This gross overloading of nutrients into the shallow, warm lake led to problems. These conditions supported huge amounts of plant and planktonic growth. Swan Lake became thick with algae during the summer months. As all this material died and was broken down by bacteria, large amounts of oxygen were consumed, and the lower water levels of the lake became devoid of oxygen, or anoxic. The warm temperatures and lack of oxygen made survival impossible for cold-water fish such as trout. Large fish kills were reported as early as 1952.