Eneas Creek Community Yellow-flag Iris Management
Since 2016, the Okanagan Similkameen Stewardship (OSS) has been working with local landowners along Eneas Creek and in the Garnet Valley to enhance and restore wildlife habitat along the creek. Between 2016 and 2019, we planted 2100 native trees and shrubs on the Okanagan Crush Pad property and have been doing invasive plant management since then.
In the summer of 2022, we focused on removal of Yellow Flag Iris from the creek.Yellow Flag Iris is a destructive invasive plant that chokes the creek and reduces habitat quality for wildlife while also increasing local flooding where it forms dense mats, blocking water flow. It spreads through
underground rhizomes as well as seed dispersal.
To remove the iris, expert Dr. Catherine Tarasoff recommends cutting back plants and installing a thick benthic barrier (PVC) for one year to suffocate the roots of the plants. Work such as this needs to be conducted with
appropriate Permits/Notifications and in the fisheries work window.
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In areas where there were single plants, removing the individual plant is recommended. It is important to dig out the entire rhizome/root as if part is missed, it will grow a new plant. Equally important is removing any seeds that you find. We kind of think they look like shishito peppers. These seeds will float downstream if left and grow new infestations of Yellow-flag Iris.
Four new stewards joined us through this initiative, and we completed iris removal on 5 Wildlife Habitat Stewards' properties, starting in upstream locations and working downstream in the direction that seeds are spread.
Many thanks to our project partners for their contributions:
Okanagan Basin Water Board
South Okanagan Conservation Fund
Habitat Conservation Trust Foundation
Environment and Climate Change Canada
BC Community Gaming Fund
A Case of Mistaken Identity
When not flowering, Yellow-flag Iris looks very similar to cattails and both grow in similar soils (wetland/riparian areas with slow moving water). So, how can we tell them apart?
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Cattails are arranged in rounded layers, rather than the flat fan shape typical of irises, including Yellow-Flag Iris.
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Yellow-flag iris have a very distinct ridge up the length of their leaves that is both visible and tactile.
Home to Endangered Species
About 85% of Okanagan wildlife species are dependent upon riparian habitats or use them regularly. Riparian areas are shorelines, strips of land beside streams, rivers, wetlands, lakes, and other water bodies. They support a community of moisture-loving plants that are distinctly different from aquatic vegetation, and from the plants growing in the drier grasslands and forests of the Okanagan and Similkameen valleys.
Many endangered and threatened species such as the Western Screech-Owl, Great-basin Spadefoot, Yellow-breasted Chat, and Great Basin Gophersnake depend on these areas for their survival.
Before and during...
What's next? Replanting with native species
Once the benthic barrier comes off, there will remain a rich, organic soil. Because this would erode if left barren, the covered areas will be replanted to the fast-growing Indigenous species typical of the area (eg. waterbirch, dogwood, and willow). While we will move the barrier to downstream infestations of Yellow-flag Iris, we will plant up the shorelines as we go as well.
