Written by: Angela Ten, Management Biologist
As part of TUC’s Reconnecting Canada campaign, we have been working to replace a set of hanging culverts on two tributaries to Waiparous Creek since 2019. We refer to these creeks as the Whispering Pines East and West tributaries, since they cross a road owned by the Whispering Pines Bible Camp.
These creeks are home to native Bull Trout (Salvelinus confluentus) and Westslope Cutthroat Trout (Oncorhynchus clarkii lewisii), which are both species at risk. In 2022, we successfully replaced one set of hanging culverts on the Whispering Pines West tributary, so this year, our goal was to replace the set on the East tributary!
Culverts are “hanging” when there is a gap between the bottom of the culvert and the top of the stream it flows into—kind of like a mini-waterfall. Just like a natural waterfall, hanging culverts can be a barrier for fish movement, as fish may be unable to jump high enough to close the gap between the stream and the culvert.
When this happens, populations on the upstream side of the culvert become isolated from the rest of the creek. Problems associated to this isolation are amplified when the upstream part of the creek is particularly small, like it is in Whispering Pines East.
Imagine that you and 100 other people living in a single apartment building. There is enough food and water for everyone and one room for each person. The doors to the apartment building only work one way; no one new can enter the building, and if you ever leave the building, you can’t come back in.
Things are fine at first—but then a fire destroys 10 of the rooms, and the rooms cannot be repaired. What do you do? Some people share their rooms, but they often get into fights over the lack of personal space. Others have no choice but to leave.
A decade passes, and you have kids in the apartment! There is enough room for the kids for now since they’re small, but space will be an issue once the kids grow up. The kids also need some space to play; the apartment has a small playground, but there are other families with kids, too, and not enough space for everyone. What do you do? Do you leave, or stay and fight for the limited space in the apartment and playground?
These are examples of some of the struggles that fish living in small, isolated populations face. A flood or drought that damages part of their habitat could lead to the death or displacement of a significant amount of fish. Sometimes, the remaining habitat is not suitable for all age classes of fish. Additionally, since no new fish can enter this population, the fish in the system can become more and more related to each other over time, causing issues with inbreeding (when relatives breed with each other) that can harm the population’s genetics.
At the Whispering Pines East tributary, the road was also causing a significant amount of sediment to be deposited into the stream when it rained. Since the valley here is so steep, the creek crossing was the lowest part of the road. As a result, whenever it rained, water would flow down the compacted road surface from both sides, picking up sediment as it went, before dumping this muddy water into the lowest part of the slope—the creek. This muddy water makes it hard for fish to see, and breathe and can bury their eggs, which are usually laid in loose gravels.
All this means that if we want to protect and conserve the native, at-risk trout that live in the Whispering Pines East tributary, we have to do something about these hanging culverts.
And in September 2023, we did! After several years of fundraising and hard work, we were finally able to begin the process of replacing the hanging culverts with an open-bottom arch. The process and results for the work at the east tributary is similar to that of the west tributary
Since the creek would have to be dewatered to minimize the impacts of construction on the creek, TUC staff installed nets to exclude fish from the dewatered area, performed several fish salvages within the dewatered area, and moved the captured fish to a safer spot in the creek. The creek was then pumped around the construction area.
To prevent the issues with the road from happening again, a significant amount of gravel was used to eliminate the dip in the road and lift it out of the valley. Moving and packing down all this material took a lot of time, so construction for this culvert took over 3 weeks to complete.
With construction complete, all that’s left is to restore the adjacent riparian area with some tree planting and woody debris distribution. This process was started in October 2023, and will likely continue for another year or two as we monitor the site. If you’re interested in getting involved with this project, and seeing this enormous arch for yourself, keep an eye out on our Eventbrite and social media pages for riparian planting volunteer opportunities in spring and fall 2024!
This project was financially supported by Alberta Environment and Protected Areas through the Native Trout Collaborative, the Alberta Conservation Association, the Calgary Foundation, the Bow River Basin Council, the Ghost Watershed Alliance Society, the Samuel Hanen Society for Resource Conservation, Environment and Climate Change Canada, TC Energy, and the Alberta Fish and Game Association. In-kind support was gratefully received from Alberta Transportation and Economic Corridors through gravel donations. Finally, TUC thanks the Whispering Pines Bible Camp for making the road available for construction, and for their continued support of work on this creek.