Lake aging process Trophic state is another indicator of water quality. Lakes can be divided into three categories based on trophic state-oligotrophic, mesotrophic, and eutrophic. These categories reflect a lake' s nutrient and clarity levels.
Oligotrophic lakes are generally clear, deep and free of weeds or large algae blooms.
Though beautiful, they are low in nutrients and do not support large fish populations. However, oligotrophic lakes often develop a food chain capable of sustaining a very desirable fishery of large game fish. They are usually either weedy or subject to frequent algae blooms, or both. Eutrophic lakes often support large fish populations, but are also susceptible to oxygen depletion. Small, shallow, eutrophic lakes are especially vulnerable to winterkill which can reduce the number and variety of fish.