Green Lake spans 2,903 acres with a maximum depth of 110 feet. Known for its clear water and recreational appeal, the lake is suitable for swimming and wading, with good clarity and low algae levels during the open water season. It supports a healthy and diverse aquatic community, though it is currently classified as impaired due to elevated mercury levels in fish tissue, making some fish unsafe for human or wildlife consumption.

Despite this impairment, Green Lake exhibits characteristics of a moderately clear mesotrophic lake and continues to demonstrate strong overall ecological health. Long-term monitoring shows that Total Phosphorus (TP) levels are trending downward and remain well below state thresholds, while Total Suspended Solids (TSS) are slightly increasing—likely due to runoff and erosion—but still within acceptable limits. Chlorophyll-a (Chl-a) levels meet state standards, and Secchi depth readings confirm excellent water clarity and low turbidity.

These trends suggest a resilient ecosystem, but continued attention is essential to prevent future decline. The surrounding landscape—including forests, wetlands, farmland, and developed areas—plays a significant role in influencing water quality through runoff. To maintain and improve current conditions, it's important to continue regular water quality monitoring, implement sustainable land management, and encourage public involvement. With continued stewardship, Green Lake can remain a healthy, valuable resource for future generations.

For more detailed monitoring data, please follow the links below:

MPCA Surface Water Quality Data

MN DNR Lake Finder