Storm Water Storm water is runoff water from rain or melting snow that flows across the landscape. Runoff flows off of rooftops, paved areas, bare soil, and lawns. Impervious surfaces are hard surfaces, such as sidewalks, driveways, streets, and rooftops, that don’t allow water to infiltrate into the ground. As the amount of impervious surfaces increases, less water is able to infiltrate into the ground, and more runoff is created.
Storm water runoff is our most common cause of water pollution. Storm water picks up and transports many of the pollutants it encounters, including dirt, pet wastes, pesticides, fertilizers, and automobile fluids. Many of these pollutants can cause problems in very small amounts.