2010 Lake Coeur d’Alene Eurasian Milfoil Control Project Success

Aquatechnex biologists implemented a treatment program targeting over 500 acres of Eurasian Milfoil in 2010.

Lake Coeur d’Alene is one of the largest lake systems in Idaho.  It is an extremely important water resource for the region.  While the lake was formed thousands of years ago, the lake was impounded by Avista Corporation with a hydro-electric project approximately 50 years ago.  As part of the FERC licensing process, Avista teamed with the Coeur d’Alene Tribe to implement a number of water quality improvement programs including management of invasive aquatic weed growth.

Eurasian Milfoil has been present in the southern portion of the lake for a number of years.  The Coeur d’Alene Tribe manages this portion of the lake.  The Tribe has had a proactive program to focus on this and other water quality issues for a number of years.  Eurasian Milfoil management had until last year been funded by the State of Idaho Invasive Aquatic Species Grants and the Tribe.  With the Avista License in place, agreements between the Tribe and Avista brought more funding to focus on this problem.
In the spring of 2010, Avista selected Aquatechnex as the most qualified respondent to their Request for Proposal to manage this infestation.  Our team implemented a treatment strategy developed by the Tribe’s Lake Management Team.  We used Dow DMA 4 IVM herbicide to target over 500 acres of dense Eurasian Milfoil.  The Aquatechnex team used precision application vessels with variable length drop hoses to inject this product into the target plant beds.  DGPS tracking systems were used to insure complete coverage of these sites.
As part of this year’s efforts to study water movement in these areas (see blog article on dye study below) our team has had a chance to view a number of the treatment sites from 2010.  Dow DMA 4 is a selective systemic herbicide that targets Eurasian Milfoil and protect native aquatic plants.  Our team performed detailed inspections of these treatment sites one year post treatment.  In all cases, Eurasian Milfoil is gone from these treatment sites.  In addition, there are thriving communities of native aquatic vegetation including a number of species of Potamogetons and Elodea growing where the Eurasian Milfoil was previously.  This technology has restored those areas of the lake to native aquatic plant habitat and have been effective in removing the invasive aquatic species.
The keys to this success were the development of an effective treatment plan, the selection of a product that is selective for Eurasian Milfoil, and precision application technologies including guidance and variable length injection systems.  The Tribe is well in the way to reducing the amount of their waters that are impacted with this noxious aquatic weed.

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