Bay grasses are plants that grow underwater. Also known as submerged aquatic vegetation or SAV, bay grasses can be found in the shallow waters of the Chesapeake Bay and its streams, creeks and rivers, and are a critical part of the Bay ecosystem. They provide wildlife with food and habitat, add oxygen to the water, absorb nutrient pollution, trap sediment and reduce erosion. Improving water clarity is the most important step in bay grass restoration, because bay grasses need sunlight to grow. Because bay grasses are sensitive to pollution but quick to respond to improved water quality, their abundance is a good indicator of Bay health. You can watch changes in bay grass abundance take place over time using this interactive map.