The present state of Lake Balang Tonjong Makassar has experienced eutrophication, evident from the murky and foul-smelling water, the abundance of wild plants like lotus and water hyacinth, and the shallowing in various parts of the lake, which has led to flooding in Makassar. Eutrophication occurs due to uncontrolled growth of phytoplankton from the groups Chlorophyta, Basillariophyta, Cyanophyta, and Dinoflagellata. This study aimed to determine the value of physical and chemical environmental parameters in the eutrophication process, find the triggers for eutrophication and determine the level of eutrophication at each station. The research method was carried out using a quantitative descriptive approach, with a purposive sampling technique applied at five station points which were considered to represent the research area. The results of the study on eutrophication in Lake Balang Tonjong Makassar obtained the following: 1) Environmental parameters that affect the eutrophication process show extreme conditions, which in general have exceeded the environmental quality standards set by the government of the Republic of Indonesia. 2) Trophic status at each station is at the eutrophic level (station I, station II and station III; while station IV and station V are at the hypertrophic level; 3) The trigger of eutrophication is very extreme, namely at stations IV and V, around traditional markets and household waste channels.