The quality of water in the Dog River watershed can be gleaned via an examination of the algae it contains. Algae are generally defined as simple, rootless plants that grow in sunlit waters in proportion to the amount of nutrients available to feed on. They are at the bottom of the food chain and, in limited amounts, can be very beneficial as a food source for higher organisms. In large amounts, however, algae can adversely affect the quality of water by inhibiting the photosynthesis process for other plants and by reducing dissolved oxygen levels. Plants and animals rely on many essential nutrients to survive.
Water containing an abundance of dissolved nutrients is capable of supporting a lush crop of algae.
Two nutrients in particular, nitrogen and phosphorus, are essential to algal growth. If these two nutrients are limited in quantity, little algal growth will occur. Widespread algal growth triggered by rich nutrient input can literally turn water green, reducing water clarity. The passage of sunlight through water becomes occluded, harming other oxygen-producing vegetation by reducing the amount of light they receive. As prolific algal growth continues, organisms that feed on algae also multiply.