Generally, Lake Bellaire water quality is very good. The Spring 2004 analysis demonstrated high levels of oxygen down to 28 feet, and low levels of nutrients like phosphorus. However, the Summer 2004 observations showed a dramatic oxygen decline in the deep basin (100 ft.). The low oxygen levels at the bottom exclude fish like lake trout. This low oxygen condition has occurred before and will promote the release of phosphorus from the bottom sediments. This, in turn, will promote algae growth. The causes of the low oxygen levels are not well understood but will be studied when Three Lakes and the Great Lakes Environmental Center build the nutrient-based predictive model for the lake.