Chlorophyll-A
What is it? Chlorophyll A is the photosynthetic pigment that causes the green color in algae and plants. The concentration of chlorophyll in a body of water is directly related to the amount of algae living in the water.
Why is it important? It tells us how much algae are growing in the water. Although algae are a natural part of freshwater ecosystems, too much algae can cause green scums and bad odors, and in more serious cases can decrease the dissolved oxygen levels.
What does it mean? Water with excessive levels of nutrients from fertilizers, septic systems, sewage treatment plants and urban runoff may have high concentrations of chlorophyll a and therefore produce excess amounts of algae.