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T’sihl Hlii Background

Tsihl Hlii Din (McCully Creek) is a 4th order stream which is located in the northwest region of British Columbia in the Kispiox valley. The McCully Creek watershed has an area of 169 square kilometres as shown in Figure 1. This watershed is also located within the boundaries of Wilps Xhliiyemlaxha’s traditional territory. Historically, McCully Creek has supported Chinook, chum, coho, and pink salmon, however, fish abundance has declined in recent decades with only pinks and cohos being observed in 2021, and 2022, respectively. It is uncertain whether or not Chinook and chum salmon are still present in this creek.

Figure 1. McCully Creek watershed. At the top of the map, you can see where the McCully Creek drains into the Kispiox River. The dashed lines are forest service roads in the Helen Lake area.

Two separate avulsion events in the lower reaches of McCully Creek may help to explain the fish declines being observed as these two events have drastically changed important salmon rearing habitats within McCully Creek. In the McCully Creek avulsion event in the 1990s, the McCully Creek changed its course from the wooded area, as seen in Figure 2 (orange line bottom right image), and cut through the pasture. This new reach washed away the pasture, and its soil, leaving behind a barren gravel bar. This new section of stream lacks in-stream complexity as there are very few riffles, pools, in-stream vegetation, large woody debris, and functional in-stream structures.

Figure 2. The top image illustrates where the new McCully Creek and floodplain are, and where the Kispiox River used to flow. The bottom image illustrates the level of disturbance the creek’s course change caused. A disturbed floodplain lies where the pasture land used to be. All fish habitat below the fan has been altered, or degraded, due to these changes.

In the second avulsion event, which was years later, the Kispiox River jumped its course to the opposite side of the cottonwood island in Figure 2. Before these two avulsion events, the McCully Creek used only one channel to drain into the Kispiox River. Now, because the McCully Creek occupies the old Kispiox River channel, the McCully Creek has to flow through two separate drainage outlets to the Kispiox River. McCully Creek’s total flow is therefore divided and this becomes evident in the summer when the water in these channels becomes very low. Because of these conditions, there are now intermittent salmon-rearing habitats and fish passage barrier risks in both of the drainage outlets. The left outlet, MC1 in Figure 3, is shorter at 500 meters in length, but it flows at an upslope to the Kispiox River when it contains water.

The right outlet, MC 2 in Figure 3, is longer at 1000 meters in length and flows downslope to the Kispiox River.  The consensus is that the downstream outlet, MC2, is the more suitable channel to contain McCully Creek’s flow. This is partly due to the fact that MC1 experiences excessive sediment buildup as it is a zone of high deposition caused by both the uphill slope to the Kispiox River and the Kispiox River flowing against the McCully Creek during the peak freshet. The instability being observed for these two outlets puts at risk the rearing salmon in these habitats. These unfavorable conditions have led to studies in the past, and more recently, a McCully Creek Working Group has brought together the governing Gitksan house group, adjacent landowners, regional scientists, and restoration specialists to work together and address these current challenges.

The Study Area

Figure 3. Water quality sampling sites within McCully Creek study area.

The study area in Figure 3 can be found in the lowest elevations of the McCully Creek watershed, where the McCully Creek drains into the Kispiox River. This is where GWA’s activities take place. The study area has seven sampling sites and they start 400 meters upstream of McCully Creek bridge, and end where the downstream drainage outlets meet the Kispiox River (MC1 and MC2 in Figure 3). The study area covers approximately 0.5 square kilometres. The Bio-geoclimatic zone (BEC zone) of the study area is classified into the Interior-Cedar-Hemlock-moist-cold variant 2 (ICHmc2) BEC zone and the study area has willows, cottonwoods, birch, spruce, alder, red osier, and a variety of grasses and herbaceous species along its streambanks. Since the avulsion events in the 1990s, the beavers have been more active in this area, especially in the drainage outlets. The beavers now occasionally dam the downstream reach of MC2, making this reach suitable for salmon rearing in the spring and summer seasons. The reasons for this are that the pooled water behind the dam prevents the channel from drying, and the deeper water remains cooler in the warm months.

GWA Activities

Bank Stabilization and Gravel Bar Reclamation

Figure 4. Top left & right images illustrate willow berm construction on the left bank near the fan area. The bottom left image illustrates the 150 meters of bank stabilization structures being built on river left of the fan area. The bottom right image shows the effectiveness of bank stabilization structures placed at a vulnerable cut bank near MC7 of the study area.

GWA has been actively involved in bank stabilization efforts and gravel bar reclamation as shown in Figure 4. GWA, in collaboration with the McCully Creek Working Group, has stabilized approximately 150 meters of stream bank on the river-left banks of McCully Creek in the fan area. This stabilization was achieved through the use of heavy machinery, large cottonwood trees, and local shrubs. The purpose of the bank stabilization structures is to prevent anastomosing of the main channel. Anastomosing channels in the fan would lead to insufficient water volumes in MC1, or MC2 in the warm season. With these stabilization structures in place, the channel was able to ‘choose’ its preferred flow path; as of 2022, this path is down the MC2 reach. This is a good, new development within the study area as this outlet now has the potential to maintain sufficient flow in the channel the Kispiox River once occupied.

