EPA’s Largest Research Vessel Launches Great Lakes Water Quality Survey
The Lake Guardian sets out to assess the health of all five Great Lakes, collecting data on plankton, nutrients, and water quality to guide environmental protection efforts.
- By Stasia DeMarco
- August 01, 2025
The EPA's largest research vessel, the Lake Guardian, will begin its annual summer water quality survey through each of the five Great Lakes.
During the month-long survey, scientists will collect samples of water and small aquatic organisms like plankton, critical species in the lower food web. Data gathered on the annual surveys enables EPA and partner agencies to assess how invasive species and algal blooms affect fisheries and water quality to better protect the Great Lakes for drinking water, fishing and recreation.
The survey will sample the lakes when warmer surface water overlays colder bottom water—conditions which influence nutrient and oxygen levels, algal growth, organism distributions and fish habitat. Scientists will also collect a variety of water quality measurements to verify and improve algorithms used for the satellite-based measurements which complement EPA’s ship-based monitoring surveys.
Scientists from the Oak Ridge Institute for Science and Education, University of Minnesota Duluth, Cornell University, Michigan Technological University’s Research Institute and Great Lakes Research Center, and SUNY Buffalo State University will join EPA scientists to conduct the survey.
Since 1983, EPA has conducted sampling surveys in the spring and summer to provide a comprehensive assessment of the lakes’ health, part of the longest-running and most extensive monitoring dataset for all five Great Lakes. The R/V Lake Guardian is funded by the Great Lakes Restoration Initiative, launched in 2010 to protect and restore the world’s largest surface freshwater ecosystem.
Read more about EPA’s Great Lakes monitoring programs.
About the Author
Stasia DeMarco is the Content Editor for EPOnline.