A bloom is a visible manifestation of algae. Usually the algae are one celled, green plant-like organisms. Blooms usually occur during hot weather when the upper layers of water warm up due to the calmness of the lake. The warm temperature, along with high levels of nutrients in the water, causes the metabolism of these tiny plants to increase tremendously. This involves super levels of reproduction until trillions of these little algae are produced. Often algae blooms are accompanied by tiny animal blooms upwards along the food chain. With the advent of zebra mussels, blooms are less frequent in the Finger Lakes.
Microscopic algae similar to these live in the ocean along the edges of land masses and are responsible for about 80% of the food and oxygen production on the earth.
Frequent or continuous blooms in fresh water indicate poor quality water. Swimming should be minimized during an algae bloom, as some types of blooms have been known to cause dermatitis and other disorders. Even though our lakes experience some awesome looking algae blooms, the water quality here is still rated as excellent.
However, heat and nutrients, such as phosphates, accelerate the rate of eutrophication of a lake. The Lake Source Cooling project proposed by Cornell will redistribute phosphorus to an area of the lake where the nutrients can support plant life, effectively increasing the phosphate content, but not actually adding additional phosphates. The project will also directly add heat to the lake.