Removing Aquatic Invasive Plants in Lillooet

Project Year: 2016-2017

View Provincial Database Record

Yellow Flag Iris: Monte Comeau CKISS

Project Lead

Lillooet Regional Invasive Species Society


Coastal Region


Project Type

Research & Information Acquisition

FWCP Contribution


Action Plan Alignment

Bridge-Seton Riparian Wetlands Action Plan

Project ID


LRISS Aquatic Invasives Project

Aquatic invasive species threaten riparian and wetland areas in the Bridge-Seton watersheds. In 2015, LRISS found invasives in several lakes, namely Yellow Flag Iris and Knotweed. Manual removal of Yellow Flag Iris is very labour-intensive, but eradication is an attainable goal. This project will remove Yellow Flag Iris and Knotweed in partnership with local stakeholders and First Nations.

This is a two-year project that will treat areas already found, inventory adjacent areas that are at risk of spread, and monitor the treatment for efficacy. The Aquatics Action Plan is currently being developed and these activities are a high priority for implementation. This project will result in: 60 kilometres of shoreline surveyed, 20 square metres of Yellow Flag Iris removed, and 6 square metres of knotweed removed. The removal and eradication of these invasives will allow for the regeneration of native riparian vegetation that will provide stream bank stability, cover, food and habitat for a host of species. Stream bank stability will prevent sedimentation of spawning areas for fish. Native plants and shrubs will provide breeding, cover and food sources for birds and wildlife. If the invasive sites are left, they will continue to expand and suppress native vegetation. Yellow Flag Iris is poisonous to humans and wildlife. Knotweed roots cause increased sedimentation because the roots do not hold soil as well as native plants.


Final Report: Executive Summary

The Lillooet Regional Invasive Species Society (LRISS) with the BC Hydro Fish and Wildlife Compensation Program grant has completed the second year of an Aquatic Invasives Project. The study area includes the Bridge-Seton Watersheds. Aquatic invasive species have been detected in the LRISS region and they have the potential to take over shorelines of lakes and creeks. Invasives, like Yellow Flag Iris, can create monocultures along riparian
areas that displace native plants and degrade fish and wildlife habitat.

The goals of this project included:

  1. Targeted inventory of Anderson Lake that could potentially be the source of Yellow Flag Iris that has
    established in Seton Lake.
  2. Targeted survey for Yellow Flag Iris on Tyaughton Creek.
  3. Remove the Yellow Flag Iris and Knotweed sites from Seton and Tyaughton Lakes including the channels of
    Portage Creek flowing into Seton Lake.
  4. Partner with local stakeholders and the Seton Lake First Nations (Tsal’alh) to educate and train them on
    how to identify aquatic invasives and remove them.
  5. Participate in local community events to education the general public about the impacts of invasives and
    how they can stop their spread.

Benefits to fish and wildlife include the following measurable goals for this project: survey 60 km of shoreline,
remove 20 square meters of Yellow Flag Iris, and remove 6 square meters of Knotweed.

Click the provincial database link below to read the full final report for this project.

View more about this project on the provincial database