Starting Aug. 21, an herbicide will be applied to Eurasian watermilfoil in Vancouver Lake. Applying herbicide in August increases the efficacy of the treatment and helps ensure that conditions are improved and milfoil is significantly reduced before the 2026 recreational season. 

The herbicide being applied, ProcellaCOR, is a selective herbicide that specifically targets milfoil, minimizing harm to desirable vegetation and native plant species. The herbicide was also used to treat milfoil in the lake in 2020. Use of this herbicide does not require a closure of the lake to water contact, though an unrelated “Danger” advisory issued by Public Health is currently in place due to elevated toxin levels from widespread harmful algal blooms in the lake. While the danger advisory is in place, Public Health advises against all recreation in the lake. As required, notices about milfoil treatment are being sent to properties within a quarter mile of the treatment area, 10 days before treatment begins. Treatment will not occur on weekends or holidays. 

An estimated 400 acres of milfoil will be treated in the flushing channel, the rowing lanes on the west side of the lake, and on the south side of Turtle Island. 

Treatment is being collaboratively funded by Clark County, the Port of Vancouver, Friends of Vancouver Lake, and the Vancouver Lake Sailing Club. 

For information about road and park projects, closures, opportunities for community input, and more, residents can follow Public Works on X (formerly known as Twitter), Facebook and Instagram and view information on Nextdoor.