CASE STUDIES
Lake Owasso
A lakewide Sonar AS® treatment eliminated invasive Eurasian watermilfoil while preserving the lake’s native aquatic plant community.
THE CHALLENGE
A Lakewide Resurgence Threatens Recreation and Native Habitat
Lake Owasso has long been recognized for its healthy aquatic plant community, but in 2023 the lake experienced a severe resurgence of Eurasian watermilfoil (EWM). Having managed the invasive species since 2000, the Lake Owasso Association observed a dramatic expansion that threatened recreational use, native biodiversity, wildlife habitat, and overall water quality.
To address the infestation, the Lake Owasso Association partnered with SEPRO, Ramsey County, and the Minnesota Department of Natural Resources (DNR) to develop a comprehensive management plan. The goal was to achieve lakewide control while minimizing impacts to desirable native vegetation.
To address the infestation, the Lake Owasso Association partnered with SEPRO, Ramsey County, and the Minnesota Department of Natural Resources (DNR) to develop a comprehensive management plan. The goal was to achieve lakewide control while minimizing impacts to desirable native vegetation.
THE APPROACH
Whole-Lake Treatment with a Low-Dose Systemic Herbicide
After evaluating management options, stakeholders selected a lakewide low-dose Sonar AS® treatment as the most ecologically responsible and cost-effective solution. The treatment was applied in early spring 2024 to allow even distribution throughout the lake.
As a systemic herbicide, Sonar AS® prevents invasive plants from producing the pigments needed to protect themselves from sunlight. Over time, the milfoil depletes its energy reserves and collapses, while slower-growing native plants remain largely unaffected. To ensure responsible management, the program included extensive pre- and post-treatment monitoring using FasTEST® and native plant surveys.
As a systemic herbicide, Sonar AS® prevents invasive plants from producing the pigments needed to protect themselves from sunlight. Over time, the milfoil depletes its energy reserves and collapses, while slower-growing native plants remain largely unaffected. To ensure responsible management, the program included extensive pre- and post-treatment monitoring using FasTEST® and native plant surveys.
Complete Elimination of Eurasian Watermilfoil
The Sonar AS® treatment delivered rapid, sustained control of Eurasian watermilfoil with no observed regrowth during post-treatment monitoring.
0
EWM DETECTED DURING AUG ’24 SURVEY
375
ACRES TREATED
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