Eurasian milfoil in Vancouver Lake is about to meet its chemical match.
AquaTechnex, a Centralia-based company that specializes in invasive species control and toxic algae management, is scheduled to treat the lake this week.
Milfoil is an aquatic invasive species choking the lake in a tangle of vegetation that threatens to make it unusable for rowing, boating and other recreation.
AquaTechnex Manager Terry McNabb said he doesn’t have a precise date for treating the lake; he and Friends of Vancouver Lake are still working out final details. The work, once it begins, is expected to take two to three days, he said.
The Washington State Department of Ecology already has issued a permit to AquaTechnex and authorized using ProcellaCOR, an herbicide the U.S. Environmental Protection Agency approved in February 2018.
McNabb said drones and hydroacoustic mapping were used to identify 614 acres infested with milfoil, which is about 27 percent of the 2,300-acre lake.
AquaTechnex has mapped infestation areas and will use boats with computers, tanks and drop hoses to inject ProcellaCOR below the water.
The herbicide stops photosynthesis in milfoil and causes the plants, which already are 90 percent water, to drop to the bottom where they will quickly decay.
“They break down to pretty much nothing,” McNabb said, adding that he expects the treatment will control 90 to 99 percent of the milfoil in Vancouver Lake.
“If there is treatment next year, it should be substantially less,” McNabb said. “The problem is they can get plants coming in from the Columbia River because they are connected by that (flushing) channel. You probably can never eradicate it.”
Vancouver Lake will remain safe for swimming and other recreation, McNabb said. In lakes where adjacent property owners draw water to irrigate lawns and ornamental plants, they must wait 24 hours after application, he said.
In May, the Port of Vancouver decided to contribute $50,000 to control milfoil in Vancouver Lake. Clark County last month agreed to provide $25,000 this year and another $25,000 in 2020.
Kathy Gillespie, a spokeswoman for Friends of Vancouver Lake, said the group has been successful in raising private dollars.
“We are confident we will be able to pay for this year,” she said. “The question is what happens next year and the year after that.”
Alan Stewart, executive director and head coach for the Vancouver Lake Rowing Club, said the milfoil problem needs immediate attention.
“The lake is in a bad way, and it needs to be looked after,” he said. “I think this is the first step in hopefully getting community backing to do more for the lake.”
Milfoil is a relatively new threat to the lake, which repeatedly has been closed by cyanobacteria, also known as blue-green algae, and elevated levels of E. coli bacteria.