The chief culprit is phosphorus. Although we import this nutrient via such products as lawn fertilizer and petroleum products, phosphorus naturally occurs attached to soil particles which can be carried to the lake by streams and surface runoff. Much of the phosphorus reaching our lakes is a result of erosion and sedimentation. LEA s testing program looks at a number of indicators of water quality related to this nutrient. Temperature readings show if the lake has stratified into an upper warm layer and a deep cold layer.
Stratification is brought on by warm weather.
This is common for lakes or parts of lakes where there is more than 40 feet of water. Lakes of less depth may alternately stratify and mix throughout the summer. Winds and water temperature are the factors which cause mixing and stratification. Lakes mix in the spring when their waters are all the same temperature and winds are strong. By mid to late July, the warm and cold layers are well-defined in deeper lakes.