Nowadays, Ilgamho Lake has become green because of algal blooms. Among all the algae, the biggest cause of the color is cyanobacteria, or blue-green algae. Cyanobacteria absorbs the nutriments which have indium and nitrogen.
They grow quickly, so a "bloom" happens. There are plenty of nutriments in Ilgamho Lake. Most of them come from the deep mud layer of the lake's sediment. Mainly, nutriments flow out of the mud layer and they stimulate the growth of algae. Moreover, since the lake is confined, no water pours in and the water becomes dirty naturally.
These are conditions in which algae can grow well. Also, the temperature affects the growth. Because Ilgamho Lake has many nutriments, algal blooms always occur regardless of the season on it. However, the most of the harmful algae occurs when the temperature becomes high, so summer is when the peak growth occurs. To make matters worse, cyanobacteria secrete a substance that
makes the lake stink and toxin. For these reasons, Ilgamho Lake looks green and students can smell a nasty odor during summer. Thus, Konkuk University (KU) has taken a step to deal with algal blooms. The main way is using a boat on the lake. If the algae bloomed, they would rise to the surface of the lake. Consequently, using a boat can break the bloom on a surface and mix the water. It is a temporary measure because it cannot get rid of algae entirely. Still, though it is a temporary expedient, it can dilute a degree of the algae.