It’s hard to ignore invasive aquatic plants when you live in the Okanagan Valley – it would be a rare person in our region who has never heard of Eurasian milfoil. However, the list of aquatic invaders is far more extensive than you could possibly imagine.

Like their terrestrial counterparts, aquatic invasive species (plants and animals) have been entering Canadian waters for centuries but never as rapidly as today. Fisheries and Oceans Canada states that aquatic invasive species have already been responsible for significant devastation of some native fish species and fisheries in Canada. Annually, the problem is responsible for billions of dollars in lost revenue and control measures. Consequently, there is a vast amount of attention being focused on aquatic invasives at all levels of government, and non-government organizations are also getting on the bandwagon.

At a provincial level, the Ministry of Environment has a staff person dedicated specifically to the topic of aquatic invasive species. Invasive species are threatening BC’s aquatic and riparian ecosystems, such as streams, lakes and wetlands, and the species that rely on them. Water-based recreation activities such as angling, boating and diving can spread aquatic invasive species to new locations. Plants, animals, and microscopic creatures can cling to clothing, equipment and boats. If not cleaned, these species can be introduced into new bodies of water.

Locally, there has not been a whole lot of attention on invasive aquatic species with the exception of Eurasian water milfoil (Myriophyllum spicatum). The Okanagan Basin Water Board (OBWB) takes the issue of milfoil quite seriously and has been responsible for its control in the Okanagan Basin since the 1970s. After many years of experimenting with different methods, the OBWB now focuses on harvesting in the summer and rototilling the root system on shallow portions of the lake floor in the fall and winter.

Invasive plants, such as milfoil and fragrant water-lily (Nymphaea odorata), and the invasive freshwater algae Didymo (Didymosphenia geminata), form thick mats on the surface of the water, which can impede light penetration to underwater plants and animals, hinder boat traffic, clog intake pipes of boats, foul fishing lines and nets and cause a danger to swimmers. Once established, these species are extremely difficult, if not impossible, to eradicate. Economically, the impacts of aquatic invasive plants can be devastating. Many of these species can cause increased boat repair and maintenance costs when they become tangled in motors. Real estate values can become depressed on waterbodies with aquatic plant infestations like milfoil. Water intake structures on dams can be damaged from mats of invasive plant materials. Management strategies to address infestations are extremely costly.

The intentional or accidental release of these species from garden ponds and aquariums into natural waterbodies is one of the primary pathways of introduction. Aquarium hobbyists, pond owners, pet store owners and customers, and water landscapers can prevent the establishment of invasive plants by making informed choices when selecting, trading, purchasing or disposing of aquatic plants.

Unfortunately, the concerns do not end with plants. In fact, aquatic invasive animals pose a far greater threat to our waterways. Of immediate concern are two freshwater mussel species, zebra and quagga mussels. These invertebrates rapidly colonize hard surfaces and can subsequently clog water-intake structures, impact recreation, alter food webs and affect water quality. Invasive mussels can affect entire ecosystems. Recent research has determined there is a high risk of invasive mussels not only surviving in some parts of Okanagan Lake, but there is a high potential for massive infestations.

When it comes to aquatic invasive species, the ecological balance of our lakes and rivers at risk, and so is our drinking water. Prevention of harmful new invasions is the first priority, as it is the most cost-effective way to deal with the problem. Once species are established, the task becomes far more complex and costly. The issue of invasive aquatics is a hot topic and it’s going to be the focus of a province-wide campaign in 2012. So watch for it, and in the meantime, take the time to become more familiar with aquatic invaders and learn what you can do to make a difference.

For further information on invasive plants contact the Invasive Plant Program Coordinator for the Okanagan-Similkameen, Lisa Scott at 250-404-0115 or email her at Or check out our website at


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