Lake Ballinger Invasive Aquatic Plant Control

The City of Mountlake Terrace was awarded a 5 year Ecology permit to use herbicides in Lake Ballinger during the summer of 2019 to control Eurasian water milfoil, Fragrant water lily, and Curly leaf pondweed in Lake Ballinger.

Why now? Dense mats of aquatic weeds now cover 80-90% of the nearshore area of Lake Ballinger.  A June 2018 plant survey of the lake showed that nearly 18 acres of Lake Ballinger are covered with a mixture of Eurasian water milfoil (a Class B noxious weed), Fragrant water lily (a Class C noxious weed), and Curly leaf pondweed (a Class C noxious weed.)

Why is it a problem? Lake residents and lake users have reported that the plants restrict movement and make it difficult to boat or fish.  The decomposing plants smell unpleasant when they die off in the fall.  There’s also a safety hazard; in other lakes, swimmers have become entangled in dense plant stands.  

Water quality in the lake has also been impacted by the aggressive aquatic plant growth.  Plant mats prevent wind from mixing surface oxygenated water through the water column.  Low oxygen levels can then trigger increased phosphorus release from lake sediments. These conditions have in the past led to toxic algae blooms on Lake Ballinger.

Whats the goal of the treatment?  The goal of this invasive control effort is to encourage a more balanced native plant community, improve overall lake water quality, and support recreational activities.

What has been done so far?  Since the spring of 2018, a steering committee composed of Lake Ballinger lakefront residents, lake users, the Nile Golf Course, an experienced limnologist, and city staff have been determining the best path forward to address the problem.  They reviewed options, considered impacts, and decided on an adaptive management plan.  The Lake Ballinger Integrated Aquatic Vegetation Plan (available on the Mountlake Terrace website) includes the use of placed burlap bags of sand for localized control on private property, and selective herbicides to combat the larger problem areas around the lake.

Lake Ballinger Integrated Aquatic Vegetation Management Plan

In July 2019, a qualified aquatic herbicide contractor treated approximately 9 acres of Eurasian water milfoil (50% of the shallow lake area) with Florpyrauxifen-benzyl, and in August and September of 2019, treat 25% of the non-native water lilies and pondweed with Fluridone.  The work is being paid for by an Ecology grant. These selective herbicides were chosen by the steering committee in order to minimize risk to humans, wildlife, and to cause the least amount of restriction for swimming and fishing.  Both herbicides have been approved by the EPA and the Washington Department of Ecology.  Prior to herbicide treatment all lakefront property owners will be notified.

UPDATE, June 2020:  The annual aquatic weed survey completed on May 22, 2020 showed that the efforts to control Eurasian watermilfoil last summer were very effective.  Only 2 small patches of Eurasian watermilfoil were found during survey, both on the north end of the lake near the Hall Creek inlet.  For summer 2020, the steering committee for aquatic plant control in Lake Ballinger has decided on a combination of volunteer effort to physically remove fragrant water lilies and a small contract funded by the Ecology grant to have divers install biodegradable bottom barriers at the outlet of Lake Ballinger and other problem areas.  The divers will also be able to hand-pull weeds when they find isolated patches.  No herbicide application is planned for summer 2020 in Lake Ballinger.

Concerns or questions?  Please contact:  Laura Reed, City of Mountlake Terrace, Project Manager at (425) 744-6226.

Remember:  always check boats and fishing gear when you enter or leave the lake; remove all plant fragments and toss them in the trash.

Additional Resources

Eurasian water milfoil

Invasive Eurasian water milfoil

Curly leaf pondweed infestation

Curly Leaf Pondweed Infestation

Invasive lilies and milfoil

Invasive Eurasian water milfoil and fragrant water lilies near dock