Starting this month, Lake Ballinger will receive aquatic plant herbicide treatments in an effort to reduce the amount of Eurasian watermilfoil and curly leaf pondweed that has impacted recreational uses.

According to the City of Mountlake Terrace, while targeted herbicide treatment applied in July 2019 and May 2021 have been successful in eliminating much of the Eurasian watermilfoil in Lake Ballinger, some plants remained and are spreading. Troubling amounts of curly leaf pondweed were identified during an aquatic plant survey in summer 2022, the city said. In an effort to avoid a widespread colonization of the lake, additional treatment from May through August this year will target these aggressive aquatic weeds.

Located between Edmonds and Mountlake Terrace, Lake Ballinger is bordered by private homes, a City of Mountlake Terrace-owned park and the Nile Golf and Country Club. The majority of the lake is in located in Mountlake Terrace, so the City of Mountlake Terrace is taking the lead on the project, in partnership with the City of Edmonds.

The work is partially funded through a $15,000 Washington State Department of Ecology grant and the remainder — about $12,000 — being funded jointly by Edmonds and Mountlake Terrace, City of Mountlake Terrace Stormwater Program Manager Laura Reed said.

Lake residents and lake users have reported that the aquatic weeds restrict movement and make it difficult to boat or fish. The decomposing plants smell unpleasant when they die off in the fall, and are capable of triggering increased phosphorus release from lake sediments, which can further stimulate plant growth. These conditions have in the past led to toxic algae blooms on Lake Ballinger. Plants can also cause another kind of hazard: in other lakes, swimmers have become entangled in dense plant stands.

Since the spring of 2018, a steering committee composed of Lake Ballinger lakefront residents, lake users, the Nile Golf Course, an experienced lake specialist and city staff have been meeting to direct invasive aquatic weed control in Lake Ballinger. They have reviewed options, considered impacts, and decided on an adaptive management plan for the lake. This plan, the Lake Ballinger Integrated Aquatic Vegetation Plan, includes use of both physical barriers and selective herbicides to combat larger problem areas around the lake. The plan is available for review on the Mountlake Terrace website.

According to City of Mountlake Terrace, a qualified and experienced aquatic herbicide contractor will treat Eurasian watermilfoil and curly leaf pondweed with the herbicides. Residents and visitors may see a motorized boat on the lake for plant surveys, distributing notification, or applying aquatic herbicide.  The herbicides selected by the steering committee were carefully chosen to minimize risk to humans, fish, and wildlife. No swimming or fishing restrictions are required after application. All lakefront properties will be posted with notification 24 to 48 hours prior to each herbicide application,

The herbicides will be applied carefully to target the invasive weeds and minimize any harm to native aquatic plants, the city said.

The city hopes to start the treatment on May 16 but the work is weather dependent, Reed said.