at UNBC with expertise covering all ongoing research themes, the IWRG is undertaking a new phase of work with an integrative response to climate change, watershed security and community connections in the Nechako Watershed [123]. This effort includes the establishment of experimental watersheds to better understand processes at the sub-watershed scale and their impacts on fish. For instance, as described above, we are exploring how atmospheric rivers affect runoff, erosion and sediment transport in upper Nechako waterways during fall salmon migrations.

There are mounting concerns on the current state and future fate of fish in the Nechako River. As a managed waterway also susceptible to climate change, the Nechako’s water quality and quantity are changing. New effort is therefore focusing on tracking thermal refugia along the mainstem Nechako River. An expansion of stream temperature monitoring and an exploration of groundwater inputs to the system is providing information on where migrating salmon may seek refuge during heat waves and low flow periods. Another ongoing knowledge gap is the availability of groundwater resources, particularly in the Vanderhoof agricultural belt where diminishing surface waters may intensify the depletion of aquifers for irrigation and domestic water use.

Building on its past efforts, it is important for the IWRG to find ways to deepen meaningful connections and engagements with the First Nations across the Nechako Watershed in the coming years [51]. As part of an expanded, transdisciplinary approach, engaging with and learning from Indigenous knowledge, and across generations, will be essential features of future community-based research within the unceded territories of First Nations throughout the watershed [51, 61, 119]. One new initiative that may inform future IWRG efforts, is focused on exploring the co-benefits of water, land, health and climate connections in northern BC, including the Nechako. Funding from the BC Ministry of Health and Northern Health seeks to amplify lessons from intergenerational, intersectoral and Indigenous-led approaches to land, water, climate and health issues in rural, remote and Indigenous communities. This work is informed by meetings focused on ‘Coming together as a whole in the Cowichan Watershed’ [124], and a related gathering co-designed and co-hosted with Stellat’en First Nation, titled “Tsuyawh Ltsunizdoodilh (Everybody/ Everything pulling together). Lands, Waters, Climate & Health connections in the Nechako watershed” [120].

Looking ahead, the hope is that engagement, monitoring, and knowledge exchange across all communities in the Nechako (including First Nations) will be enabled through the further advancements with the Nechako Watershed Portal, including ongoing expansion of this made-in-the-Nechako archive of existing resources and the ongoing spatial referencing of the ‘saturation search’ of resources published in the Nechako [97]. A notable advance being led from Takla Nation’s own use of a different iteration of the portal [83], is to increase options to import community monitoring data into the portal using phone-based applications; as well as new and expanding functions to enable users to collate, curate and display this information to serve their own needs through the recently developed ‘project’ function [98].

While the Nechako Watershed has unique characteristics, like any watershed, it also shares similarities with other watersheds across Canada and beyond. Heavily regulated watersheds of ecological importance and of similar catchment areas in Canada are the Kootenay, Manicouagan, and Saint John (Wolastoq) rivers [18]. The regulated Klamath River (USA), Weser River (Germany), and Olifants River (South Africa) approach the catchment area of the Nechako providing further opportunities for cross-comparisons globally [125]. Thus, knowledge gained through our research in the Nechako Watershed can offer insights on water security, and the cumulative impacts of climate change, water management, and land use and landcover changes to basins worldwide. Likewise, the IWRG can gain knowledge from comparator basins with extended literature searches.