Rochester’s water cycle is no longer natural; it has become "urbanized" by the creation of human habitat with lots of hard, impervious surfaces like streets, roof tops, or even construction sites. These impervious surfaces prevent water from soaking into the ground, so when it rains or snow melts, this run-off (or stormwater) runs across both natural and constructed surfaces. As a result, this change to urban areas causes less recharge and creates more runoff that moves across the landscape faster. More and faster moving water can cause erosion and can collect pollutants as it moves and transports them to receiving waters.
Today, storm water pollution is regulated at the federal, state and local levels. The regulations derive from the Federal Clean Water Act (CWA) that was passed by Congress in 1972. The City of Rochester is required by law to manage stormwater that runs off the land within the city limits.