Lake Guardian

At the beginning of August, the R/V Lake Guardian began its month-long summer survey of water quality and food-web conditions in all five Great Lakes. Data collected will help protect human health and the environment by safeguarding water quality for drinking and recreation, assessing ecosystem stressors, and managing fisheries.

On April 4, 2026, the R/V Lake Guardian began its annual Spring Water Quality Survey. During the month-long survey, scientists will collect water and aquatic life samples from all five Great Lakes to assess the health of the lakes.

During the survey, scientists on the R/V Lake Guardian will collect samples of water and aquatic organisms such as plankton, zooplankton, and benthic invertebrates to assess water quality in the Great Lakes.

Scientist aboard EPA’s largest research vessel, the R/V Lake Guardian, are collecting benthic samples in Lake Michigan to monitor the abundance and spread of invasive quagga mussels.

Scientists recently published a new summary of long-term trends in Mysis populations across the Great Lakes. Mysis diluviana, a small crustacean also known as the opposum shrimp, is an important component of the offshore Great Lakes food web.

EPA Great Lakes National Program Office scientists Megan O’Brien and Matt Pawlowski were interviewed by reporter Susan Bence for WUWM’s podcast “Lake Effect.” In the interview, O’Brien and Pawlowski give Bence a tour of EPA’s Research Vessel Lake Guardian, explain how various sampling equipment is deployed, and discuss the different types of data collected while the GLNPO Summer Water Quality Survey is underway.

The 2023 Summer Survey marks 40 years of long-term water quality and biological monitoring across the Great Lakes.