In a city covered with acres of concrete, asphalt, and buildings, too much rainwater runs directly into the sewer system, washing trash and pollution into our rivers and the Chesapeake Bay. In contrast, gardens and other open spaces soak up rainwater, filtering the water as it soaks into the soil. Planted areas provide many wild animals such as birds and butterflies with food and a place to live—or a resting place during migration. They help to preserve the diversity of animals and plants in Baltimore. Open spaces also help balance the heating effects of buildings and asphalt.