The shallow water near the shore is a great place for submerged aquatic vegetation (SAV), or underwater grasses, to grow. These grasses give food and shelter to fish, crabs, and other animals. When there are plenty of underwater grasses, it means the water is clean and healthy. 

There are about ten different types of underwater grasses in this area. They can be found from late spring through early fall. The most common ones are wild celery, water stargrass, coontail, and several types of naiads. In the 1970s and 1980s, a non-native grass called hydrilla was brought to the Potomac River. Today, hydrilla is the dominant grass in Mallows Bay. Hydrilla offers some benefits for the environment and is protected in the Chesapeake Bay. However, it can grow very thick and block out sunlight, which can crowd out native grasses.