On Tuesday, May 4, Lake Ballinger will receive another herbicide treatment in an effort to reduce the amount of Eurasian watermilfoil that has impacted recreational uses.

According to the City of Mountlake Terrace, a qualified aquatic herbicide contractor will treat the milfoil on the north, east and southeastern sections of Lake Ballinger with Florpyrauxifen-benzyl (brand name ProcellaCOR). The work is funded by a Department of Ecology grant.

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 lake has in recent years become infested with invasive aquatic weeds, including milfoil, fragrant water lilies, and curly leaf pondweed. The thick aquatic plant beds that cover most of the nearshore area have negatively impacted boating, swimming, and fishing in the lake, officials say. Invasive weeds have also reduced water quality.

Lake Ballinger was treated twice during the summer of 2019 to improve water quality and reduce the risk of swimmers becoming entangled. In 2018, an invasive plant survey of the lake found 16.8 acres of the lake had Eurasian milfoil, while fragrant water lily covered 13.3 acres, and curly leaf pondweed was observed intermittently. After treatment, the fall 2019 invasive plant survey found no Eurasian milfoil or curly leaf pondweed (even in areas that were densely infested in 2018), as well as a significant reduction in the acreage of fragrant water lilies.

Lake residents and lake users have reported that these aquatic plants restrict movement and make it difficult to boat or fish, and the decomposing plants smell unpleasant when they die off in the fall.  Water quality in the lake has also been impacted; low oxygen levels can trigger increased nutrient release from lake sediments. These conditions have historically led to toxic algae blooms on Lake Ballinger.

To address the problem, a citizen steering committee has recommended an integrated aquatic vegetation control plan, including the use of selective aquatic herbicide. The herbicide chosen was selected for the minimal risk to people and animals, and has been approved by the Environmental Protection Agency and the Washington Department of Ecology for use in potable water sources.

No restrictions on swimming and fishing in the lake are required following the May 4 treatment, the city said. Approximately 24 hours prior to herbicide application, all lakefront property within 400 feet of the treatment area (including the Mountlake Terrace boat launch and swimming beach) will be posted with notification and information regarding the treatment.

The city reminds lake users to always check your boats and fishing gear when you enter or leave the lake; remove all plant fragments and place them in your yard waste container.