Jefferson Slough Eurasian Watermilfoil: Whitehall, Montana
Project Contact: Mike Sanctuary, Confluence Consulting, Bozeman, Montana
In 2011, a 20-acre infestation of Eurasian watermilfoil (Myriophyllum spicatum; EWM), was identified within a 4-mile segment of Jefferson Slough near Whitehall, Montana. This aquatic invasive plant is known to impede boat traffic, clog irrigation ditches and pump intakes, displace native aquatic plants, and reduce the abundance and diversity of macroinvertebrates, fish, mammals, and birds within infested areas. Between 2012 and 2015, Jefferson County developed and adopted the Jefferson Slough Eurasian watermilfoil management plan, which outlined three steps aimed at achieving the goals of controlling, and eventually eradicating this infestation. The three steps outlined in the management plan included: 1) disrupting and killing existing infestations of EWM within Jefferson Slough, 2) preventing the recurrence of EWM infestations by modifying Jefferson Slough’s aquatic habitat to a configuration that does not support EWM; and 3) create and maintain hydrologic conditions unlikely to support EWM by improving water and sediment management within and upstream of Jefferson slough.
Between 2015 and 2017, Jefferson County either initiated or completed several phases of the Jefferson Slough Eurasian watermilfoil management plan. In 2016 and 2017, monitoring efforts documented the distribution and abundance of EWM throughout Jefferson Slough. Thus far, results have indicated initial success in eliminating EWM through the relocated channel segment and limited success in the effectiveness of herbicide treatments in reducing the abundance of EWM within the infested reach.
To learn more about this effort, view the full restoration highlight here: Restoration Highlight pdf