Dave Caswell of the Okanagan Basin Water Board pulls milfoil up by the roots in the colder months. (Richard McGuire file photo)
Flowers, fruit and warm weather aren’t the only things to arrive weeks early this year.
The unusually early seasons have also caused Eurasian milfoil to make an early appearance in the Okanagan lakes.
“It’s looking like a good year for milfoil and that’s bad for the rest of us,” said James Littley, operations and grants manager with the Okanagan Basin Water Board (OBWB), who oversees the milfoil program.
Although Osoyoos Lake shouldn’t experience as bad a problem as some of the other lakes due to an extra effort on this lake during the winter, the milfoil has been reaching the surface much earlier this year.
“I would say it’s four to six weeks early,” said Littley, noting that the milfoil was already cresting the surface in mid-June.
Normally it doesn’t crest the surface until late July or even August, but this year it has crested the surface in a number of locations and is forming mats on top.
Littley expected to have the summer milfoil program underway on Osoyoos Lake by the beginning of July.
Osoyoos Lake tends to be the first to experience milfoil growth, he said.
Last year there were numerous complaints about milfoil growth in part because work was suspended due to concerns by the federal and provincial governments over harm to fish habitat.
During the winter, milfoil is pulled up by the roots, where it floats to the surface and dies. In the summer, this would cause milfoil to spread and reestablish, so the plants are only cut or “mowed” six feet below the surface, but they aren’t uprooted.
Because the fisheries restrictions were resolved last year, rototiller operator Dave Caswell was able to spend more time on Osoyoos Lake this past winter and spring, Littley said.
“Dave spent about a month up there in the winter this time and he went around near the shoreline and around people’s docks,” he said.
One area that is off limits to the milfoil program is the mouth of the Okanagan River as it enters Osoyoos Lake.
The milfoil there is thick enough that actually slows the flow of the Okanagan River. The thick milfoil also has consequences for fish spawning, said Littley, adding that the milfoil bed is so low on oxygen that fish can swim into it and die.
Sometimes bass stay near the edge of the milfoil at the mouth waiting for fry of salmon or trout to come out.
“Then they’ll just kind of pick them off as they go along,” said Littley.
Senior governments are unlikely to relent and allow milfoil harvesting at the river mouth without further scientific study, he said.
“That’s something that I will talk to the board about,” he said. “Whether we need to have a serious look in any of these areas at what the effect is of our control program versus what the effect is of milfoil on the environment.”
Milfoil is an aquatic invasive species that was introduced into the Okanagan Lakes at the beginning of the 1970s. Initially the province partnered with the water board, but in 1998, the province withdrew leaving the OBWB to run the milfoil control program.
This year’s early milfoil season is partly a result of the warmer weather, but it also results from the early spring runoff bringing down silt that settled in the lake before the warm weather arrived.
“It’s really about light penetration and water temperature, so those two things combined are what contribute,” said Littley.
Uncontrolled, milfoil has a negative impact on tourism. Thick milfoil mats can lower lakefront property values by as much as 19 per cent, the OBWB says in a news release.
“Environmentally, milfoil robs oxygen from the water, increases water temperatures, slows the flow at mouths of rivers and increases polluting nutrients in the water,” says the release. “It has been linked to fish kills and loss of biodiversity.”
RICHARD McGUIRE
Osoyoos Times
