What looks like a simple pink aquatic flower has been causing complex issues in the irrigation canal between Calgary and Lake Chestermere.
Flowering rush was discovered along a 13-kilometre length of the canal in 2011, and Rocky View County’s (RVC) Weed Inspector Kendra Tippe said it’s an ongoing process to keep the invasive species under control.
“It’s quite a pretty flower and that’s why people might want to plant it in their ponds… but it’s actually a prohibited noxious weed under Provincial regulations that’s required to be destroyed,” said Tippe.
Tippe presented to the Agricultural Service Board on Feb. 20, giving an overview of what has taken place since the plant was identified and what actions are planned for this year to continue to remove the rush.
Native to Eurasia, the plant has a thick root system with triangular stems and pink and white petals, that if left unmonitored can crowd out other native species in the water system and contribute to a poor aquatic environment.
Because the plant can grow on the shoreline, partially submerged in water or completely submerged, Tippe said it can be difficult to spot the plant at first and to completely remove the plant once it’s been identified.
Tippe said the County has been working with Alberta Environment and the Western Irrigation District to manage the problem, which extends into the Chestermere Lake along the southern shore. In November 2011, 250 metres of the canal was dredged and the sides of the banks scraped to test whether that was a solution, said Tippe.
She said dredging continued in 2012 with a budget from the Alberta Environment Sustainable Resources of $300,000, but the funds could only cover a portion of the canal.
Tippe said flowering rush specimens were sent to Provincial weed specialists, and results showed the species found in the Chestermere-Calgary canal is “the most aggressive and most prolific gene type.”
“So this is not good news for us,” she said, adding a weed notice has been submitted for February with work dredging portions of the canal to continue this spring.
“Results have shown that dredging has been the most effective solution… the question we’re having though is whether we’ll have to dredge every five to 10 years. So constant monitoring is required,” said Tippe.
The risk of not eliminating the plant early is that it could spread into other canal systems that extend north, east and south of the Calgary-Chestermere canal, said Tippe.
She added flowering rush has been found across Canada, but Montana, U.S., is dealing with a particularly complex situation where it has invaded Flathead Lake.
Although it is a long-term project, Tippe said she “feels blessed that it’s (flowering rush) in a canal that can be drained,” which makes the situation a bit easier to handle.
