Thole Lake is infested with the aquatic invasive species Potamogeton crispus or curlyleaf pondweed since before 1995 and with Myriophyllum spicatum or Eurasian watermilfoil since 2001.
More information on curlyleaf pondweed
More information on Eurasian watermilfoil
Lake Vegetation Surveys – 2008, 2012, 2013
Lower Minnesota River Watershed Total Maximum Daily Load Report