A milfoil outbreak in Osoyoos Lake has garnered special attention for crews working on removal of the pesky plant.
The Okanagan Basin Water Board‘s Eurasian Watermilfoil Control program is busy trying to get the jump on the milfoil at the lake‘s north end.
Genevieve Dunbar, office and grants administrator and milfoil control liaison said Wednesday it‘s difficult to determine what caused the milfoil to appear in the lake.
Milfoil is an invasive, non-native aquatic plant that has grown in many Okanagan Valley lakes since the early 1970s. The milfoil control program is the longest-running program operated by the water board, Dunbar said.
“It‘s in all of the main stem lakes in the valley, right from the Vernon arm of Okanagan to Kalamalka, Wood and all the way down to Osoyoos.” she said.
“Anytime plants start growing like crazy, you can‘t determine any one particular factor É that may have caused that.”
Dunbar said there are a couple of possibilities. The first is that Osoyoos Lake is a controlled lake that has experienced low water levels which can increase the water temperature, the concentration of nutrients and a multitude of other factors capable of causing milfoil growth.
Another theory is attributed to the heavy amounts of rain in May and June might have something to do with it.
“There could have been some nutrient runoff, just by general overland flow and runoff into the lake,” said Dunbar, although she noted the milfoil would have had to have responded very quickly for there to be the amounts being reported.
“We were already having people tell us that the milfoil had reached maximum growth, or reaching the surface by end of June, early July,” she said. “It would be quite a magnificent response if that were the case.”
To manage the milfoil the water board has trained an additional operator who has experience working on Christina Lake running a milfoil harvester. Similar to a floating lawn mower, the machine is currently running seven days a week. The machine works by cutting the plant partway through its growth to a length where it is not problematic for boaters and swimmers.
A late winter-early spring program involves use of a bladed machine that de-roots the plant and although more effective than the harvesting machine, Dunbar said it does not eradicate the milfoil.
Boaters can do their part to help control the spread of milfoil by keeping their motors, propellers, water toys, wakeboards and water skis free of any weeds.
“Milfoil spreads by fragmentation,” said Dunbar. “If you move from one lake to another within the span of a day or two, and you‘re taking a whole bunch of milfoil fragments on a prop you can potentially re-colonize new lakes that have not had the problem before.”
Once milfoil has established itself in a lake, the board performs remedial work to help control it to within “acceptable levels.”
Dunbar said the water board‘s control programs have been quite successful in containing the plant and, occasionally the entire basin area gets sporadic, patchy blooms such as the one happening in Osoyoos.
