Water lettuce is often found in slow-moving water and because it’s free-floating, it easily disperses through water currents and often gathers in areas that are more protected. Water lettuce creates thick mats that reduce oxygen levels, block sunlight, and prevent growth of submerged vegetation which have a negative effect on fish and other aquatic species. Water lettuce multiplies through the formation of daughter plants and spreads when horizontal stems are broken from a parent plant. They spread by wind and current but also may be distributed by boats, boat trailers, fishing equipment, and other gear.
The Lake St. Clair Cooperative Invasive Species Management Area (LSC CISMA) removed over 200 water lettuce plants from the Clinton River Watershed in October of 2020. The CISMA prioritized monitoring these areas in 2021 for recurrences and discovered additional plants in October 2021 near a residential area. The LSC CISMA will continue early detection and rapid response efforts to prevent the establishment of this harmful aquatic invasive species. Citizens are encouraged to remove any water lettuce plants from wild waters and place plants securely in the trash. Do not compost invasive plants. Citizens may also report watch list invasive species observances to the Midwest Invasive Species Information Network (www.misin.msu.edu) to notify their local CISMA.
State campaigns, such as RIPPLE or Reduce Invasive Pet and Plant Escapes, help to raise awareness that popular aquatic plants sold, including water lettuce, water hyacinth and European water clover, are not native to Michigan and should never be released into wild waterways. Disposing of unwanted plants in the trash reduces future impacts to MI waters. Water gardens enthusiasts are also encouraged to provide a physical barrier between ponds and wild waters to prevent spread during flood events.
“EGLE and partners such as CISMAs respond to several water lettuce reports each year in public waters around the state. Water lettuce can be legally sold, purchased, and grown in Michigan for use in water gardens or aquaria; however due to the invasive nature and ability to quickly spread response efforts are initiated anytime the plant is reported in public waterways,” said William Keiper, Aquatic Biologist Water Resources Division, Michigan Department of Environment, Great Lakes and Energy.
The Lake St. Clair Cooperative Invasive Species Management Area (LSC CISMA) is a partnership of local and state governments, non-profits, and property owners founded in 2015. United in their goal to prevent, detect, and control priority invasive species, the CISMA operates within the vast boundaries of the Lake St Clair Watershed covering 2,100 square miles. The LSC CISMA is funded by the Michigan Invasive Species Grant Program (www.michigan.gov/invasives).
Six Rivers Land Conservancy is a 501 (c)(3) nonprofit located in Oakland Township whose mission is to conserve, sustain, and connect natural areas, lands, and waters that make the places we live special. We have currently protected over 2,000 acres in Oakland, Macomb, St. Clair, Lapeer, and Genesee Counties. If you'd like more information about our work, volunteer opportunities, or to make a donation, please visit (https://www.sixriversrlc.org).