Eradication of Invasive Aquatic Weeds, Can it Happen?

This is often a topic our clients ask us about when they undertake a control program focusing on Eurasian Milfoil or one of the other invasive plant species that plague their lakes. At last week’s Western Aquatic Plant Management Society Meeting ( Kathy Hamel of the Washington Department of Ecology presented an interesting paper on this subject. She highlighted a number of successful eradication efforts that have been conducted in Washington State. Our firm was responsible for the implementation of most of those programs.Sonar Aquatic Herbicide has been one of the key tools we have used in this mission. All of the lakes Kathy reported on had been treated with this technology as the primary step in the eradication process. For example in 1995, we designed a treatment strategy for Goss Lake north of Seattle using Sonar AS. Goss Lake has remained free of Eurasian Milfoil since that date. Another example is Lake McMurray in Skagit County, Washington. Our 2000 Sonar AS treatment has been followed up with yearly diver inspections with no Eurasian Milfoil found for the seventh year now. Kathy also pointed out that continued surveillance and survey is a key step. In lakes where eradication has not been achieved, the populations of plants like Eurasian Milfoil have been maintained in a range where divers can remove the 30-40 plants per year that are found. These lakes remain at “near eradication levels”.

The technology to do this is based on operational research conducted by the US Army Corps of Engineers Aquatic Plant Control Research Program and implemented by our team. The Corps determined if we could maintain low levels of this product around the target vegetation for 6-8 weeks, eradication would be a possibility. We have used a multiple treatment strategy to accomplish this. An initial dose is applied to the lake and SePRO’s FasTEST assays are collected and reviewed at two week intervals. This data is used to maintain that dose. This has resulted in the complete removal of this noxious species and the protection of native aquatic plants in the system.

Thanks for the report Kathy!

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