A bank stabilization structure has also been constructed below MC4 in the study area (see Figure 3) to protect the adjacent land owner’s property from further land loss. This structure can be seen in the background of Figure 4 (bottom left image) on the banks below the grassland.

The willow berms constructed in Figure 4 serve to stabilize the banks through their root systems, but they also serve to ‘green up’ the barren gravel bars. This ‘greening up’ of the gravel bars is another important activity which GWA is currently working towards. In the long-term, the gravel bars will flourish with trees and shrubs. This activity will eventually bring plant and animal diversity back to this area.

Water Quality and Quantity Program

Figure 5. Top image illustrates water quality sampling near the fan area at McCully Creek. The bottom image illustrates a velocity and discharge measurement in the MC2 outlet channel.

GWA runs a Water Quality and Quantity program for the study area at McCully Creek. The program was initiated in 2021 and was developed with the help of the Skeena Fisheries commission (SFC). The Water Quality and Quantity program involves water sampling from each of the seven sites in Figure 4, where the objective is to obtain water column data from the rising, peaking, and falling limbs of the spring freshet hydrograph. A side objective of the program is to collect and measure water samples after a storm event to assess how stream characteristics respond. In the Water Quality and Quantity program turbidity, total suspended solids, electrical conductivity, water temperature, and water level data is gathered from May until the end of October; with dissolved oxygen and pH being added to the program in 2023. There will also be a lab analysis component in the program this year as particle size distribution and chemical analysis of the water column will be assessed for McCully Creek. The overall objective of the Water Quality and Quantity program is to ensure that i) There are no water quality ‘stressors’ which may be affecting the rearing salmon populations, and ii) The bank stabilization structures are working to prevent erosion of sediments into McCully Creek. For instance, with the turbidity data we can assess the levels of turbidity in sites upstream of the bank stabilization structures and compare those data with levels below the bank stabilization structures. Preliminary results suggest that the levels of turbidity, and therefore, amounts of suspended particles in the stream, are similar above, and below the bank stabilization structures. This is a desired result. If the bank stabilization structures were not preventing erosion, we would expect to see higher turbidity levels below the bank stabilization compared to the sampling site above the uppermost bank stabilization structure. GWA will perform the correct statistical tests to confirm if there is a statistically significant difference between sites that are above, and below bank stabilization structures.

Fish Salvage

In 2023, GWA will perform fish salvaging in the lower reaches of McCully Creek to ensure fish populations do not perish in the low water conditions. The fish will be salvaged and transported to stream channels which have adequate water throughout the warm months.

Communications and Outreach

GWA routinely provides updates to the working group and the Gitksan governing house group- Xhliiyemlaxha. GWA works closely with all collaborators to ensure the activities we carry out are in the best interest of the McCully watershed.

In 2023, GWA will also hold a field day at McCully Creek to engage the youth in what it means to act as stewards of the land. Information will be shared as to why this land/study area needs restoration, and what the benefits will be in the long term. The activities being planned will give the youth the option to be active members in the restoration plans. The youth will have a chance to plant their choice of local shrub, or conifer species in areas selected for riparian restoration. The youth will also have the chance to voice their opinion on other features they think the study area is lacking (large woody debris, root wads, etc.). The idea behind this engagement is to pique the youth’s interest in land stewardship through their own creativity. In this way, the youth will leave a long lasting, positive footprint on this land.

Future Plans

Fish Habitat Restoration

Fish habitat restoration has, and will continue to be, a priority in the lower McCully Creek watershed. To make the habitats more suitable for salmon rearing, the habitat needs to be suitable for invertebrates (salmon prey) as well. For habitats to be suitable for invertebrates, the study area needs pools, riffles, adequate water depth, large woody debris, functional woody debris, and in-stream vegetation. A lot of these features are lacking in this study area and so GWA hopes to add more of these attributes.

To improve the salmon rearing habitats is to encourage the salmon to grow bigger and stronger before they migrate to the ocean. If the salmon are bigger and stronger when they reach the ocean, they will have a better chance at survival. If more of the McCully Creek salmon survive out in the ocean, the better chance they have at making it back to their spawning grounds.

Large-scale Watershed Studies

GWA is also looking forward. Climate change is expected to have an impact on watersheds across the world. GWA is in the early stages of a large-scale watershed study for McCully Creek. The objective of this study would be to better understand how this watershed will be affected by climate change, and to mitigate the adverse impacts that are expected with climate change.


GWA would like to thank Xhliiyemlaxha for allowing GWA to work on their lands. We would also like to thank the adjacent land owners for their cooperation and help throughout this study. The members of the working group Skeena Fisheries Commission, BCFLNRO, Geomorphic, BC Cattlemen’s Association, the Department of Fisheries and Oceans Habitat Restoration Unit, and the adjacent landowners have also been very helpful throughout this study. Thank you to Gord Wilson at GWA for creating the maps used in this document. The Pacific Salmon Foundation has also generously provided funds which has made some of our activities possible.


BEC Zones in. the McCully Creek Watershed

Water Quality and Quantity Summary 2022

TSS Summary for McCully Creek 2022