ИСТИНА

Snail Lake, located in Minnesota, USA, is a small lake (190 acres) with watershed area of 987 acres and maximum depth of about 30 feet. The lake has been known to have a steadily dropping water level, and in 1993 the new augmentation system was introduced, with water from Sucker Lake pumping into the Snail Lake. In 2007 pumping was stopped due to an invasive mussel species threat, and restarted in the end of 2009. In years 2011 and 2013–2016 no water was pumped as water level was maintained by precipitation. One-dimensional General Lake Model was used to simulate Snail Lake’s vertical thermal structure and mixing regime over the period of 2005–2016. With water temperature and specific conductance vertical distribution data from Minnesota Pollution Control Agency and EPA National Aquatic Resources Survey the model was calibrated and validated to create better compliance with real conditions. Information on water pumping rates was provided by City of Shoreview Engineering Department. Patterns in forming of lake stratification were defined for periods with active lake augmentation and periods with no pumping. Differences in lake water temperature and mixing regime associated with different pumping schedules and weather conditions are described. Lake Analyzer tool was used to calculate key mixing indices for different conditions. With lake mixing and stratification being key factors of all temperate water ecosystems functioning, results of this research can be used in connection with biogeochemical studies to gain further knowledge of Snail Lake ecology.