A cold winter leading into a wet spring has presented a scheduling setback for the summer milfoil harvesting season.
The late freeze this year affected the milfoil purge start on Osoyoos Lake and Wood Lake, but it did allow more initial extensive rototilling of the lake weed on Okanagan Lake around Kelowna and West Kelowna beaches.
Winter derooting is considered the most effective control method because the weeds are dormant and won’t re-root.
“We just confirmed a machine being launched in the north end of Okanagan Lake this week which is a little bit behind schedule from where we are normally at this time of year,” said James Littley, operations and grants manager for the Okanagan Basin Water Board.
“Areas that we would normally get to in the beginning of July are getting treatment now in the beginning of August because the high water mark made some of those areas inaccessible for launching our machines.”
The rising lake levels brought along the problem of debris, both posing a risk to milfoil control machines by cutting the harvesting teeth and submerging weeds that become suddenly very visible as the water level drops forming dense weed mats on the surface of the water.
Boaters are asked to avoid such mats as breaking off plant fragments can spread the weeds to new locations and create a mess along the shoreline.
The water board employs four full-time milfoil harvesting machine operators with a fleet of three rototillers and one shallow-water derooter; and two summer harvesting machines.
Littley said the rototillers are the most effective weapon to control the milfoil because they uproot the plant, whereas the harvesters only cut them back.
Despite the delay, Littley said complaints about weed growth in the area lakes are on a par with past years.
“We are seeing similar volume of calls but people are not as impatient and a little more understanding of the conditions we’ve been dealing with out there given what happened in the spring,” he said.
He said the priority is to clear the public beach swimming areas first and then deal with private complaints.
“Sometimes we don’t have permits to go into certain areas and can’t respond to complaints, and sometimes there is a misunderstanding about what kind of weeds may be growing,” Littley said.
“We only have a permit to harvest milfoil but there are about 10 different weeds that are native to Okanagan Lake.”
Why and where the milfoil grows in a given year is the result of many conditions such as volume of spring runoff, clarity of the lake water, nutrients in the water and where structures such as boat docks disrupt the normal water flow.
He said chemical treatments are done in the U.S. but such programs are no more effective than machine harvesting, Littley noted.
“The trade-off is we are not putting chemicals into the water but still have an effective form of treatment,” he said. “Milfoil isn’t going anywhere. It is here to stay as a long-term problem.”
Little said the public can also access the harvested milfoil as it is useful as a composting agent in gardens and orchards because of the inherent nutrient value.
“It’s similar to a mild commercial grade fertilizer when it breaks down,” he said.
The OBWB will organize for dump truck loads to be dropped at a yard or orchard if near a harvesting site, or tell people where they can pick up milfoil piled up on a beach for disposal. Call 250-469-6270.
